My fan is always on.
Only when I am at idle, not moving, with the A/C on, my car eventually (slowly) overheats.

Wondering if I would benefit from a coolant system flush.

 

With the fans working, the next thing I would check is the thermostat. Make sure it's opening completely for full coolent flow when hot. Also, are you sure the water pump is ok?

 

Water pump should be fine, but the car was running a little warmer than normal yesterday in humid 90deg weather. I suspect that my coolant is a bit dirty because the stuff in the resovoir didn't look too good.

 

Well, it may or may not help your overheating but it's probably over due for a cooling system flush from the sound of it, try it and see what happens.

 

Is the fan running always with the A/C on? A/C on should make the fan run always, regardless of the actual engine temp.

Might try a new radiator cap as well - folks never think of the cap, but they wear over time, and don't hold the pressure like they should - it's a cheap thing to try.

 

Yeah fan was supposidly hardwired on by the PO. So the fan is always on from the moment the key is forward.
Strange that you say radiator cap....current one looks new.

I did the coolant flush today, and also cleaned out the dirty *** reservoir. I seen no difference in normal temp, but the temperate outside wasn't hot enough for me to test the a/c again. I will see if that worked. At a good note, my radiator looks pretty new, the metal jackets inside look clean as if it were just taken off the shelf.

Nothing notably dirty came out of my block, but it seemed there was too much antifreeze, and not enough water in there. The majority of the dirt was in the reservoir.

 

I have the same problem, changing the cap and thermostat.
I was just wondering what thermostat to buy, I know there are different one's.
I live in Az, so that might make a difference for what i should use.
It get as hot as 115 here. Any information on the thermostat would be great.
Are all the rad caps the same? Thanks

 

You could try a Napa gold. I think only 5 dollars or so. Maybe try drilling an 8th inch hole in the outer rim before installing. Give it a flush if your coolant is dirty.

 

I had another thought - might not help anything - but won't hurt. In front of the radiator is the condenser for the A/C - between the two is a space that just sucks up dirt, leaves, and other debris - might remove top radiator cover, lean radiator towards engine a tad, just enough to get the shop vac in there and clean out any accumulated gunk/leaves/etc.

 

ive had this same problem for a while, i put a 160* thermostat And a new radiator cap like 3 weeks ago. and still, at red lights, on a hot day here in sunny south florida, with my ac cranked up, my temp slowly climbs. it does seem to stay cooler longer than before though. i was thinking a system flush would help too so thats next on my list..

 

i have the same exact problem. i did away with the heater core and just ran the hose from the back of the intake manifold to the radiator below the radiator cap. installed new radiator and 195 degree thermostat as well as flushed the cooling system and purged all air from the system and had it pressure tested. with the cap off i have plenty of flow so im at my wits end. timing was done two weeks ago and i set it around 10 degrees. any suggestions would be great.

 

Your dirty coolant could have been some form of stop leak. Your radiator could have been partially plugged due to this. I've seen this before, so when you said dirty coolant that came to mind. Taxing the engine with the A/C could have pushed it over the edge of keeping cool, and it starts to get warm.

 

so i got underneath my car and reinstalled my air dam lastnite. made a huge difference and got a new radiator cap today so hopefully thats all it was. my fan is hard wired to by the PO and i still have yet to change it back but pressure testing is the best thing for tracking down any leaks. i had air getting into the system a month ago and it turned out to be the intake manifold gasket on the driver side.

 

You had no air dam?

 

That area is famous for sucking up all sorts of crud.

Stant 180° thermostat would be my recommendation. At 115° ambient temp, a 160 vs 180 won't make any difference as pretty much no car can maintain less than 180 at that temperature anyways.

Stant offers an economy, normal, and performance thermostat.....I got the top of the line one. I think it cost $6. No real difference. Just better materials.

Just about every radiator cap waill be a 15 or 16 lb pressure cap. I had trouble with a no name brand not sealing right. Bought the GM OEM replacement and it's worked perfectly ever since.

 

That doesn't make sense though since the dam doesn't do anything when stopped in traffic, it starts working at about 40 plus miles per hour, I am interested how you solved your overheating because i am almost at a loss with my GTA

1.Brand new water pump
2.New 180 degree thermostat
3.New a/c compressor (thought the old one was putting a drag on the engine due to bad sound)
4.Flushed out entire system with new anti-freeze
5.Brand new radiator
6. One new electric fan motor (thought they were worn out)

Only things left to do are the upper and lower rad. hoses and the belt (slippage?) the bottom one has the spring inside so i doubt its collapsing, the dam works because if the temp is almost on the red and i hit the highway the temp starts dropping, and the fans are rigged by the PO to run all the time and I even drilled a few holes in the thermostat, car only overheats with the a/c on.

 

ok i had the same problem. Replaced radiator,three different thermostats, waterpump, multiple flushes, then i went to advance and bought the largest elec fan witch was for a 7.3 diesel. Still had a problem, oh yea new a/c compressor, belt, and tensioner. i finally gave up and just didn't run my a/c. Then a couple months ago i got my convert. and noticed that my stock fan actually pulled more air than my 7.3 brand new electric fan. It's because the stock fan blades and thicker and wider, i replaced the fan motor from advance,, same blades new motor, and i now have a/c with no over heat. So the fan was working properly just not throwing enough air on the engine. Also guys, ive noticed alot of you saying you have hardwired fans, there not wired backwards right?

 

In my own opinion i think my fans aint pulling enough cfm's, I changed the electric motors on the drivers side fan but my temp still rises, i might just go changed the passengers side electric fan motor, i bought them at autozone i dont know if that makes a difference compared to the ac delco ones, i am stumped with this car, These cars were brand new back in the 80's and i am sure they didnt over heat straight out of the dealer with the ac running, so i dont see a reason in buying high performance parts for a stock car, the stock cooling system should more than suffice.

 

well thats what im saying i bought an over priced aftermarket fan when really it was just my factory fan that wasn't pulling enough airflow. but then again ive got the single fan on the front of mine. The only other thing that it could be is either the smog pump dragging which is very usual or you have a small head gasket leak or crack

 

I checked for air bubbles and white smoke but nothing, I might try changing the other electric motor and see what happens,

almost fed up with this car..

 

i know how you feel ive had four so far but im finally at the point of happy lol. if you have a leak small enough you won't be able to tell really. depends on where the crack is, change the other motor. if that doesn't work then only thing i can say is they make a head sealer called blue devil. it works awesome for blowed heads. good luck

 

Shot in the dark: Older thirdgens (and perhaps newer ones) had a spring in the lower radiator hose to keep it from collapsing.

JamesC

 

If i were you the next thing you should try is leak detector with a black light. Its possible you have a pinhole leak thats letting air into the system and heck it could be in the heater core.I would pressure test it and do the black light trick and im postive you will find your culprite!!

 

When I bought my `88 Iroc I also had over-heating issues with and without the air running. Here`s what`s worked for me the past 5 years. New Stewart stage 1 water pump, 180 thermostat, 200 degree on fan switch and the key was an LS1 dual fan shroud & fans. It took a minimum of fabrication to install the shroud. None of these ideas worked, water wetter and mixing antifreeze at 60/40 then 70/30, lower hose spring and 4 row alum.radiator. The dual fans and shroud from an LS1 made all the difference, along with the new pump and 180 stat. I also run a single row plastic/alum rad. and my temps stay at or below 200. No more over-heating issues. The Ls style shroud works better than the LT type.

 

Been doing a lot of searching here and on the net, Things that we should try is making sure that anti freeze and water mixture is correct. read the thread below

https://www.thirdgen.org/forums/cool...-required.html

 

I see we are driving the same car, your`s runs hot and mine does`nt anymore. I`d been driving El Caminos for 30 years when I bought this Iroc. Always did my own work and never had cooling issues with cars until I buy the Iroc. I spent a year trying different ideas about how to get the temps down. The last piece of the puzzle was the LS1 shroud and dual fans. My original wiring harness for the fans had been butchered so I got a new one from TPI Parts so it`s a clean install, looks almost factory. This car has`nt seen over 200 for more than a few minutes the last several years. There are some pics of a clean install like mine on here, it may take some searching. *****`s got alot of good info on cooling.

 

I think i am going to have to do the LS-1 Fan swap, car is driving me nuts, I wonder though, these cars from the factory floor never overheated, my car has about 85-90 percent of the cooling system brand new along with a new a/c compressor and it overheats while in traffic, I wish we could find out what makes them run so hot...

 

Sad thing is, it seems you replaced everything, but your engine lol. It is possible that the fan is not getting full voltage?

I switched from r12 to r134a since I posted this thread, and I haven't seen a overheating issue yet..will stay tuned for one of those 100deg+ days and let you know. My air duct temps are better, lowest I seen it get to was 58deg though, wish it was 33~ like it's supposed to be.

 

LOL I bet you any money If i were to replace the engine it still would overheat, honestly, i think the fans are not spinning to their full potential but everything seem to be wired correct thats the strange part, where could it be loosing voltage, my other gta the fans seem to spin slower , iam comparing it to my friends gta, so i could be wrong since iam not really measuring actual speed just audible speed...frustrated with this damn car..anyone want to buy it ? i paid 4,500 for it so anything above..lol

 

Seriously, get a meter, and check what the voltage is at the battery. If your fan voltage is anything lower than batt voltage, then you have resistance built up in one of the wires. It happens with time/old age, and moisture, it starts to coat the copper wire. Because believe it or not, electricity*(protons) runs along the outside of wires, not the inside of the metal. So when there is corrosion or GFS (Green fuzzy stuff) lol, it will cause a voltage drop, and your fan will spin, but not as fast as it should.

So essentially, if:

(0.1v difference is ok)
Battery Voltage > Fan Voltage = Something has resistance (could be the relay or connectors at fan/relay).
Battery Voltage ~ Fan Voltage = WTF?

 

The stock fans do go bad and when they do they wont pull the correct amount of airflow over the cooling fins. <which only work at slow speeds not highway>
Most of the cooling problems are from the fans being worn out. LS fans arent really any diff than the 3rdgen fans. Most likely the reason LS fans work better is because the stock fans are shot.

 

Try with your lights and heater fan on at night, Watch as your fan kicks on. If it is drawing too much the lights will dim, and your fan will slow down. I was told that by a mechanic friend when I was blowing relays. Have you blown any fan relays?

 

you could also put a 140 amp or larger Alternator on it that will help ya with a dimming problem but wont fix a worn out fan thats drawing 2many amps..

 

If the engine is overheating on the highway, the fan would not be the culprit if the air dam is intact.

 

Ikeepitreelz, if you want me to list what I did to my `88 Iroc let me know, it may save you some frustration.

 

I have a shot in the dark also. I read that a clogged catalytic converter can make an engine over heat. I thought of this since you seem to have no obvious reason for overheating. Could be worth investigating.

 

If you decide to do the LS1 fan shroud buy the entire unit, shroud and fans together. I paid around $50 for mine. I`ve seen alot of after market fans pushing, not pulling. Depending on how you connect the wires they will run either way. With your fans running put a piece of tissue paper or other light paper in front of the rad and it should pull it towards the motor, if not reverse your fan wires. I`m still running 200 around town without air and 220 with the air on. No overheating issues and I only need 1 fan running without the air on. These cars did/do run hotter than earlier models from the factory. Factory fan switch is 240-250 on.

 

Yes might help me, like i stated before, these cars were new back in the 80's and i am sure they did not overheat, what went bad thru the years? I have a new water pump,belt,thermostat,radiator, the bottom hose has the spring, new q/c compressor since the old one was making noise, new coolant,new heater valve, old one was leaking, ONE new fan motor, i am at a loss, car has excellent power, no pinging so iam sure its timed correct, only when the engine is under load (a/c on) will it overheat, if the needle is over 220 and i hit the highway the temp goes right down, so that makes me believe that its a CFM issue, right? BUT like i said one fan motor is new, I want to check if there is 12 volts coming out of the fan pigtail to see if iam getting full voltage. BTW car has no catalyc converter.

 

What temp shows on the gauge when it overheats? One thing I did`nt see that you replaced was the cooling fan switch, pass. side of engine above starter I believe. I use one from Summit, turns on around 200. Factory is around 240-250. I think that and a fan & shroud assembly from an LS1 f-body will have you happy and running cooler. You might check the brand and part number of the water pump you installed, ours are a reverse direction pump if memory serves me right.

 

Well here we go again. My car the other day, after driving for a couple hours, overheated very badly. It seemed the radiator cap was the culprit, so I went and bought a new one from autozone, and it was ok for a day or two, until today, without the a/c on, my car started to reach the red zone, and upon turning it off, I heard a bubbling or weird noise.

This obviously means I have a leak somewhere, but I don't have any smoke, and my engine runs perfect on start and wot. WTF, seriously.

I just replaced the radiator fan switch on passenger side, does anyone know what temp that kicks on? Perhaps I need a new fan for more cfms...

 

ANYHOW, I should report that I am running straight water as I'm not sure if I want to replace the fan switch (stock temp) to one that kicks on sooner. Perhaps adding a mix of anti-freeze will help?

 

I would drill a couple of 1/8" holes around the thermostat, and had water wetter to the coolant. I would replace the fan switch to one that kicks on at 195.

 

Here's one not one person has ever mentioned in any post I've read so far. Has anyone checked the condition and cleanliness of the condenser and rad. If you have a new rad. no probs. there, but if you have a old rad. the fins and tubes get caked with dirt and debris. Best way to clean is to take it out and clean with a tooth brush and castrol super clean or equivl. The condenser is more diff. to clean because of it being in the car, but clean it also and make sure the fins are not all bent up. This will reduce the air flow to our already struggling rad. If the fins are bent over you can use a small screwdriver, small paperclip, safety pin or something to that nature to straighten them out.

 

RyanEricW,

Who did the conversion of your car to R-134a? The 58° reading from the ducts, what setting is that? (MAX? NORM? Fan speed? Driving speed?)

What temperature or area of the gauge are you defining as "overheating?" Are we talking right into the red zone? Or in the 3/4 area of the gauge?

What temperature does it run with the A/C off? And in what traffic conditions?

Have you taken a look between the radiator and condenser? Even something as simple as one plastic bag in there will send the performance down the crapper. Regardless, they tend to look like the insides of a vacuum cleaner bag with all the dust and gunk in there.

I run the Hypertech 200/185° fan switch. Have run it for years. Both in mild Canada summers as well as scorching Texas summers. No point in running a colder fan switch, because if it's 201°, it's on. Works beautifully in wintertime (although I'm sure that's the last thing on your mind right now)

 

The bubbling is the coolant boiling in the overflow tank. Trust me. I'm fighting the same thing. Funny, I've had 3 other 3rd Gen Camaros and none of 'em overheated like this one (88 V6, almost identical to my 83 V6.)

RtR
www.chevyasylum.com

 

had the same problem, i replaced my water pump, it sure enough fixed the issue. cars runs like night and day