Technical Information For The Collision Industry

January-February 2001

Inside AdvantageInside Advantage

Collision

Refinishing

Mechanical

Multiple-Stage Airbags 4

Though these airbags look

deployed, there may still be a

live igniter on-board. The

main concern is proper

disposal.

Spray Gun Fluid Tip,Needle, And Air CapSelection 6

A discussion on why the

correct matchups are

important.

New Approaches ToCollision Avoidance 10

Concept systems are aimed

at preventing a rear collision

and protecting people

outside the vehicle. One

strategy includes the addition

of external airbags.

Also Inside–

Honda Insight Collision Repair Issues–A Required Attention To Detail

The unibody frame, as well as the roof, quarter panels, and doors on the Insight are made of aluminum alloys.(Courtesy of The Aluminum Association)

Continued–Page 2

– Head curtain airbags nowoptional on Saturns

– Airbag recommendationschart updated

– New California law focuseson collision repair

– Concerns with coolantformulas and boiling points

The Honda Insight, which was introduced inthe 2000 model year, is interesting to theCollision Repair Industry for two mainreasons. First, it’s a gasoline-electric hybrid.Hybrids are proving to be a popular form ofpropulsion for vehicle makers trying to meetnew Corporate Average Fuel Economy(CAFE) requirements, and consumers tryingto offset the rising price of gasoline. Sorepair facilities should be seeing a lot ofthese types of vehicles in the years ahead.

Secondly, it’s an aluminum-intensive vehicle.The Insight has an aluminum frame,suspension, roof, quarter panels, and doors(see above Figure). Other body panels, suchas the front fenders and rear fender skirts,are molded plastics. More vehicle makersare building vehicles with aluminum in anattempt to save weight and meet the sameCAFE requirement. Repair facilities havebeen forewarned of an aluminum vehiclebarrage, but relatively few facilities are

prepared with either the special equipmentor training required.

This article will look at the issues that collisionrepair facilities need to know before encoun-tering a collision-damaged Insight.

HYBRID POWER SYSTEM

The powertrain on the Insight consists of a1.0 liter, 3-cylinder gasoline engine, a 10-kilowatt electric motor/generator, and anickel-metal hydride battery pack. Hondarefers to the hybrid power system asIntegrated Motor Assist (IMA™). Like allhybrids, the vehicle never has to be pluggedin to re-energize the batteries. Regenerativebraking recharges the batteries wheneverthe vehicle is decelerating.

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Honda Insight Collision Repair Issues–Continued From Page 1

Service Cautions

Also like other vehicles where at leasthalf of the power is electric, repairfacilities must be aware of safetyprecautions with high-voltage circuitsand battery electrolyte. Some of thecircuits on the Insight carry 144 volts.These circuit cables and their covers areidentified with a bright orange color.There are also caution labels attached tothese parts. The Insight Body RepairManual warns to wear insulated gloveswhenever inspecting or servicing theIMA™ system. The battery also must beswitched OFF. The switch is under asmall cover plate under the trunk floormat (see Figure 1). Just because theswitch is OFF does not mean there’s nohigh voltage. There still may be highvoltage if the engine is running.

The battery electrolyte is potassiumhydroxide, a highly caustic (alkaline)material that can burn skin. The batterypack is protected in the rear of thevehicle, and not likely to be damaged ina collision. Technicians are given aphone number to call the Honda hotline if there is damage to the enclosure,and a list of materials to have on hand atthe scene of a collision in case of anelectrolyte spill. These materials include:

� insulated or rubber gloves, protec-tive goggles, and safety shoes.

� red litmus paper, which turns blueto show a highly caustic spill.

� 20 liters of saturated boric acidsolution, to neutralize the alkali.

� an ABC fire extinguisher, since asmall amount of water would onlyspread an electrical fire.

Figure 1–The battery is turned OFF with a toggleswitch in a compartment under the trunk floormat. A locking cover assures the switch remainsin the OFF position during servicing.

LockingCover

Battery Module Switch

� shop towels, for wiping upspilled electrolyte.

� cloth adhesive tape, for insulat-ing bare wires.

� a voltmeter, to test for high-voltage in the circuitry.

BODY STRUCTURE ISSUES

The aluminum body design is based onthe experience Honda/Acura devel-oped with the NSX, the world’s firstaluminum-bodied vehicle. The chassisuses a combination of extruded,stamped, and die-cast aluminum. Bodyweight is about 40% less than acomparable size steel body.

Front Side Frame Extension

One notable available replacement partis the front part of the lower front rail,called the front side frame extension.This extension has a built-in crush zone,designed to collapse in a front collision.It is easily replaced with six bolts (seeFigure 2). This replacement procedure isfamiliar to anyone who has worked onan Audi A8, another aluminum-intensivevehicle. The A8 has a similar front railextension replacement part that boltson, but the part was originally all welded.The frame rail extension for the Insight isboth welded and bolted on. It’s boltedon the frame rail, in the same location asthe replacement extension is bolted on,and welded to the radiator core support(see Figure 3).

Upper Core Support

Front SideFrame

Front Wheelhouse

Front Side Frame Extension

8 x 1.25 mm

Figure 2–The lower front rail is designed tocrush, but is easily replaced with bolts.

Sectioning Not Recommended

There are at least two specific state-ments in the Insight Body RepairManual that inform technicians not tosection a part, but to “make repairs atthe factory seams.” One example is inreference to the B-pillar. Another is inreference to the front upper rail. This isa general recommendation for allstructural parts on the Insight.

The lack of sectioning recommendationsdoes not appear to be a major issuewith this vehicle. Besides the lower frontrail extension, there is no “uniside” oreven a door ring without a factory seam.The floor pan is conveniently available inthree parts: front, middle, and rear. Theillustration in Figure 4 shows that there’seven a further breakdown of partsusually considered part of the floor pan.

WELDING GUIDELINES

Honda is specific regarding weldingprocedures and cautions when welding,even specifying exactly how muchaluminum oxide to remove so the weldis not contaminated.

Use GMA (MIG)

GMA (MIG) is the welding process ofchoice for the Insight. This processrequires getting into position andfinishing the weld quicker than with

Bolted-OnExtension

Welded To Core Support

Figure 3–This mass production body weldingdiagram shows that the front side frameextension is both originally bolted and welded.The original bolts are in the same locations asthe replacement bolts.

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other processes. Honda is concernedthat other welding processes, such asgas tungsten arc (GTA or TIG), havetoo large a heat-effect zone whichcan have a detrimental effect on themicrostructure of the aluminumalloys. This is because current isalways being varied when GTA (TIG)welding by either a foot or hand-operated control, and the current caneasily be set too low. This requiresextended time to start the weldingpuddle and progress the weld. Itdoesn’t look like the metal is beingaffected, because aluminum does notchange color, but too much heat isbeing conducted into the base metal.With the GMA (MIG) process, thecurrent is set on the machine at alevel to make a good weld. It’s easy torecognize that a proper weld is notbeing made if the current setting istoo low.

Oxide Removal

When plug welding, the body repairmanual specifies to sand off a 25 mm(1") diameter area of aluminum oxidefilm around the plug weld hole on theface side. On the underside of the topbase metal and the top side of thebottom base metal, a 15 mm (0.6")diameter area of aluminum oxide filmshould be removed. When plug weldingthree or more pieces, a 25 mm (1") circle

nuary-February 2001

Figure 4–The Insight floor pan is available in three pdashboard break down the usual floor pan assembl

Front Floor Pan

of aluminum oxide film should also beremoved under the bottom-most basemetal. The manual is just as specific withthe fillet weld and butt joint. For the buttjoint, aluminum oxide is to be removedto a width of 20 mm (0.8") on the jointline on the face side, and 10 mm (0.4")on the underside.

Welding Cracks

The welding of fine, minute cracks isallowed. This does not include cracksthat form during straightening. If thatoccurs, the part must be replaced. Butafter the repair is made, if there arehairline cracks revealed with dyepenetrant, these can be repaired bywelding. The procedure is to drill holesat both ends of the crack to prevent itfrom spreading, and weld the crackstarting at each end, leaving the crater inthe middle (see Figure 5). If a crack isdetected in a weld, this can also berepaired by grinding off an area twice aslong as the crack and rewelding.

HEAT FOR STRAIGHTENING

When straightening steel frame parts, theuse of a torch to soften the steel isavoided whenever possible. With thenon-tempered aluminum alloys used forthe sheet metal, the use of heat isencouraged. The Insight Body Repair

ieces. The separate crossmembers and lowery even further.

Rear Floor Pan

MiddleFloor Pan

Manual says that at temperatures above200° C (392° F), elongation characteris-tics of the aluminum alloy are improved,making it easier to work. But the metaltemperature shouldn’t get too hot either.

The use of temperature indicators, suchas thermal paint, are required to monitorthe applied heat. The manual says tochoose a paint that changes color atabout 110° C (230° F) and apply a stripabout 25 mm (1") from the outercircumference that will be exposed tothe torch flame. If the heating is stoppedwhen the thermal paint color clearlychanges, the temperature of the heatedarea will be less than 400° C (752° F),well below the melting temperature ofaluminum, 640° C (1,184° F). Hondacautions to not attempt to straighten theextruded aluminum parts of the unibody.

CONCLUSION

The hybrid Honda Insight poses severalchallenges to collision repair facilities,specifically due to the electrical parts on-board and the aluminum makeup. Thebody repair manual, available fromHonda, includes specific recommenda-tions to help guide the repair in each ofthese areas to help assure that properlytrained technicians can rise to meetthese challenges.

Just like any new technology, onceunderstood, hybrid aluminum vehiclescan be repaired efficiently and safely.Both body and service technicians havelearned to respect and deal with other“high power” systems found in today’svehicles with minimum risk.

All illustrations courtesy of American Honda MotorCompany, Inc.

Figure 5–Welding a hairline crack.

Crater Treatment

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4

Collision

First Stage Airbag Deployment

First And Second Stage Airbag Deployment

Figure 3–Graphic illustration of the differencebetween a single-stage and dual-stagedeployment. The second stage provides a longercushion. (Courtesy of Ford Motor Company)

Multiple-Stage Airbags–Second Stage May Not Be Deployed

Multiple- or dual-stage airbags addanother potential risk when working ona vehicle after an airbag deployment: anundeployed inflator still on-board eventhough the airbag has deployed. It usedto be obvious at first glance that theigniters for both the driver and passengerairbags had activated. The deployedairbags were visibly hanging from thesteering wheel and instrument panel. Butmultiple-stage means that there are twoigniters for each airbag module, and onmost vehicles so equipped, it is possiblethat either the passenger and/or driverairbags can be deployed only at the firststage with the second stage still intact.This means that disposal and handlingmethods must be similar to that of a liveairbag even though the airbag is visuallydeployed. There’s no visual evidence,whether the airbag module is in thevehicle or removed, if both or only oneof the stages has been activated.

Figure 2–A hybrid inflator uses compressed argongas as the propellant. A passenger inflator isshown, but is also used for some driver airbags.

Figure 1–A conventional, single-stage, airbag hasa connector which fires the igniter, which lightsthe contained sodium azide pellets.

OPERATION

Single-stage, or conventional, airbagswork when the control module signalcauses the igniter to fire, causing thepropellant to burn, releasing nitrogengas to inflate the airbag (see Figure 1).An inflator system that’s becomingcommon for both driver and passengerairbags is shown in Figure 2. This systemuses pressurized argon gas as a propel-lant. With this type of system, the ignitersets off a chemical reaction, whichreleases and heats the gas, causing it toexpand and inflate the airbag.

Multiple-stage airbags are designed todeploy at different rates depending onthe severity of the collision (seeFigure 3). There are other factors thatadd into the equation depending on thesystem, such as if the seat belts arebuckled or the position of the occupant,but the severity of the collision issomething all multiple-stage systemshave in common. If the collision issevere, both igniters deploy almostimmediately to get the airbag in theproper position. If the collision is lesssevere, there is either a delay betweenthe firing of the igniters or only one ofthe igniters fires, depending on thesystem. For systems with a delay, thedelay is only a few milliseconds, but it’senough to shorten the rate of theinflation and lessen the force of theinflating airbag. The second stage is alower force than the first stage, such as a70/30 or 60/40 ratio. This may be donewith two separate chambers inside theairbag module, each equipped with anigniter and propellant.

That’s the way multiple-stage systemsare supposed to work. But somethingcan go wrong, such as an electronicglitch or a cut wire.

CONCERNS

The concern with the inactivated igniteris both a minor safety risk and a majordisposal issue.

Safety Risk

The second stage in these airbags is notas strong as the first stage. The first stageis designed to burst the fabric from thecontainer and inflate the airbag to itsproper size. The second stage is just asupplement, designed to maintain theinflation for a few milliseconds longer.When the airbag is visibly hanging fromits mounting and the second stageaccidentally goes off, there’s not muchinflation at all. With an argon gas inflator,the gas has already been dispersed. Thesecond stage would simply be a small“pop” as the igniter activates.

The second stage is still a pyrotechnicdevice, and therefore all precautionsshould still be taken as if it were a fullyundeployed airbag. Each vehicle makerhas its own deactivation procedure. Itusually requires disconnecting andisolating at least the negative batterycable and waiting up to two minutes toallow the reserve (capacitor) charge todissipate. Some systems require removalof an airbag fuse and disconnecting theairbag module electrical connectors.Follow the vehicle-specific procedure.

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Disposal Issue

Repair technicians and recyclers havecome to believe that a deployed airbagcan be disposed of as normal waste. Anunfired igniter puts the airbag in thecategory of hazardous waste, subject tostiff fines. It is recommended to treat allmultiple-stage airbags as live airbagmodules, whether deployed or not, andfind the proper procedures for testingthe module, manually deploying theunfired igniter, and disposal.

Recyclers must not dispose of anymultiple-stage airbag until manualdeployment procedures are attemptedfor both stages.

TESTING AND MANUALDEPLOYMENT

With many multiple-stage airbagsystems, it is possible to test whetherthere is an undeployed igniter. Theprocedure generally requires a vehiclemaker-specific scan tool. One example

� Buick LeSabre� Chevrolet Impala, Monte Carlo� Chrysler Sebring, Town & Country� Dodge Caravan, Stratus � Ford Crown Victoria, Windstar� Jaguar XK8� Lexus LS430 (passenger only)� Lincoln Continental� Mercedes-Benz (all)� Mercury Grand Marquis� Nissan Maxima� Oldsmobile Aurora� Plymouth Voyager� Pontiac Bonneville� Volvo S60

1999

2000

2001

� Acura RL

� Acura 3.5RL, 3.2RL� BMW 3-, 5-, 7-series� Ford Taurus� Honda Accord V6, 4-cyl EX-L� Mercedes-Benz S-Class� Mercury Sable

Figure 4–A partial list of vehicles with multiple-stage airbags, and the model year the systemwas introduced.

nuary-February 2001

of a procedure is for a 2000 Ford Taurus/Mercury Sable:

1. Deactivate the system.2. Attach the scan tool to the data link

connector.3. Perform the on-demand self test.4. Determine if codes B2234 or

B2235 are in the memory duringthe on-demand self test.

5. If B2234 or B2235 are set, thedriver or passenger airbag secondstage has deployed and the airbagmay be disposed of the same asother parts to be scrapped. If thesecodes are not found, the secondstage has NOT deployed andappropriate airbag disposal proce-dures must be followed to safelydeploy the second stage. Toremotely deploy the airbag, consultthe service manual procedures andfollow them step by step. Oncedeployed, and allowed to cool, theairbags can be disposed of thesame as other parts to be scrapped.

At least one vehicle maker, GeneralMotors, does not have a procedure fortesting to determine the state of thesecond stage of a multiple-stage airbagafter a deployment. General Motorsrecommends following the manualdeployment procedure before disposingthe airbag module. This system isdesigned to only deploy the first stage ina moderate frontal collision. And not allvehicle makers list a manual deploymentprocedure. DaimlerChrysler deferstechnicians to hazardous substancecontrol procedures at the local, state,provincial, and federal levels for bothmanual deployment and disposal. Anofficial DaimlerChrysler procedure is stillbeing developed.

IDENTIFICATION

One way to tell, at least up to the 2001model year, if an airbag is multiple-stageis to look at the back of the module.There are two connectors. But that willchange on some vehicles as early as the2002 model year. A technology called“AC firing” allows two igniters to be firedfrom a single connector.

For the easiest identification, it’s best tohave a list of which vehicles areequipped with multiple-stage airbags(see Figure 4).

SIDE IMPACT CURTAINAIRBAGS AVAILABLE ON2001 SATURNS

Head curtain airbags are now availableas an option on the Saturn 2001 L-Seriessedan and wagon and S-Series sedan,wagon, and coupe. The curtain is storedalong the upper roof rail behind theheadliner and trim pieces. The airbagdeploys by dropping from the roof rail,unfolding as it inflates, providing acushion to help protect the head andneck in a side collision (see Figurebelow). Saturn subjected vehicles to avariety of tests, including a 29 km/h(18 mph) side-impact test where a poleis aimed at a test dummy’s head. Thesetests showed that the addition of a headcurtain airbag creates the potential tosignificantly reduce head injury.

MORE AIRBAG PARTSREPLACEMENTINFORMATION AVAILABLE

A reminder that the Airbag PartsReplacement Recommendations chart isavailable on-line, at the I-CAR web site.The listings now include the completecharts for model years 1993–1999 andmost 2000 model vehicles.

You can access the chart information,free of charge, by going to the web siteat: www.i-car.com. Select “I-CAR” fromthe blue bar at the top of the page,then “Advantage” from the choices. Atthe Advantage page, click on the “e” onthe Advantage title. This will bring up thecover page of the Airbag Parts Replace-ment Recommendations charts.

The optional head curtain airbag drops from theheadliner. (Courtesy of Saturn Corporation)

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Refinishing

Spray Gun Fluid Tip, Needle,And Air Cap Selection–Matching To New Finish Materials

Spray gun fluid tip, needle, and aircap selection is an important processtoday due to the increasing variety ofpaint materials. No longer can a spraygun be set up based on the materialjust being either acrylic enamel,acrylic urethane, or polyurethane. Arefinishing technician used to havespecific setups for primer surfacer,lacquer, acrylic, and maybe one forclearcoat. These setups could be usedwith almost any paint maker’smaterial. No longer is that the case.One size does not fit all.

Refinishing today requires applicationwith specific air cap, needle, and fluidtip combinations. These new specifi-cations are based on the fluid viscos-ity (thickness), ability to atomize,flow-out, flash time, and dry time.

Most refinish material makers have achart with the recommended fluidtip, needle, and air cap sizes fordifferent types of spray guns. Thisarticle will discuss why thesematchups are important.

ATOMIZING THE MATERIAL

All refinish materials must be atomized,or broken into fine particles and mixed

Figure 1–The area where the fluid and air meetis very small.

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��yyAir

Air

Fluid

with air. These particles are then carriedto the vehicle by the same air thatcreated the breakdown. The importantfactors are where and how this atomiza-tion takes place.

As the refinish material leaves the fluidtip, either by siphon or gravity, the fluidis first mixed with air exiting around thefluid tip. Then it’s bombarded by air fromthe air cap horns. As shown in Figure 1,this meeting of air/fluid takes place in avery short distance. This is where theentire design of the pattern takes place.The volume of air, and the speed andvolume of fluid, determine the air-to-fluidratio or atomization. There are othercontributing factors that can’t beignored. The main ones are:

� air pressure at the air cap.� air volume.� viscosity of the material.

Pressure

With the HVLP spray gun, air pressure atthe air cap is a more important factor.Minor adjustments greatly affect theapplication and can be the contributingelement to a satisfactory finish. A rangeof 10–15 psi is the starting point, butthen fine-tuning takes over. Test patternswill show when proper adjustments aremet. Low pressure doesn’t allow properpattern size, breakdown of the fluid, orproper evaporation of the active solventsthat are designed to be lost in flight. Poor

Figure 2–Note the large size of the center orificein these HVLP spray guns.

hiding and excess texture result from thiscondition. Excess air pressure causesextra evaporation of the active solvents,increases overspray, and generally resultsin a dry or dull finish.

Air Volume

Air volume, or CFM, has a major impacton atomization. HVLP spray gunsdepend on the mass of air to breakdown high-solids materials. Compare thephoto of HVLP spray guns in Figure 2 toa conventional spray gun and notice theextremely large center orifice opening inthe HVLP spray gun. These extra largepassages carry extra air volume for aquicker start of evaporation. Air starva-tion is one of the biggest contributors topoor spray gun performance.

Air hoses used for spraying should besized to deliver ample air volume. Whenusing an HVLP spray gun, air hoses thathave a 10 mm (3/8") inside diameterhose, larger inside diameter quick-couplefittings, and a length that does notexceed 9 meters (30 feet) should beused. This combination allows foradequate air flow.

Viscosity

The thickness or thinness of the spraymaterial is also a main determinant forwhich setup to use.

MAKING THE RIGHT CHOICE

Reaching the goal of achieving properatomization for ideal breakdownrequires some research and review ofvarious equipment and setups.

Figure 3–Two types of air caps showing differenthorn hole configurations.

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New California Law AddressesFraud Issues–A Model For Similar Legislation?

Thick undercoats no longer need aspray gun with giant fluid tips to “pourit on.” In fact, the reverse is happening.Better atomization occurs with thistype of material when a smaller fluid tipand needle and an air cap with largerair passages is used. The lower airpressure results in less overspray, asmoother finish, easier sanding, andless material used. Thin basecoats canbe applied with medium-size fluid tipsand needles and moderate air flowachieving the same goal of goodcoverage, smooth surface, fast recoator clearcoat time, minimum overspray,and less material use.

Air pressures have lowered to what isconsidered unbelievable levels. Pres-sures vary from lows of 10 psi up to 50psi, all being measured at the spray guninlet. Again, air hose size becomesmore important in providing the propervolume and not just pressure.

Thus the research will require listing thebrands and materials used. Identify andlist information such as viscosity,reduction rate, spray pressure, andrecommended fluid tip, needle, and aircap size. Review technical sheets onvarious spray guns searching for amatch to the material requirements. Donot select a spray gun based on brandname alone.

Fluid tip diameters have becomesmaller and now range from 0.91 mm(.036") to 2.5 mm (.090"). Air caps asseen in Figure 3 will be as simple asone horn hole on each side, to twohorn holes and multiple secondarycenter orifices. Some spray gun makersrequire the specific pairing of a fluid tip,needle, and air cap, while others allowmultiple air caps to be used with a fluidtip and needle combination.

CONCLUSION

New types of refinish materials empha-size higher solids/lower solvents, quickdry features, finer pigments, glamourparticles, and more viscous resins. Thesechanges require continued training andresearch into spray equipment, such asthe proper fluid tips, needles, and aircaps that will provide a customer with asatisfactory finish.

anuary-February 2001

A new law in California, Senate Bill1988 (SB 1988), that took effectJanuary 1, 2001 addresses a varietyof Collision Repair Industry issues.Provisions affecting the CollisionRepair Industry were added ormodified as a result of hearingsconducted in the Fall of 1999 by theSenate Insurance Committee. Thehearings focused on collision repairfraud, vehicle insurance fraud, andvehicle thefts.

SB 1988, among other things,provides the following:

� Requires the Bureau of Automo-tive Repair to implement a pilotprogram to inspect insuredvehicles to ensure the repairsmatch the final invoice. The billallocates a fund to the Bureauto complete the study by June30, 2003.

� Makes it illegal for an insurer torequire a shop to pay the costof an insured’s rental vehicle ortowing charges as condition ofparticipation in a direct repairprogram. However, the insurerand the collision repair facilitymay agree in writing to termsand conditions under which therental vehicle charges becomethe responsibility of the repairfacility when the repairs are notcompleted within the agreed-upon time.

� Allows a registered collisionrepair facility that is deniedparticipation in an insurer’sdirect repair program to report adenial to the insurance depart-ment, which shall maintain arecord of all those denials for

the purposes of gatheringmarket conduct information. Aninsurer, upon the request of thedepartment, shall disclose thefact that a denial was made.

� Requires insurers that conduct alabor rate survey to determineand set a specified prevailingcollision rate in a specificgeographic area, to report theresults of that survey to theinsurance department. Thatdepartment must make theinformation available uponrequest. The survey informationshall include the names andaddresses of the collision repairfacilities and the total number offacilities surveyed.

� Requires insurance companiesto provide each insured with anAuto Body Consumer Bill ofRights, which shall, at a mini-mum, advise consumers thatthey have the right to select acollision repair facility of theirchoice and that an insurer maynot require this work to be doneat a particular facility.

� Requires an insurer to inspectvehicles, either during the repairor after completion. The num-ber of vehicles inspected shallbe a statistical sampling suffi-cient to demonstrate to thedepartment the insurer’s effortsto reduce fraudulent collisionwork during a calendar year.

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Coolant Concerns–A Mix Of Formulas And Boiling Points

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Figure 1–Any coolant is better than the wrong type of coolant, but change to the recommended typeof coolant at the earliest convenience.

Servicing cooling systems has alwaysseemed straight forward, at leastwhen it comes to replacing thecoolant. Simply drain the radiator anfill it with a 50/50 solution of a nambrand coolant and water. What coulbe easier?

What we discovered, in the processof assembling a new I-CAR EnhanceDelivery program on heating andcooling systems, is that replacingcoolant has become more complex the past few years. This is primarilydue to the growing number ofcoolant formula variations. Anotherreason for the complexity, though noas critical, is different coolant boilingpoints based on elevations, requiringa different look at that 50/50 coolanwater mix.

The concern with coolants is that noevery technician servicing a coolingsystem is aware of these variances.

TWO COOLANT TYPES

There are two major types of cool-ant: propylene glycol and ethylene

glycol. Propylene glycol is availableas an environmentally friendlyalternative to ethylene glycol. It isnot used by the OEMs.

All of the coolant used by the OEMs,and most of the coolant available forrepairs, is ethylene glycol. Formulasof ethylene glycol vary by the addedcorrosion inhibitors, such as silicatesor acids, and long life additives (seeSidebar). Silicates act as abrasives towear off any corrosion before itprogresses too far. Acids chemicallyprevent corrosion from forming.

But replacing coolant is not as simpleas charting out the ethylene glycolformulas by vehicle make. This isbecause just about every vehiclemaker has a unique formula ofethylene glycol, that sometimes evenvaries by vehicle model. Using thewrong formula of coolant can resultin severe corrosion problems,damaged gaskets, cooling systemfailures, and even voiding of newvehicle warranties.

Color Means Nothing

Color is not a factor in distinguishingcoolants. Dyes give specific colors, butdo nothing to the formula. Coolantsmay be the same color, but be com-pletely incompatible. For example, thecoolant in DaimlerChrysler LH modelshas the same orange color as Dex-Cool™, but is a custom-made hybrid.DaimlerChrysler specifically forbids theuse of Dex-Cool™ in these vehicles.

Vehicle MakerRecommendations

The only reliable, fail-safe method ofdetermining which coolant to use isto check the specific vehicle servicemanual. For temporary use, such as aroadside emergency, pouring in anycoolant may be better than usingpure water. But the system should bethoroughly flushed and the propercoolant installed at the earliestopportunity (see Figure 1). Failure todo so can result in premature wear ofthe cooling system parts.

BOILING POINTS

Another concern with coolant is thevaried boiling points due to elevation.At sea level, the boiling point of wateris 100° C (212° F). Pure coolant boilsat 160° C (320° F). Coolant mixturesshould have a boiling point of about118° C (245° F). This is not achievedwith a 50/50 mixture, but a 65%coolant and 35% water mixture. Theboiling point of a 50/50 mixture is107° C (225° F). The 65/35 ratio alsoachieves the optimum freezing pointof coolant: -51° C (-60° F). A 50/50mixture will create a freezing point of-32 °C (-26° F). The boiling point is allthat changes with different eleva-tions. Freezing points of liquid donot change.

The Pressure Element

One reason why the boiling point isan issue is because when coolantboils it turns to a vapor, which haspoor cooling qualities. A biggerreason is because of increasedpressure in the system. Cooling

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ETHYLENE GLYCOL TYPESAND CHARACTERISTICS

Conventional American Coolant

� Contains silicates� Green or gold color

Conventional Japanese Coolant

� No silicates� Large amount of phosphates

(phosphoric acid)� Small amount of one or two

types of organic acids� Green or red color

Conventional European Coolant

� Very few silicates� No phosphates� One organic acid� Blue or yellow color

Organic Acid Technology (OAT)

� Blend of two or more organicacids

� No silicates or phosphates� Is contained in products such as

Havoline Dex-Cool™� May be an orange or pink color

Hybrid European Coolant

� Similar to conventional European

system parts, including the hoses andradiator, can tolerate a certainmaximum pressure for only a givenamount of time. The wear of someengine parts, such as the head gasket,can also be affected by too muchpressure extremes.

Boiling points change at differentelevations due to the change inpressure. Increased pressure increasesthe boiling points of liquids (seeFigure 2). Coolant is already underpressure due to the radiator cap. Aradiator cap rated at 15 psi is de-signed to maintain that amount ofpressure inside the radiator. Add thatto the atmospheric pressure, which is14.7 psi at sea level, and there’s atotal pressure of 29.7 psi that thesystem is under at sea level.

For every 1 psi of pressure, theboiling point of a liquid increases by1.5° F. If you do the math, it can bedetermined that a 65/35 coolant towater mix at sea level with a 15 psi-rated cap boils at 267.5° F. Using thesame calculations, it can be deter-mined that a 50/50 mix at sea levelboils at 249° F.

At higher elevations, the atmosphericpressure is less, but so is the boilingpoint. Consider Denver, Colorado,which is 1.6 km (1 mile) above sealevel, and where the atmosphericpressure is at 12.0 psi. This reducesthe boiling point of liquids by about10° F. The 65/35 coolant to water mixboils at 125° C (257.5° F), which is

anuary-February 2001

SEA LEVEL

Boiling Points At Sea Level(Higher Pressure = Higher Boiling Point)

Water = 100˚ C (212˚ F)50% Coolant = 110˚ C (230˚ F)70% Coolant = 120˚ C (248˚ F)

Figure 2–Higher elevations have a lower atmospheri

above the ideal 118° C (245° F).That’s good. But a 50/50 mix boils at115° C (239° F).

A technician diagnosing, setting up,and repairing cooling systems shouldknow that there are differences inboiling points of liquid at differentelevations. Sometimes the easy 50/50mix will not be the right choice. If thevehicle will be used for a trip throughthe mountains, a 65/35 coolant/watermix would be the best to keep theengine from overheating.

CONCLUSION

The concerns with coolant all relate tothe fact that an engineer designed eachcooling system to operate using a certaintype of coolant, at a certain optimumpressure. The specific coolant type ismost important. The recommendation isto use the type the vehicle maker wantsin the specific vehicle.

With coolant boiling points, keep inmind that vehicles have been operat-ing for a long time using 50/50cooling mix without a great amountof failures. If you hear complaintsabout overheating at high elevations,it might be wise to do the math onboiling points to see if you can twistthe laws of physics to your favor.

This information is included in the newI-CAR Enhanced Delivery Program,Heating And Cooling Systems Program1. Watch for it in your area.

9

DENVER, COLORADO

Boiling Points At 1.6 km (1 Mile)(Lower Pressure = Lower Boiling Point)

Water = 94˚ C (202˚ F)50% Coolant = 104˚ C (220˚ F)70% Coolant = 114˚ C (238˚ F)

c pressure and lower boiling points.

coolant� Large amounts of organic acids� Designed to have the silicates

provide the primary protection tothe aluminum engine parts andorganic acids protect for the longterm

� Blue or green color

Hybrid American Coolant

� Organic acid blend� Contains a moderate dose of

silicates� Green or orange color

10

Mechanical

New Approaches To CollisionAvoidance–Aimed At Rear Impacts And Reducing Injuries

Figure 1–Electronic eyes (top inset) scan the rear. A collision situation triggers alarms and seat belttensioners (bottom inset). (Courtesy of Ford Motor Company)

Collision avoidance devices we’ve seenso far are primarily designed to preventfront-end collisions. They do this byeither alerting the driver or automati-cally slowing down the vehicle. At leasttwo new systems, still being tested, takedifferent approaches. These systems areaimed at preventing and protectingagainst rear collisions, and protectingpeople outside the vehicle.

REAR COLLISION AVOIDANCE

A specially equipped Mazda 626, calledSensorCar, uses electronic eyes to helpavoid rear-end collisions. A pair of“charged couple devices,” similar tothose used in video cameras, is mountedin the rear bumper 60 mm (2.5") apart(see Figure 1). The data that is collectedis analyzed by a computer to predictcollisions. If a 9.5 km/h (6 mph) orgreater impact is predicted, an alarm issounded from the rear speakers toindicate where the danger is. A light onthe instrument panel is also lit.

This system also protects occupants incase a rear collision is unavoidable. Ifthe computer determines that acollision is imminent, signals are sent toactivate motorized seat belt tensionersto move the occupants closer to theheadrests (also shown in Figure 1).Studies have shown that the risk ofneck injuries is much lower if theoccupant’s head is within 100 mm (4")of the headrest. The motorized seat belttensioners automatically reset for reuse.The tests are trying to determine if thecomputer can reliably tell the differencebetween overtaking vehicles about tochange lanes and an imminent collision.

SCANNING FORPEDESTRIANS

The same test car has a laser mountedin the grille to scan for pedestrians in

front of the vehicle and warn the driverof a possible collision. Signals thatcome back from the laser are used bya computer to determine a person’sdistance and direction of travel relativeto the vehicle. The beam reflects backfrom a person dressed in black at45 m (147 ft) and from a persondressed in white at 60 m (197 ft).

The computer uses mathematicalalgorithms to calculate what is likely tohappen. A person stepping in front ofa stopped vehicle is in no danger. Apedestrian stepping off the curb intothe path of a vehicle traveling at64 km/h (40 mph) is in great danger.In this case, the driver is alerted by analarm sounding and a light on theinstrument panel, and the horn soundsto alert the pedestrian.

The system is undergoing testing toassure it’s reliable and doesn’t providefalse alarms before being put intoproduction. Estimates based on JapanResearch Institute data show thatserious pedestrian injuries could be

reduced by half with a driver alertsystem. Pedestrian deaths could bereduced by as much as 90%.

EXTERIOR AIRBAGS

The approach being studied by FordMotor Company to reduce pedestrianinjuries is similar to the protectionalready provided to vehicle occupants:airbags. A Ford Explorer has beenequipped with external airbags toprotect pedestrians.

Injuries occur to the hip and abdomenof adults or the head and chest ofchildren when struck by the front of avehicle. Head injuries can result fromstriking the back hood or cowl area. Byproviding padding to these externalareas of the vehicle when needed,perhaps injuries can be reduced.

One airbag, designed to providepadding on the hood, deploys from justabove the front bumper. It’s activatedby a pre-crash sensor and covers anarea 1.4 m (4.5 ft) wide and almost61 cm (2 ft) deep when inflated. Theairbag is 127 mm (5") thick. Unlikedriver airbags, which deflate in less than100 milliseconds, this airbag remainsinflated for several seconds.

An airbag also deploys from each A-pillar when contact is made with the

http://www.i-car.com

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front bumper. These cover the areaat the base of the windshield, andare fully deployed in the time it takesthe pedestrian to travel the distancefrom the bumper to the cowl area.Because this cowl airbag system usesa simpler sensor, it may be put intoproduction first.

CONCLUSION

These new types of collision andaccident avoidance technologies havemoved out of the lab and onto testvehicles. As they are refined andimproved they may be moved toproduction vehicles in the next fewyears. Future efforts include looking atside impacts and integrating thesesystems into the other safety systemsused on current vehicles.

nuary-February 2001

Volume XIV, Number 1

Editorial Office: I-CAR Tech Centre, N127 South Park Drive,Appleton, WI 54914, 920-749-0444, Fax: 920-749-0336.

The I-CAR Advantage is published six times per year andfeatures technical articles for the Collision Industry. Articlessubmitted for publication may not be used and will not bereturned.

I-CAR® is a registered trademark, and the Advantagetechnical newsletter is copyrighted by the Inter-IndustryConference on Auto Collision Repair (I-CAR). Unauthorizedcopying or distribution is expressly prohibited.

For permission to reproduce any of the contents in thispublication, contact the I-CAR Tech Centre at:

920-749-0444 or e-mail: advantage@i-car.com

Annual subscription rate: $29 in the U.S. and $34 inCanada. Other international subscriptions are available.

For purchase information or change of address notificationphone:

USA: 800-ICAR-USA Canada: 800-565-ICAR New Zealand:07-849-0159

Or visit the I-CAR website at http://www.i-car.com

CORROSION PROTECTIONAPPLICATION NOTINCLUDED

There is a paragraph in the article“Corrosion Protection Revisited” inthe September/October 2000 issuethat is being misinterpreted andrequires further clarification.

The paragraph in the second columnin the article states that “corrosionprotection requires a pre-repair plan.This step is not an additional process.It’s included in the repair times inestimating guides.”

This statement could be interpretedto mean that the application of anti-corrosion materials is the step that isincluded in the repair or refinishtimes. It is not. Application of anti-corrosion materials is not included inany of the major estimating guides. Itwas our intent to create the under-standing that the pre-repair plan orstrategy for the corrosion protectionsteps is included in the labor timesfor each step listed on a damagereport or estimate. It was not I-CAR’sintent in this article to contradict thep-page logic used in any of theestimating systems.

NEW SAFETY STANDARDFOR ELECTRIC VEHICLES

The U.S. Department ofTransportation’s National High-way Traffic Safety Administration(NHTSA) has published a newFederal Motor Vehicle SafetyStandard (FMVSS) to preventdeaths or injuries after an electricvehicle is involved in a collision.

The new standard, FMVSS No.305, will become effective Oct.1, 2001. It applies to all vehiclesthat use more than 48 volts aspropulsion power, have a maxi-mum speed of more than 40 km/h(25 mph), and a Gross VehicleWeight Rating of 4,500 kg(10,000 lb) or less.

Standard No. 305 specifiesrequirements for limiting batteryelectrolyte spillage, retaining thebatteries during a collision so thatthey don’t intrude into thepassenger compartment, andisolating the chassis from thehigh-voltage system to preventelectrical shock. Tests to demon-strate compliance can be com-bined with other crash tests.

I-CAR REGIONALCONFERENCESSCHEDULED

Every year, I-CAR hosts RegionalConferences to provide Instructors,Volunteers, and Staff the opportu-nity to meet and discuss issuesfacing their region. For additionalinformation and a registrationform, visit the I-CAR web site. The2001 U. S. Regional Conferenceschedule is:

Northwest Regional ConferenceJanuary 19–21, Mayflower ParkHotel, Seattle, WA

Southwest Regional ConferenceFebruary 2–4, Embassy Suites, BatonRouge, LA

Northeast and Southeast RegionalConferenceFebruary 9–11, Orlando AirportMarriott, Orlando, FL

South Pacific Regional ConferenceFebruary 23–25, The Orleans, LasVegas, NV

North Central and South CentralRegional ConferenceMarch 2–4, Holiday Inn SunSpreeResort, Gatlinburg, TN

The 2001 Canadian NationalCollision Repair Conference isbeing held: April 4–7 at the DeltaCentre-Ville Hotel, Montreal, QC

Also, join us at the InternationalAnnual Meeting in July 2001 inBaltimore, Maryland. More detailsto come.

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