Hey everyone at TGO, I've got an overheating issue I've been dealing with for a long time of owning my 88 L98 GTA... Hoping someone here can help me out.
A few years ago I replaced everything - Factory replacement water pump, 180 t-stat, radiator, hoses + LS1 fans, lower temp fan switch/chip from Tuned Performance.

If I drive on the freeway without AC it will be between 190-220, but if I turn on the AC it can reach 230+... My Air dam is intact but looks kinda bent and I've read that maybe I need the 3 piece one? It's just a flat 1-piece, not the V-style I've heard about.
Here is a pic of 2 days ago, 94 degrees at about 70mph, that seems too hot. (I've checked the upper rad hose with temp scanner and the gauge seems to be correct with it's readings).

 

Here is a pic of the air dam, I think I'm missing 2 side pieces?..

 

Update, found I'm missing the 2 side pieces, as seen in this thread here: https://www.thirdgen.org/forums/body...installed.html
I'm going to buy them and see how it effects the temps.

 

Did you get the radiator hoses with the coils inside when you replaced them?

 

does your radiator hose collapse under throttle?

 

I can't remember if I bought coiled ones, but with the car off I was able to squeeze both hoses. So I'm guessing without coils.
While the car was running, I held the throttle open and didn't see either hose collapsing, both seem to have pressure preventing them from closing.

 

There is a whole system going on in that area, to direct airflow up to and thru the radiator, and also insulation to prevent it air from going around the radiator. Here are a few photos of what should be there.

 

Thanks for the pics LiquidBlue! I only wish mine was as clean as your's lol, I know I'm missing those 2 side pieces of the air dam and was lucky to find a set on ebay that I purchased today + new bolt kit from Hawk's.
As for other pieces I also noticed I'm missing the foam/insulation pieces that prevent the air from going around - I'll get some from Home Depot/Lowe's to close the gap.

 

I couldn't tell if you had the piece that is part of the bumper and continues up into that area - basically the 1st photo. One other thing to make check is your a/c condenser, make sure air can get thru it. all those fins can get mashed down over time and may need straightened out with a comb - both sides.

 

I'm not sure if those 2 pieces will make much of a difference? I think the main one is the middle piece. Try and see though.

I removed the upper duct work LB posted in favor of a tranny / power steering cooler and a pusher fan and so far no adverse issues. and i only have the main middle air dam....I hover at 220 at standing idle but it drops below that while driving...perhaps to cool actually lol



But yours is a T/A vs my Formula.... so Its possible those pieces are more important for it.

LB that is SOOOOOOOOO CLEAN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


If it still gets hot though, I would suispect an old tired radiator that may just need changing at that point.

 

I do have the piece that is part of the bumper thankfully.
Yeah the condenser is probably one of the few factory parts remaining and at this point I'm starting to suspect it.

I had the same thought that those 2 side pieces probably won't make much of a difference, but figured it was easier to just bolt those on first and scratch it off the list before I replace the condenser.

 

let us know how it goes!

 

I got the 2 side pieces on, and while it did seem to help a little bit it still gets a bit hot for my liking.
I'm beginning to guess the condenser as it is the only thing I have not replaced and the A/C blows very cold on start but gradually looses its cooling as the car gets warmer.

 

you can work on the condenser while it is still attached to a/c so you don't have to mess with the a/c. get a "comb" and carefully open up the bent cooling fins. its very, very tedious, to get to the other side, remove radiator. maybe while you are doing all that you will find something else like some old leaves, who knows...... Here is what I'm talking about. https://www.amazon.com/gp/product/B00ECV5Y9A/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

EDIT: btw - it sounds like your a/c is warming up because the condensor is not working - I say that because you are also over heating. once again points to blocked airflow. as you a/c runs, the condenser gets hotter and hotter, the fridgerant never cools off,, so its continually looping, never cooling off, then you start to get over heated. sort of adds up

 

Thanks for the link and information! So it sounds like the condenser might just be gunked up? Or is this an internal issue that would only be fixed by replacing it with a new condenser?

I found a new condenser on Amazon with good reviews specifically mentioning 3rd gens: for only $82 maybe it's worth it to just replace it and have it charged again.

 

I ordered that key set you recommended and some of that condenser cleaning foam as well.
I'll give it a shot first and see what's up.

 

Is your system still running R-12? Can't get it anymore, not easily anyway. If so, I would avoid messing with it if possible. Have you had A/C pressure tested to make sure it is in-line with specs? That could also be another reason it isn't working after a while. There isn't really anything to gunk up a condenser unless it has been not serviced correctly. The A/C oil can get old and maybe it can start gunking up I suppose, don't really know the answer to that.

I'd first start by making sure you have all airflow working the way the car was meant. These cars do run hot at idle, but going down the road, it should cool down pretty good. even in 95 degree weather. Mine actually runs cooler at idle with the a/c on because the 2nd fan is engaged.

Have you flushed your cooling system (including opening the block holes) and made certain the thermostat is functioning correctly? You could have some clogged water jackets that need flushed, or the radiator itself, but I'd still make sure your condenser is allowing air to flow thru. If you shine a light up in there, you should be able to see thru it and see the radiator.

If you end up having to tear open your a/c system, consider converting to R-134a - I was able to do it with good results. Some others not so good. I think alot of it depends on how tedious you are with the conversion.

https://www.thirdgen.org/forums/cooling/762352-r22-r134-conversion-here.html?ispreloading=1

BTW - Here is how a dual fan operates (1990)

fired her up, turned on the a/c (engine cold) both fans turn on.

turn off a/c, drive side fan remains on for about 1 min, then turns off

turn a/c back on, drive side fan back on, pass side off. about 1 min later, pass side turns on

ac off, temp now 110, turn back a/c on, driver side on immediately, pass side on in about 30 sec this time

ac off, temp now 120, turn back on, driver on immediately, pass side on in about 15 sec

ac off, let temp rise about 220, around 230, driver fan comes on. (seems too late to me in Austin) turn on a/c, pass fan turns on immediately

ac on, temp falls under 220, turn off a/c. pass fan off right away, drive side off in about 1 min

temp still under 220, a/c back on, both fans turn on immediately

 

The old compressor was leaking a year or so ago and I had a new compressor installed with R-134. I believe the previous owner had it converted to R134 because of the different fittings.
The only things I'm missing air duct wise is the small plastic trims that go on the sides of the radiator, everything else is intact and in good shape - I don't think those 2 small side pieces would cause the temps I'm experiencing however.

Both fans do turn on at the specified temps and with A/C. I have lower temp pass side sensor from Hawks & Tuned Performance chip with lower set temp.

At this point I'm guessing either there are coolant passages in the engine that need cleaning out/air trapped somehow in the motor or the condenser is causing air flow issues/clogged heat issues.

 

Well, first make sure your condenser isn't blocking airflow and after that you can take the next step. But I wouldn't rule out those side trims on the side of the radiator. The whole system is designed to bring air up, in and thur the condenser and then thru the radiator. All of that plastic creates a tunnel to make that happen. Hopefully once your overheating issue is solved, your a/c issue will also get fixed.

EDIT: BTW, since you are already converted to r134, then it would be easier just to take things apart IF IT TURNS OUT that your condenser needs attention. Just be certain to change out your drier and vacuum the system properly and if you change the condenser, add proper amount of oil back in. The orfice then used could be examined at this point, it could be part of what is going on with your a/c trouble. anyway, all of that is a entirely different issue. stay focused on your cooling problem first. a/c doesn't matter if you can't even drive the car!

 

For some reason my response wrnt into an old thread lol

How are your LS1 fans setup?

Are they wired with the stock dual fan wiring?

Are they both coming on?

 

I went to Lowe's and bought some condenser brush + cleaner kit. I'll try to tackle that in the next day or two.
I also went to my local junkyard and pulled some radiator side baffles from a 90s Buick (rubber/felt-like material) that I can trim to make it fit the side openings. Once that's on the air is completely set to only go through the condenser/rad.

Both fans do come on at the correct temps/AC and they are using the stock dual fan wiring (not sure if that was supposed to be changed).

 

If your ac got too hot ' didn't cool properly..., the pressure would get too high and cause the compressor to kick off and it would stop cooling.....does the ac stay cold:?
if the ac stays cold then I want to think its non -ac related but rather a deficiency somewhere in the cooling system. im personally betting on the fact that the ac turning on just brings out a cooling system problem.... Im on a computer rather than my phone now lol


Couple things id look at


1. pop the top radiator support / shroud and see if there's crud between the condenser and radiator and see if the radiator fins are clogged as well....although I don't think it'll be that bad / I don't think this s your prob but worth checking

2. is it the correct water pump you installed? 1988 so I think that's serp belt....so you'd need a reverse rotation pump

3. thermostat opening all the way?

4. Clogged / partially clogged cooling system....If you haven't changed the coolant sicne you did the pump might as well o it now as its time...flush it out, run water through it and see if gunk comes out....
- my S-10 had cooling issues for YEARS..... many coolant changers, t stats, etc... did not fix the issue.... flushed it out a couple years ago and black crud from I dunno what...sealer?? came out from the block...I hooked up a hose barb to the waterpump opening and flushed it....I was there for a few hours flushing black them bron gunk out.....never had a cooling issue again. somehow the gunk got dislodged and finally came out when I flushed it....

5. bad sensor for the gauge? My camry had a wonky sensor..itd read hotter than it was once it got to a certain temp.

6. Clogged radiator....if its old maybe you need to just replace or remove and back flush it etc... .could have hard water deposit that clogged the middle etc..

7. Do you have pics of your fan setup? LT1 / LS1 fans are supposed to be great. the motors are like TPI motors but are stronger and pull more air plus the shroud... others have plugged in the TPI wiring with no issues. So they should be able to cool it perfectly. did you keep the shroud I ntact?

 

Some good ideas in there. Guess I've been assuming you already looked at these things, but may be a bad assumption on my part. Another thing you can do along these ideas is after your car has cooled down overnight, open the radiator cap, and watch for the fluid to cycle. You should see it pouring from the top back into the reservoir once the thermostat opens.

As far as that cleaning kits goes, if its real bad, I'd just start with soap and water. Then, after making sure the condenser fins are opened up - they should all be vertical, pointing forward, and have about a 1 mm gap between all 10,000 fins (what ever the number is, thats why I said its tedious to unbend them) be sure to do it carefully, they are delicate and will break off. once you get that done, then you can use the other stuff, some soap and water will take you a long way. So will LA Totally Awesome.

 

For some reason. only now I am able to see some of your and LB other posts / answers like how the ac gets warmer etc... does the ac get cooler as you drive / freeway seeds? If so then you could just be low on refrigerant....134 gets warmer at stops in converted cars... I stil lfeel its not your huge problem though.


I can see the tubes in your condenser so I wouldn't think its that horribly clogged. Again, see if theres crud in-between the condenser and radiator.


Are your fans operating correctly ?They should blow pretty hard... I had a failing motor that would work but would not blow a lot of air as it was weak..replacing the motor made a huge difference in how the fan operated.

 

I've had a LOOOTT of cooling system problems with many cars over the years and have come across almost every possibility lol ..talk about bad luck.
Even had the impellers on a waterpump corrode to the point it would operate fine at city speeds but on highways it would overheat! My 87 actually is the best cooling wise...but I added a dual fan setup from a singel fan, plus a third pusher fan.



if it's original and his budget permits I say go for a new radiator, tstat and a massive flush and go from there. being almost 40 years its due for some maiantenance / upgrades

 

The AC does stay cold the whole time, however it does get a bit warmer when the temps are hot.
1. I cleaned that area out originally when I replaced the radiator, but I did check again and took a pic.

2. I believe the correct pump is installed, it is a Duralast CWP-715HD Autozone link (it does specifically mention Counter-Clockwise in the rotation).

3. I have not tested the T-Stat (using Gates 33008S, 180F, but if I drain the system I can buy another).

4. I definitely was planning to change the coolant soon. That makes sense especially if the passages are clogged up.

5. I believe the sensor is working, I've used a Infrared Thermometer scanning the top coolant hose and seems to be close to each other (but may be time to replace the likely original if that's the case).

6. Radiator was changed with water pump in July 2015, Spectra B750 (Autozone Link).

7. See uploaded pic

 

I definitely appreciate all the help!

 

well that def looks clean! that eliminates the clogging / dirt part i feel between the condenser......the radiator is also new / nice so thats probably not clogged either.... if the ac is cold I can't imagine its causing issues for your car to heat up. But clean the condenser like LB said.


I can;t recall if it was mentioned but how is your lower radiator hose? Is it soft / possibly it collapses and causes restrictions? .....that water pump looks like a reverse flow unit from the pics...i think the other units had all kinds of weird holes for brackets etc.. like my 87 did...



What I did for mine when flushing was i attached a hose barb, i think 5/8 barb by 1/2 npt to the waterpump plug...then I flushed it from there with that prestone coolant garden hose kit thingy.... I left the rad hoses on but pulled the t stat..and attached a hose from one of the heater hoses (no heater in my S-10) and let it drain from there...man the amount of crud that came out was CRAZY!!! I ran it just hose water and also with the engine running switching back and forth..... that loosened that gunk up......keep in mind i used to drain and fill it years before yearly at the radiator...even flushed it out from the radiator....coolant / water was always clean,....but al this gunk was stuck up in there somewhere... for YEARS apparently....

How is it temp wise in around town / idling? or is it just a problem on the freeway? Perhaps you do need to replace that middle air damn.....Good town temps but high freweway temps were an issue with air flow as I recall Trans Ams have cooling issues on the freeway cause the bumper hangs much lower..... but yours looks ok really.

it looks like you have a red wodner bar in there too!

 

I will clean out the condenser tomorrow and get the custom side baffles installed.
Lower radiator hose was also changed at time of radiator, it does not seem to collapse either.

I will have to flush it and report back my findings, thanks for the tips!
I've noticed that it does seem to run slightly cooler in city driving, like the lower RPMs allow it to cool off while on the highway it has a constant load and the cooling system can't keep up...
Yep! Red Wonder bar lol

 

Is the Serpentine belt routing correct? The reason I ask is because these cars generally have a heat soak problem in traffic, not on the highway.

 

Yes, it is the "long" 88 routing, if this belt ever snaps I'll swap over to the "short" 89-92 routing.
Yeah the fans seem able to keep up somewhat in city, probably because the RPMs are low.

 

If you are concerned about the possiblity of air trapped in your cooling system this will bleed it "after your car has cooled down overnight, open the radiator cap, and watch for the fluid to cycle. You should see it pouring from the top back into the reservoir once the thermostat opens. Also turn on heater during this process"

 

get one of those yellow coolant funnel things.... it helps you fill and kinda bleed the system...

Best...........invesment....ever......

 

Do you have a lower gear rearend? Like a 3:43 or something.

 

I ended up using some condenser cleaner foam and hosed it out, seemed to help on the drive today with AC Max doing 65-75mph for 10min on the highway then 15min of city driving. (Ambient was 87 degrees).
I bought some Prestone coolant cleaner/flush I'm going to run through the car over the next few days, drain, repeat, drain, etc, to see how that helps.

I'm honestly not sure what gears I have because I've never opened up the rear end.. It is a factory 9-bolt, I'm planning to when I order a diff cover from TA to change the fluid.
The rpms have always seemed a bit high for freeway imo.

 

Be sure to get a new t stat...just remove the old one and drive for long times with the cleaner inside for a while.....don;t leave the cleaner in too long though as they say it can eat stuff like gaskets up since its an acid or something.

I threw the cleaner in there with just water and drove it...left it for a coupel days ,max and drove it each day, and flushed it out and ran around with just water between cleans. I think I did like 3 - 4 cleans.

thats when all the junk actually started to come out...I wish I still had the video lol


How are your hoses and inside of your radiator?? ? Are they coated with some form of gunk?? Mine were covered in a rust brown looking gunk even though I had flushed it out before.....so i believe that was a sign there was crap stuck inside somewhere.... that and the fairly new t stat was covered in a rust looking haze. thats what prompted me to clean / flush

 

I noticed your RPMs in your photo. I have 3:43 gears and I am @ the same RPM @ 70. My car acts just likes yours, it always has. I also have a complete new stock cooling system. I always thought it was odd that it would cool down while idling at a traffic light. My car runs @180-190 around town but once up to cruising speed, I like to run 80 mph and my RPMs are up to about 2800, I go up to about 220. I have flushed and cleaned the condenser multiple times and I have just chalked mine up to the lower gear turning higher RPMs for the prolonged period of time. These cars were made to run hot and 220 seems normal so I never really worried but I always wondered why the cars cooling system acts this way.

You could find your gear ratio by lifting the rearend of the car, mark the tire and the driveshaft. Rotate the tire 1 complete revolution and while doing this count the how many times the drive shaft rotates. If the drive shaft rotates 2 3/4 turns to 1 tire revolution, you have a 2:73 or so ratio.

 

I just installed my LS1 fans last night and the ting stays quite cool at idle........ like in the middle of 100 and 220 with the ac on, so I think your LS1 fans should be cooling way beer than they are....plus freeway air flow? 230 is way too high...



it just came to mind, but have you checked your ignition timing??I recall looonnngg ago as a kid in auto class, the horribly old thick book we learned from said over advanced?? or was it retarded? timing can cause excessive heat and cooling problems especially on older engines.

 

LS1 fans vs TPI dual fans - Third Generation F-Body Message Boards


Also found this thread.... the last guy....


perhaps your LS1 fans are making it run...hotter??? lol ugh i hope not

 

I'll be doing the flush tomorrow and through this weekend, I'll make sure I don't run it in for too long. Everything looks very clean but who knows, maybe there is some gunk in the engine that's caked on the coolant passages.

Interesting, are the 3.43 gears stock? I'll definitely check that as well. Unfortunately my RPO sheet is nowhere to be found... I've been meaning to reach out to one of those heritage/archive sites to see if they can give me the info on my VIN.
I will have to report back what I find, maybe the extended high RPMs really are just the source of the heat. Maybe all due to the 55MPH national highway speed that was still around? lol

I have considered that, but if yours aren't causing you too many issues then I'm guessing something else is wrong with mine...
I did check the timing and it was correct for the factory setup (+6 I think).

If my issues persist after doing multiple flushes, new thermostat, etc. I may take it to my local shop that is good with older cars, (named Carbmaster, so they are pretty good with older stuff).

 

I haven;t got a chance to test on the highway yet since the car isn;t registered sadly lol

but the ac seems much cooler now too.


perhaps you should also consider condenser / pusher fans if all else fails?

 

Ahh that's too bad, I saw your side profile says Hawaii?

After flushing the coolant multiple times with cleaner/new coolant, new thermostat, cleaning the condenser, and getting those 2 side pieces of the air dam my car is actually running much cooler!
I still need to do a few more cycles and burp the system but it wouldn't go above the 190-200 zone with both highway & city driving.

Interestingly the 180 Gates t-stat I put in years ago seemed to sometimes open at 180... then sometimes open at 200+... My new Edelbrock 180 t-stat opened consistently at 180 during testing.
I'm guessing my coolant woes were a combination of gunk in the system and the t-stat being bi-polar lol

I appreciate everyone's help on this, hopefully this car never gives me temperature anxiety again haha.

 

Sweet! 190 - 200 seems ideal!

I guess gunk must have collected and maybe the t stat was just so so? Glad it's fixed!!

Yup in Hawaii! I just tested it around the neighborhood and it cools very well going up the hill etc.. with the LS1 fans / ac on....... if i just keep the ac on I don;t think myy aux fan will ever come on.....those LS fans suck a looot of energy though lol might have to upgrade my alternator!

 

Great to hear you are up and running! I'd still have a look at your condenser fins, that will help out with max a/c cooling too. Enjoy the ride!!

 

Yep! I'm happy with those temps for sure, I'm glad it ended up being something manageable before I went about replacing the condenser.
Cool, you get the ability to drive the car all year round with that Hawaii weather lol - I have noticed the same, if you find a good Alternator be sure to refer me to it as well.

I did take a look and most of them looked straight from what I could see. Definitely appreciate all the help!

 

I think you have the wrong air dam going on under there ,88 used a one pc. air dam on the Trans Am .I also use a one pc.

 

At idle / in drive with the fans / ac going and the headlights on and brake applied....I noticed the charging to be underdesireable....I tested it and let it idle a lot and shut it down and started it back up...battery seemed weak.......soooo Im guessing in this circumstance it could kill the battery.... that won;t happen a lot but still...........

Well, I was able to find a shop that will upgrade the CS130 alternators to a good 150 to 200 amps...but if I recall, when you do that you need to upgrade wiring etc?? I don;t want to do that...plus Id like to be able to get an alternator easily if mine fails...soooo what I am doing is I pulled the fans back out and i am replacing one LS motor with the stock TPI motor. It should cool plenty enough really though as the shrouds themselves make a huge difference!

 

 

I thought they changed it to a 3 piece later? I'm not sure but I was able to get the 2 side pieces off ebay and they matched up to my existing one. (Previous owner must have changed it).

I have noticed the weak charging as well.. Never enough to kill my battery thankfully but back when my fans were running all the time I definitely saw it on those hot evenings.

I like that idea! Did the TPI fan bolt up just fine?

 

Oh yeah, fits PERFECT...the housings are the same size etc..same connection...they just don;t spin as fast but i don;t think itll make a huge difference.... The LS motors are just higher amp units ad cost a lot more!


For the record, people said that LT1 fans are the same minus the design of the removeable shroud with vents....etc.... incorrect...the LT1 fan shroud is thicker and I don;t think it will fit as nice as the LS fans because of that.