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Old 09-14-2002   #1
"Firehawk" GTA owner
Join Date: Oct 2001
Location: Brooklyn, NYC
Posts: 1,656

How hot does your GTA run?

The GM oil pressure and coolant temp gauges suck so unbelieveably that I almost believe that they are there just for decoration. How hot does your GTA with the L98/Auto combination run? Before I changed out my intake manifold gaskets, my collant temp would be 1/2 tick past 150* when at highway speed, and 1 and 1/2 ticks past 220* in stop and go traffic. Now after changing the intake manifold gaskets, at highway speed, my GTA runs 2 ticks past 150*, and 1 and 1/2 ticks past 220* in stop and go traffic. I changed out my thermostat with a 190* stat from Autozone. I didn't get the AC Delco replacement. Have I done something wrong here? Am i missing something, or is this normal???

BTW, I should also mention that my coolant temp gauge began to somewhat stick today. When I turn off the car, the coolant temp guage used to move all the way to the left past the ticks. Now when I turn it off, it gets stuck at the 100* mark and stays there unless I repeatedly tap the guage. Could this be the cause for my higher temp readings? How do I fix this problem? Thanks


1991 Trans Am GTA... Hopefully again
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Old 09-14-2002   #2
Multi-Vehicle Member
Join Date: Apr 2002
Location: Coatesville
Posts: 189

Hey again fred... Im taking liberty to answer all your posts tonight! I did the same thing as you with my thermostat...I changed it with an Autozone one. I have a 305, but the change was the same. I run alittle warmer when moving, but I run the same when in stop and go. I thought somethign was wrong, but the temp stayed steady, so I was ok with it. each "tick" on my car is like 12.5 degrees...i figured it out. so one more tick isnt too much more. dunno about the sticking...
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Old 09-15-2002   #3
GTA Junkie
Join Date: Mar 2002
Location: Marquette MI
Posts: 423

Fred....this is the second post of yours that I read tonight. It really seems to me that you need to head over to that friend of yours house and work on your prom

As we all know GM designed these cars to run HOT. The "Theory" was that the excess heat will burn off more harmful exaust gasses. I have yet to see proof of this, but it doesnt matter anyway I guess. This is my "cure" for the stop and go heat....

If you dont burn your own proms its expensive. You have to buy a fan switch from GM for like $45 bucks. It will turn your fans on at like 177 degrees, instead of the stock 220. That will keep your engine from reaching those high heat states, and will also prolong your engine life. Now if you do burn your own chips it a simple matter of changing the tables for fan control from 220 to whatever.

I myself installed a 180 degree 'stat and burned a new prom that turns the fans on at 185 and off at 180. The price for the flash prom was $5. Now the car runs at about 180 all the time. Highway, stop and go....all the time.
'88 Bright Red GTA.
Getting a full restore. EST. time of completion: FEB '06
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Old 09-15-2002   #4
Old Timer
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Join Date: Nov 2001
Location: Rincon, GA
Posts: 528

GTA Year: 1988
GTA Engine: 305 TPI Automatic
I had tried everything to get my temps to come down for a long time too. After a few $$$ the most significan improvement in controlling coolant temperature was when I changed the radiator. I bought a Modine from Advance Auto and it now runs very nice. On highway or cruise the temp will be as the picture below:
<img src="http://home.earthlink.net/~ozvresto/GTA/gallery/dash%20gauges.jpg">
On stop and go it might rise to one tick below the 220 and that's on mid/high 90s weather.
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Old 09-16-2002   #5
Join Date: Oct 2001
Location: Memphis Tn
Posts: 342


just exactly what do you mean burn a prom and where is it? i would like my car to run cooler what all can you do to fix this?
thanks tommy
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Old 09-16-2002   #6
GTA Member
Join Date: Jun 2002
Posts: 41

Burning a Prom is, Programming the EEprom chip in the ECM (cars computer) u can change values like the timimg curve, fuel curve, temp the fans come on and go off, (to burn Proms u need a Pocket programmer) But use caution with burning proms u can mess your motor up if u dont know exactly what u are changing, I have been learning about it for a while, I will post a few links to places to download the software/readme files and start learning, pay attention to the info on the RS232 cable, u will need to Make or buy, to hook your cars ECM to a laptop, and also u will need to buy a Pocket programmer to program the EEprom chip, so thats the principle, u Run the car, read the info (on a laptop) make changes as needed (with the pocket programmer)to the Prom, Run it again, Check the info again, thats how u dial your car in, here are a few places to get the software



so U will need a Laptop, and the RS232 cable to interface the laptop/software to the ECM (cars computer) then u go for a ride, read the info, and go from there, it is worth learning about, even if u dont burn your own Proms, the Diagnostic software is worth getting and using, if u look around u could buy a custom Prom but u need the info from your motor, u could get it with the moates Freeware, hope this helps
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Old 09-16-2002   #7
GTA Member
Join Date: Jun 2002
Location: North Carolina
Posts: 144

I had the same problems except hot in traffic and at speed. The heating problem in traffic was the connector and fan sensor had crumbled from fifteen years of heat and the fan was working only part time. My overheating at highway speed was due to damage to the front lower air dam from parking lot bumpers. There is an interesting fan upgrade listed at www.thirdgen.org/newdesign/tech/cool.shtml
that I am thinking about trying.
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Old 09-17-2002   #8
F-Body Member
Join Date: Jul 2002
Location: Pittsburg, Kansas
Posts: 237

though not a TPI car my TA has the exact opposite problem...it runs about 190 in town and then if I drive more than 10 miles on the hiway goes up to 220 and sits there till I hit town again. Kinda strange but it's never overheated on me.
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Old 10-07-2002   #9
Trish C
GTA Member
Join Date: May 2002
Location: California
Posts: 7

Cool Air dam

I purchased a new AIR DAM from the Pontiac Dealer, and all the heating problems were solved......it's a no brainer and Cheap $30.00
87 GTA....the white ghost---------------
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Old 10-08-2002   #10
********* at FL-THIRDGEN.ORG
Join Date: Feb 2002
Location: Summerfield , FL
Posts: 19

Cool temp

My 87 has a 180 therm, it runs a hair under the 190 mark on the digital dash, accept when I'm in traffic with the air on, then its just over 190. Not bad for this florida heat!
<img src=http://www.fl-thirdgen.org/bbgta1.jpg> Moderator at www.fl-thirdgen.org 87 GTA, 350TPI, 700R4, 3:45 GEAR, 3" EXH, FLOWMASTER, K&N, MSD BLASTER COIL, BBK AFPR, B&M SHIFTKIT, 1.6 ROLLER ROCKERS,JACOBS IGNITION, TPIS AIRFOIL, MODIFIED MAF
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Old 11-26-2002   #11
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Join Date: Nov 2002
Location: VA
Posts: 52

yeah, i'd agree with the 180* thermostat approach too. i did that a few months back, and it worked really well. the a/c runs well in stop & go in the summer, negligible difference w/ emiisions, no difference in gas mileage. heck, even the alternator seems to work a little better being 10* cooler.

in traffic, it never goes over the 220, and usually about a tick below it.

on the highway, still about that 150*/160* mark, that's mostly controlled by the front air dam though.
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Old 11-26-2002   #12
The Anvil
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Join Date: Nov 2002
Location: Vancouver, BC
Posts: 159

Fred, my '89 L98 runs the same temps yours does. My car is completely stock (but not for long, hehe.)

On the highway, they run cool. In traffic, as Rich stated the stock prom values has the fan coming on around 220, which is why the dramatic heat-up if you've been flying down the freeway with your boot into the radiator, and then when you make a turn off on an exit to say a fast food drive through, as you sit there the temps go up to about 220 before they stop climbing.

The chip programming deal as was mentioned above seems to me to be the way to go.

1989 GTA L98

Gunmetal metallic, L98, all performance options.
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