GTA Trans Am overheats on grades

[bearphoto]

So I've got an 88 GTA Trans Am, w/ chev 350 engine. It runs fine with normal temps but when i pull a grade or its way hot outside the temp guage goes up toward the 220 + area. The temp will come back down when i level out. So far i have put a 180 degree thermostat in it. I pulled the radiator out the other day, it still looks good but im thinking about having it rodded out. I'd also like to replace the dual fan set up with something more efficient.

Anyone have any ideas why it heats up on the grades or when way hot outside? No head gasket leaks, coolant level was good. It the stock radiator just not big enough or are the dual stock fans not pulling enough air? Does anyone make a good fan replacement ?

[SpiderGearsMan]

Re: GTA Trans Am overheats on grades

clogged radiator ? the under radiator air deflector damaged ?
160 degree thermostat ?

[HoosierGTA]

Re: GTA Trans Am overheats on grades

I have an '87 GTA mine just sits around 200 degrees most the time if my memory serves correctly. Haven't really driven it in a year. It would be my theory that it won't make much difference in the warmed up temp even with a lower temp T-stat since the computer won't turn the fans on till the predetermined point. So I would say you need to fool the computer and turn the fans on earlier. O.K now that I said all of that a few thoughts popped into my head. One theair deflector under the radiator probably isn't the problem. If it is missing then you would get overheating when stopped or slow speeds. I've driven mine with no fans at 60 mph cruising speeds with no over-heating . So since yours is heating up under load I think maybe your fans aren't comming on. Let it heat up while sitting in the drive and see when /if the fans come on. Also one may take a long time to turn on . Like 220 or when the air is on. Maybe thats it,second one not comming on.Sorry for the book, but , I love these cars.

[fabricatordave]

Re: GTA Trans Am overheats on grades

thinking cloged rad or deflector gone damaged . it is probably best to replace rad then repair. repair you only get like year warranty .new is lifetime if you buy it from the right place and is probably about 150 or so . and the fans dont come on til like 220-230 range

[urwurznitmahre]

Re: GTA Trans Am overheats on grades

if the deflector is cracked. it be that.. been there don that

[Scott Liggett]

Re: GTA Trans Am overheats on grades

I thought those 3rd gens were designed to run on the hot side. Over 200*. It was a part of getting to them to run cleaner emissions wise.

[82z]

Re: GTA Trans Am overheats on grades

I thought those 3rd gens were designed to run on the hot side. Over 200*. It was a part of getting to them to run cleaner emissions wise.

They are. But it isn't that hard to make them run cooler. Find a set of fans from an ls1 camaro, get a switch that wil turn on the fans sooner, and make sure you have the deflector under the nose in good shape.

[Mr4Speed]

Re: GTA Trans Am overheats on grades

The heating up on grades problem has nothing to do with the fans-at anything over about 30 mph there is already more air flowing through the radiator than the fans can pull. It sounds more like the radiator just isn't getting the heat out of the coolant-or-for some reason there is too much heat getting into the radiator in the first place. Maybe air in the system too. Check to make sure that the a/c condenser isn't too clogged up with dead bugs and such.

My 88 has the same dual fan setup as yours and always runs right on the thermostat unless the a/c is on and then it runs one mark higher on the factory temp gauge. I run a 170 thermostat, mine is a 305 and not a 350, and it's a Formula so it doesn't have a front air dam and may be getting more air through the radiator(or not). There is an upper and lower deflector that work together to guide air through the radiator-make sure they're both ok. You can test the fans by letting it idle until the primary fan kicks on and check the temp on the gauge. The secondary fan will come on whenever the a/c is on. Mine seems to kick the primary fan on pretty early and I still have the stock memcal in the ecm.

My 91 Camaro had the single fan setup and it was very different. The fan didn't kick on until it was really hot and then it took forever to get it cooled back down after everything was heat soaked. I added a manual switch to kick the fan on early and as long as it never got too hot in the first place it would stay cool. You may have multiple problems like a weak radiator and a dead fan/weak motor or a bad temp sensor-there are two of them. A couple things to remember-the factory temp gauges are notoriously inaccurate, and they are also heavily buffered so that gauge moves really slowly. If you have the means to datalog off the diagnostic port you could see if the ecm is seeing the same temps that you are seeing on the dash gauge-the readings might be very different.

[TheSilverBuick]

Re: GTA Trans Am overheats on grades

Water pump? Head Gasket? Timing?

[min301]

Re: GTA Trans Am overheats on grades

Water pump? Head Gasket? Timing?

I've seen the impellers rot off, before the seals go
bad, or the bearings get noisy.

Head gasket...possible.
Timing. Good question...

I'd check airflow thru the radiator, and or a/c
condensor. Just follow thru... we'll get it figured out.

[tiresmoke!]

Re: GTA Trans Am overheats on grades

Only gets hot on grades......hmm.

Headgasket/timing would show up regardless of the incline/decline of the roadway......same with the water pump or lower air dam.

Surprised no one's mentioned checking the transmission just yet.....the standard coolers were integral to the radiator.

Old fluid, or worn components, could cause the temps to spike on a grade(from working harder than on level ground), thus raising the coolant temps trying to shed the heat......perhaps IndyShiftman could elaborate on this?

[91CCFirebird]

Re: GTA Trans Am overheats on grades

My lower air deflector is all but non existant as a previous owner hacked out the middle third of it. The car does have a 160 thermostat and a JET fan switch that turns the fans (both) on at 195 and off at 185. To this point it has remained cool, even on power tour.

[bearphoto]

Re: GTA Trans Am overheats on grades

Well i bought the car two years ago up in Montana. Coming home in the middle of the night i hit a truck tire tread and it ripped the lower air dam off. But it was so damn cold out it didnt matter. Once i hit Vegas coming home the car started to run hot so i stopped in vegas, bought some flashing, tin snips and a couple C clamps and made an air damn to get home. The car now has a brand new air damn on it but still runs hot. I did find out today the secondary fan is factory set to come on at 220 degrees which i thought was too hot. The radiator which is out of the car now appears to be very clean from what i can see. The thermostat is new and is a 180 degree stat. I will check the condenser for bugs and stuff this weekend but i really did not see any while removing the radiator. I have not checked the timing, the car is smokin fast although i did find one spark plug (passenger rear) so coroded over with ashen material it was probably the "miss" under load i was experiencing. I believe it probably has a valve guide that is letting a bit too much oil into the cylinder that it is crudding up the plug.

Other than the radiator/fans ect. i cant think of a problem. Now someone mentioned a second air "spoiler" that is above the lower one? Dont recall anything like that. I really appreciate the feedback. I will be doing a round trip of 5000 miles plus for the 2010 power tour.

[IndyShiftman]

Re: GTA Trans Am overheats on grades

Only gets hot on grades......hmm.

Headgasket/timing would show up regardless of the incline/decline of the roadway......same with the water pump or lower air dam.

Surprised no one's mentioned checking the transmission just yet.....the standard coolers were integral to the radiator.

Old fluid, or worn components, could cause the temps to spike on a grade(from working harder than on level ground), thus raising the coolant temps trying to shed the heat......perhaps IndyShiftman could elaborate on this?

I would think it would heat up more often instead of just on grades if it were the trans. However a torque converter clutch not operating will cause major trans overheating, then create higher temps in the radiator.

[TheSilverBuick]

Re: GTA Trans Am overheats on grades

Only gets hot on grades......hmm.

Headgasket/timing would show up regardless of the incline/decline of the roadway......same with the water pump or lower air dam.

Surprised no one's mentioned checking the transmission just yet.....the standard coolers were integral to the radiator.

Old fluid, or worn components, could cause the temps to spike on a grade(from working harder than on level ground), thus raising the coolant temps trying to shed the heat......perhaps IndyShiftman could elaborate on this?

I disagree with the thought that a corroded water pump, head gasket, or goofed timing always show up regardless of engine load.

Water pump may show up at idle and under load.

A head gasket ready to completely blow can show up only under load (check all plugs for this one after a good loading of the engine while warmed up).

Timing does funny things, but not enough advance if I'm not mistaken can cause overheating when under load, i.e. ~20* advance when it should be mid-30's, but can idle happily, or even drive under relatively light load with the low timing with out overheating.