ok guys, i have a 91 camaro, 5.0
i put in a new 4 core radiator with 12 inch fans and shroud, also new water pump, new 180 thermostat, new hoses, and flushed out the system, and she atays 170-180 at idle, but driving on hwy she gets to 220 and higher, i also did a universal trans cooler, and mounted it in front of the ac condensor, so its trans cooler, ac condensor then 4 core radiator, why is it staying so hot, i have fans wired direct so they run constantly,
should i relocate the trans cooler?
should i take off the fan shroud?
should i upgrade to better fans?
what to do next

i dont want to hear these cars run hot or anything about how the factory sets fans to kick on, cause i want them to stay around 180
there is no air in the system, i know how they are from the factory, and dont really care, i just want to get this down on temps, my guage works right too, so its not that,
im thinking its poor fans, or shroud not letting heat escape, or the trans cooler is making the rad hot and needs relocated?

whats your thoughts ?
i should be lower on temps wit all ive done, 4 core rad, new pump, new hoses, new thermostat..... ive heard these fans are not good enough, but wondering what to do before i pull the 305 and drop in a blueprint 396cid sbc, i want cooling issue fixed before i get a new engine too hot
also its a 305tbi with only 38,000 miles, and bone stock, so its not a hot running performance engine....yet....

 

Kudos for searching cooling threads before posting.

My guess is you dont have enough airflow through the radiator. You basically created restrictions by adding the universal cooler and bigger core radiator. You need very powerful fans and decent shroud setup with radiator properly sealed at the edges to force enough air through.

Edit: I'm assuming you have the lower air dam still in place too.

 

Here's a free test. Pull the grill, plate holder and fog lights and take it for a ride.

 

on my v8 s10 it would get hot while on the highway
i had to make an airdam to force air up into radiator, otherwise it was coming out the fans and going back into radiator.
hot air trying to cool hot radiaotor.
i bet you have something similar, because at high way speeds you should not need a fan at all.

i have a 66 biscayne im working on, i just showed this to the customer. No fan on radiator, and went for a 15 mile drive down the highway and back, to prove the cooling system worked, but he had issues with airflow.

 

Awesome pics man! I also see the airdam, that was my first train of thought, so I can discount that. The fans were fine from the factory as was the cooling system. The symptoms confirm it is an airflow thing, as it happens only on the move- from the factory, the fans stop running at over a certain speed, I wonder if you having them on all the time is helpful or not. It kind of rules out the rad and fans if it is working in traffic/ stationary. Could be a few things, some suggestions in order of what I think-

Airflow is key for these cars- trans cooler will not help, you need as much circ as possible
Check your timing- too much retard or advance can make them run hot

I think its less likely fans and rad as mentioned- the real test for these cars is traffic.

 

You've got an airflow problem not a fan problem. You said, "she atays 170-180 at idle, but driving on hwy she gets to 220 and higher...

The fans are doing their job at idle but something is going on with your airflow at highway speeds. Typically, cars have an easier time cooling while driving down the road at highway speed because of lots of airflow through the radiator. They tend to struggle at stop lights and slow vehicle speeds due to fans not being able to pull enough air through the radiator.

Last summer, my LS376/480, Tremec T56 Magnum swapped 1991 Foxbody Mustang coupe was tending to run a little warm on the highway (210-220F) but at slow speed below 40 mph, the engine temps would cool down to about 200-205F. Why? Because the PWM, brushless, C7 Corvette fan was pulling a huge amount of air through the radiator when it was commanded on at speeds less than 40mph. I posted this info online and someone asked me if I had my car's plastic airdam in place. I told them that I had it in the garage but not on the car. I installed it and what do you know? Now it cools better at highway speed (less than 200F) than it does with the fan running at slow, less than 40mph, vehicle speed.

People have already asked it your car has it's airdam in place. I can see the airdam in one of you pictures that you posted so I'm going to assume it's in place. However, there is more than just the airdam for routing air properly in a 3rd gen Camaro. Here is a picture of my 1987 IROC with the front cap removed:


Does your car have that black plastic piece that is right in front of the radiator in this picture? That plastic piece is routing the air where it needs to go for proper cooling. You gotta have it in place.

 

No, you absolutely don't have to have that black piece, only the lower airdam under the car.

The first thing I'd do is put in a stock radiator and see what changes. The 4 core is an answer looking for a problem IMO.

 

Why on Earth would you not need that black airflow guide? If it's not needed then why would GM spend the time, money, and effort to put it in their to begin with?

99.9% of the time 4 core radiators are a dumbass idea not matter what they are installed in. 3 and 4 core radiators are a dumbass idea in a 3rd gen as is any other radiator that doesn't fit for sh*t in the factory location and leaves a gap between the opening in the core support and the radiator big enough to throw a dog through.

 

Cool glamor shots of a Camaro on the road. Now post some actually useful pictures of you car's engine compartment, cowl to hood rubber seal, radiator bracket that goes from the core support over the top of the radiator, side views of the core support opening to radiator from driver and passenger side, air dam under the car, a down view shot of the front of the car from the bumper cover to core support, and any other pictures you think might be useful to figuring out your problem.

 

If you find a way to keep a 3rd gen at 180 all the time id love to hear it. I've had a handful of these cars over the last 25 years and never had it happen, even on v6 cars

 

Even modern-day 500+hp Camaros have a single row radiator from the factory...

 

I think that Airwolfe asked the best question concerning your statement.

In the 4th gen F body world, there are lots of factory, plastic air guides installed. It is advised there to make sure that all of those things are in place for proper cooling. When I rebuilt the AC system in my 2002 WS6 Trans Am, I made sure all the black, OEM air guides (or whatever they're called) were put back into place.

The OP hasn't been back in this thread to give us any more information on what's actually installed in his car.

 

To prevent debris from hitting the condenser. Anything heavy can't make the turn.

Mine was missing, I still don't have it, my car will not overheat in any condition especially with airspeed so it's not diagnostically relevant to this scenario.

My guess is poor / no sealing around the radiator combined with it being too thick acts like a wall and the air would rather go around it.

While we're at it, fans wired constantly is another mistake and makes zero sense from a hysteresis perspective.

 

That's definitely plausible.

I fully agree with the rest of your statements except I'm not sold on 4 core radiators being too thick to allow sufficient airflow through them. My car is undergoing an engine bay repaint and then a complete LS7/Tremec T56 Magnum F swap. I know that there was sealing foam between the radiator support and the radiator. It had two sided tape and when I removed the foam, all the tape stayed on the radiator support. I kept the OEM foam but I'll probably just buy new foam. It will get sealed!

I don't own a 4 core radiator but I do have a twin, 1.25" core aluminum, Cold Case radiator in my 1991 LS376/480, Tremec T56 Magnum swapped, 1991 Foxbody Mustang coupe. I installed this radiator about 6 weeks ago this radiator is the bomb! I can't believe how muchl this radiator cools my engine at highways speeds. I've got a 187F thermostat and at highway speeds with the AC on, 90F ambient temperature, the engine runs at 188-190F. The Cold Case radiator is chinesium for sure, but I'm really impressed. So much so that I've already purchased one for my IROC.

No reason to have an electric fan running at vehicle speeds above about 35-40 mph. My Dominator turns off my Mustan'g C7 Corvette PWM fan at speeds above 39mph.




Looking at this picture, it actually looks like the OEM foam seals the AC condenser to the radiator support. In any case, it helps funnel the air through the condenser/radiator vs around it.

 

I have a feeling if the OP replies back with pictures we might see something like this as in the thread below.

I have done everything and it still overheats in traffic - Third Generation F-Body Message Boards

 

I don't know why I like reading "cooling system" threads like what Airwolfe posted above, but I do. For anyone wondering but who doesn't want to read through the entire thread, the original poster solved his problem and talked about it in post #66. Sealing, baby! Sealing the gaps that allow air to bypass the radiator.

 

this is a must
i have a 1966 biscayne here in the shop with this exact issue.

if it over heats/gets hot while on the freeway that is a dead giveawy that the heat is not going through the rad.

$ core radiaitor is soo 1980 technology, ditch it and get a real radiator.

 

Another thing is people mistakenly believing that removing the cowl to hood weather stripping helps with cooling. It does at lower speeds but as speed increases the windshield to cowl becomes a high pressure area and air flows backwards into the engine compartment causing "Dead Air". Also same thing with aftermarket cowl induction hoods that are for looks only and don't seal to a carb of throttle body.

He might have everything under hood just fine and installed nicely related to the cooling system. Those aftermarket hood louvers might be causing the same effect and pushing air backwards into the engine compartment causing "Dead Air".

Can be checked with a high visibility color yarn cut a couple inches long and tape it around the louvers and seeing what the yarn does at different driving speeds.

 

Really? Then why do 2025 Camaros have single-row radiators?....

 

I think he meant 4 instead of $. He hit Shift + 4 and got $

 

There is no doubt that a 6th gen Camaro cooling system is very capable. That large single core radiator obviously has the potential to transfer a lot of heat at higher vehicle speeds. The ram air cooling track must be very well engineered by Chevrolet to flow plenty of air to the condenser/radiator.

The fan in those cars is one stout fan. It's a single, 18" PWM, 850 watt fan made by Spal in Italy. It's a monster of a fan. I own three of them; one is a genuine GM fan (linked below from Rockauto) and shroud assembly for a 6th gen Camaro and the other two are the fans themselves without the giant Camaro shroud. GM GENUINE 1581927 $322.89 from Rockauto as of today, 6/26/2025. This fan is the reason that these Camaros can stay cool at stoplights with that single core radiator.

I don't own one of these Camaros so I'm not familiar with the cooling system but I have looked up the dimensions of the radiator. They are square shaped vs the more traditional rectangular shaped. That 6th gen Camaro single core radiator works because of the entire supporting cooling system,



With the research that I've done for replacement aluminum radiators, I've found that there are a lot of choices out there. I ***think*** that the more modern engineering leans toward fewer but much larger cores. Two, 1" cores vs three or four, 1/2"-5/8" cores. Some of the bigger aluminum radiators have two, 1 1/4" cores like my Cold Case. During my research, I did find that some aluminum radiator manufacturers use multiple smaller cores like the old school brass radiators did.

I think that it would be very difficult to fit a 6th gen Camaro radiator in a 3rd gen. It would require a lot of radiator support modification. It would be giving up width for more height.

For me living in the Houston, TX area and running my AC during the summer, I'm going to run as much cooling capacity/potential as I can. These days, I believe that is a two, 1 1/4" core aluminum radiator. I'd be comfortable running a two, 1" core aluminum as well as I used to do in my LS Foxbody.

 

i watched a video on youtube, guy having same issue, and fans are only 800cfm, and 3000 required for a v8, so i ordered bigger fan motors, and also realize from the pics, i need to seal around the radiator, theres prob a half inch gap around the top and both sides, so after the fan motor swap, ill get it sealed with some foam tape, but i dont have the hood weatherstrip seal, seeing as how i have a tracspec louvers in my hood, dont see how it would help any, but i could be wrong

 

heres a few pics

 

thats all the pics i have sofar

 

Thank you, #dirtyeyez for posting the pictures of your car's cooling system. I noticed that you don't have the black plastic piece that I pictured in post #6. Komet did say that it's only there to prevent rocks and such from hitting the condenser so maybe it isn't needed.

Seal up your condenser/radiator and let us know the result. Hopefully, you get better cooling and you'll be done. If not, you might have to try to find one of those black plastic pieces.

I'm also interested in whether or not the functional hood louvers negatively affects engine cooling. I was planning on cutting my hood and installing the functional louvers.

 

i sure will let you all know, fan motors are supposed to be delivered by july 1st, so i should have it done a day or 2 later, from the video i seen, he was having the same issue, and he upgraded to the same fan motors i just ordered, im hoping that fixes it, if not ill keep going till i get it fixed
thank you all for all the help and info,

 

thanks again for the help and info, names david btw, cars named dirtyeyed after acdc song, and cars blue eyes, same as the wife
car is dirtyeyez, wife is dirty mouth, and im dirty mind, hahahah

 

The black swoopy plastic I believe is to prevent nasty road crap from being sucked up into the TPI airbox and separate radiator air from engine air. The carb and TBI cars didn't have from what i've seen. But they did have a closeout between the fascia and core support to keep air moving through the rad, rather than over it, and it appears you are missing it. As to the fan CFM, I moved from a pair of SPAL 800s to 1470s and, well, the big boys certainly needed to have their on/off setpoint adjusted. They're also so loud that I was rolling through the costco parking lot and I wasn't sure if people were looking at me because of how the car looks, how loud the exhaust is, or how it sounded like a DC-8 taxing to the runway as i was approaching them.

*edit* it looks like you have the closeout in one of the pictures, so nvm that, but 19psi on the rad cap seems way high. I think these motors were designed for 15psi.

 

you know, i was wondering about the cap too, had a built 355 in a 84mcss, and it overheated once, my dad told me that caps could make it happen, changed cap and never overheated again,,,, he old school street racer from 70s-80s

 

Oh, they absolutely can. Cap pressure regulates the boiling point of the coolant. If they're too low pressure or don't seal right, it'll boil rather than circulate. Too high pressure, well, hopefully you'll blow your hoses before your head gasket.

 

If that's the case (makes sense), then I agree with him...

 

so if fans dont cool her down, ill seal around the radiator and get a new cap, also thinking about using my old stock fan in front of the trans cooler to push air thru from the front, if that makes any difference

 

Fans do not cool your car at speeds of above approximately 35+ MPH.

You can literally, and I mean the word actually how it is meant to be used, take the fan shroud and cooling fans off the car and pitch them in the trash. Your car, if everything else is right, will never even know they were gone. It would actually even be better with them out of the way.

Back when I was young & dumb and broke too I had a 1979 Dodge D150 truck that had a 318 V8 automatic no AC and I had access to a rusted out 1978 Dodge Aspen 318 with AC and tailor towing package. The truck only had a fixed 4 blade fan, no shroud, no overflow bottle, and a 22" single core radiator. The car had a 28" 2 or 3 core radiator, 7 blade asymmetrical HD fan, a HD thermal fan clutch, and a HD water pump, a fan shroud, and an overflow bottle.

By eyeball it looked like it would all swap. It did like the factory put it all there except for me having to cut open the core support on my truck for the larger area radiator. Worked amazing.

Then the thermal fan clutch locked up tight as a drum and my truck sound like a jet about to take off. I removed the fan shroud, clutch and fan assembly and drove it that way for like 2.5 years until one day I replaced the defective fan clutch with a new one.

That truck never overheated. Not even in boiling hot summer with No Fan at all.

 

you think the shroud could be keeping too much heat on the rad? seems as the airflow is blocked by it to me////

 

As Airwolfe already said, fans don't cool off your radiator while the car is at highway speed. Ram air at highway speed provides way more air through the condenser/radiator than fans could provide.

Don't get ahead. Seal up your condenser and radiator and see how the cooling system performs.

 

Put the cowl to hood rubber weather stripping back on the car, make some temporary cardboard seals for the top and sides from the core support to the radiator and tape them on. Box in the opening around the core support to the radiator so no air can leak around the radiator.

Take the car for a drive.

I edited my reply above and added stuff about running No cooling fan at all.

 

Your radiator install actually isn't all that bad looking. Fits better than the other guys radiator did.

I'm going to send you a link when I find it again of a fellow third gen member on the site here that makes a nice upper radiator cover that will work with your radiator.

Your transmission cooler needs to be remounted or sooner or later your are going to get a leak in your AC system and you and the car will be hot.

You and your Dad need to make a mount for it that gets it off the AC condenser and gets rid of those through the core zip mounts.

 

Please post it in this thread. I and others may be interested in the radiator cover.

 

1982-1992 3rd Gen Camaro/Firebird – 9K Motors

LS Swap Parts – 9K Motors

 

You can seal off the radiator to the core support with expanding garage door weather seal. I do this and some other things you may benefit from in my old trans cooler thread:

https://www.thirdgen.org/forums/cool...oler-redo.html

Note: I've bought this stuff more than once and the second time it wasn't as dense. Try to get the thickest, densest foam tape you can.

Double note if you do read that thread: I still think about how I need to evaluate my actual potential and how my car is headed to the crusher .

 

Yes, i meant to type, 4 core radiators are 1980s technology.
I also stated the 66 biscane in the shop had the same issue, air going around the radiator and not through it.
I shoved in a bunch of cardboard to funnel air into the radiator and not go around it, and then reomved the 2 cooling fans and took the customer on a 15 mile test drive at 112 ambient to show him the outcome.

Now on the white camaro pictured, there is a huge opening between the bumper and core support at the bottom. fix some cardboard there to close the gap. I bet air is going down and under the car and not in through the radiator.

Heating issues suck, but you just got to use a bit of common sense. Air needs to go through the rad.
The factory seals and air dams need to be in place, and at one point the factory designed these cars to not over heat, got to get back to the simple basics and make it happen again.

 

Airwolfe, thank you for posting the links to the radiator covers. Those covers are really nice!

 

very nice, im going to order one

 

ok, well the new fan motors arrived today, i got them in, and took her for a ride, give her hell for a little, and then a steady cruise, the whole time she stayed around 180, pic posted below, i installed the plastic nose piece and swapped the fan motors to the pics below,the ones that came with radiator was 80 watt, swapped to 180 watt, so in all, i have a whole new system, 4 core rad, hoses, thermostat, water pump, and the new fan motors kept her cool, who says you cant keep a 3rd gen around 180 on the temps, very happy now, pics of rad and fan motor upgrade
and temp while driving, never got any higher....

also, the trans cooler has about a 2 inch gap between the ac condenser , not directly on it... but yes, will be relocated

 

#dirtyeyez, awesome to hear that your car is staying cool while going down the highway now!

You posted, "i installed the plastic nose piece and swapped the fan motors.... What plastic nose piece did you install?

 

i stole this pic from another thread, its the piece with the red arrow, i took it out so i could take the chin spoiler off when we repainted her, and forgot to put it back on......but now its back on, and everything seems to be ok now, but the outside temps was not too high yesterday, so im waiting for a really hot day to take her back out and see if the heat makes a difference, but i feel like its a problem solved , but im still going to move the trans cooler, prob buy a new one with fan made to it, and try it out, and also get some foam seal, and seal around the radiator better, but fans made a huge airflow difference and are no louder than the old 80 watt ones, the fan motors are 4 bolt, old ones was 2 bolt, i had to make some spacers (1 1/4 inch, from old transmission cooler lines, and longer screws) so the fan blade location is in the same location in the shroud as it was with the old motors, very easy to do with a tubing cutter, and old trans hardlines, and i think thats about it, but if i missed or left anything out, please ask, and ill let you all know how i did everything
thanks for all the help and info you guys, i really appreciate it

 

Thank you for posting the picture to show what plastic piece you installed. The car in the picture that you stole looks like a Firebird. I don't remember that piece being on my IROC when I started taking things apart. Maybe I just forgot or maybe my IROC's previous owner removed it. I'll keep this in mind in the future for when my LS swap is done and if the car doesn't stay cool driving down the road at highway speeds.

 

yes, my 91 has it, kinda like a funnel, to channel the air towards the radiator ill get a better pic of mine tomorrow

 

Awesome. That would be great.

 

Also with the air dam if it's fairly new or the car is lowered some it won't be able to do it's job effectively either. I had to cut an inch off for it to be more effective but I still think I need to cut a bit more off probs like another 1/2" and should be even better