Hey there everyone.

We have a 91 Camaro rs that overheats if you drive it for roughly more than 45 mins to an hour. We would like to take it on a bit of a road trip later in the year, for a day, not overly far in the grand scheme but far enough that we don`t want to risk it ovreheating
I know zero about vehicle repairs so even basic technical terms mean nothing to me.

with that in mind would anyone possible know/have any thoughts of the best way to find out the root cause & how to solve it please? Please i am not being horrible but plain laymans talk if you would be so kind

 

Define "overheating".

That's gotta be one of the vaguest, least specific, most overused, most useless words in all of the antique car hobby.

Tell us about the cooling system currently in the car. Is it all stock? what maintenance has been done to it lately if any? what radiator? what water pump? is the coolant somewhere between 50/50 and 70/30 distilled water to antifreeze? what type of antifreeze is in it? does it have any leeeeeeeks? when you checked the casting temp with your infrared gun thermometer, what was it ACTUALLY? (as opposed to whatever the gauge says) is the lower air dam, going across the front of the underside of the car directly below the radiator, intact and solid? etc. etc. etc.

 

Hi & thank you for your reply.

I have no idea what cooling system is in it, what radiator, water pump etc is in it. My girlfriend inherited the car after a loved one passed away suddenly. I`ve never used an infrared thermometer on it. The previous owner put a new floor in & rebuilt it himself 2 decades or more ago, he did almost all of the maintenance on it too.
I just know that there is a fan under the hood with a switch inside the car that turns the fan on & off, & when the temperature gauge gets too high, there`s a bit of hose under the hood & steam comes out.

 

I realize none of that helps any though, i am new to car maintenance, classic cars & american cars. The previous owner of the chevvy did the maintenance on our other car for us, i just helped him out, before that I used to just put previous cars in the garage for repairs.

 

If you can read, you can work on cars. Buy a Chiltons or Haynes repair manual and start with the troubleshooting. It will guide you through the steps.

Buy or borrow tools as you need them.

Since the cooling fan setup is already hacked up, that will take more effort to trace down. And since that has been done, I would be suspect of the quality of the other work.

First is verify the radiator cap is the factory rated one. Should be 16lb IIRC. Next you'll want to drain it and verify you have a proper and functioning 195* thermostat. The manual will explain how to drain the system and where to find the thermostat. While it is drained, I would personally pull the radiator out and clean between it and the A/C condenser. It's coming for road debris and mouse nests to be present there and cause a myriad of cooling issues. Some similar to what you are describing.

It is possible that you've blown a head gasket. A quick test for that is, with the engine completely cool (not having run in 4-8hr) check the top radiator hose. It should be soft and squeeze easily. Start the engine then check the hose again. If you've blown the head gasket, the hose will be rigid and hard to squeeze. This indicates a compression leak into the coolant system.

 

It's probably not the universal instant go-to bogeyman of "blown head gasket". Put that out of consideration until all else has been eliminated as potential causes of whatever problem you perceive to be happening. Yes it's "possible". Butt is it LIKELY? Not so much. Start with what's LIKELY before dredging up abuncha obscure worst-case doom & gloom and "maybe it's this maybe it's that".

More likely, it's "deferred maintenance". With such a vague description of ... something, it's IMPOSSIBLE to get specific as to any specific causes or remedies.

First off, steam coming from a hose, is NOT "overheating". It's LEEEEEEEEEKING. Whatever hose it is that's "steaming", or whatever other part it is, or wherever it is, needs to be replaced. Start with obvious things like that.

Second, people all the time seem to get into their heads abuncha CRAP like "I want it to run at 160°" or whatever, and then when that turns out to be impractical for whyever, they complain that it's "running hot", "overheating", and so forth, because "I think" "I want" independent of what the parts actually DO. Usually, IT'S NOT. These cars were built at a time when the factory was taking World War 2 technology (the small block Chevy engine was introduced in 1955) and attempting to graunch it into modern behavior and requirements, among which was, newly and continuously tightening emissions regulations. One way of reducing emissions is to get the engine's operating temperature up higher. This is not a Model T that you drive around without a radiator cap at all and fill it up out of the cattle trough when it runs low and pour oatmeal into the radiator when it leeeeeeeeeks.

Third, the problem with the higher temps was, that also increases cooling system pressure, and since the cooling system wasn't designed in the early 50s to withstand all that, it teeters on the brink of failure in the 2020s unless properly maintained. Paper and cork gaskets simply are inadequate to meet 2026 expectations. Consequently they require MAINTENANCE; which is, occasional replacement, especially when they FAIL.

Fix your leeeeeeeeeeeks FIRST. Find where the steam is coming from and fix it. Repacing the radiator cap is extremely good advice: those are designed to hold pressure, 15 - 16 psi typically, and if they don't, which frequently happens when either the rubber diaphragm that's supposed to seal turns to dust or the spring that's supposed to hold tension on it rusts away, you end up with abuncha SPEWING and such, which while it looks spectacular and is quite distressing, is NOT "overheating", in and of itself. Needless to say, if your rad cap is leeeeeeeking now and only holding say 5 psi, and you suddenly increase the system pressure to 15 by replacing it, the NEXT weeeeeeek link in the system, will begin leeeeeeeking. Seems a bit unfair butt that's Just The Way It Is. You just gotta fix the leeeeeeeeks as you come to them.

Once you get the leeeeeeeks taken care of, the next things to look at are:

1. Air dam below the radiator. These cars don't feed the radiator from the front, like through the "grille" since they almost don't even have one of those; they feed it from the BOTTOM. That air dam creates a high pressure zone in front of the radiator near the ground, and a low pressure zone behind it, as the car moves. Since the cooling air has to move over the radiator from an area of higher pressure to one where it's lower, and fails to move if there's NOT a pressure differential, that's THE FIRST THING which by its failure will cause the system to work inadequately at highway speed.
2. Coolant mix. Everybody hallucinates that water boils at 212°F. IT DOES NOT necessarily. The truth is, PURE water, AT SEA LEVEL PRESSURE, boils at 212°F. Antifreeze NOT ONLY lowers the freezing point of the coolant mix, BUTT ALSO raises the boiling point; essentially, it keeps the water LIQUID over a much wider range of temps, both colder AND hotter. Pressure also raises the boiling point, ALOT, which is why when a cooling system has leeeeeeeeks, it SPEWS: leeeeeeks allow pressure to escape, thereby LOWERING the boiling point of the coolant. The boiling point of a 50/50 mix of pure (distilled) water and antifreeze, at 15 psi, is about 270° or therabouts. The AF and the pressure are each responsible for about half of the difference between 212° and 270ish°. If either one goes away, you can end up with boiling, even if everything else is right.
3. Water pump. There's a little impeller inside it, that's made of steel; it rusts, and slowly disappears. More insidious, the coolant in it cavitates, meaning it makes tiny bubbles due to the pump's action on the pressures, and when those bubbles which form in an area of lower pressure move into an area of higher pressure, they collapse; and when they do that, it's like little tiny hammers constantly beating on the impeller. The impeller actually ERODES because of this, and over time, becomes less and less effective. Water pumps also leeeeeeek, particularly where their shaft comes out through their bearings and the pulley bolts onto it; there are seals to protect the bearings, and when those wear out, the coolant escapes through the bearings. (which isn't particularly good for the bearings either) Problem is, it's behind the pulley, so you mostly don't see it. Instead, the coolant drips onto the back side of the pulley while the engine is running and becomes a fine mist, which then gets slung ALL OVER the engine compartment. The only visual evidence of it is MAYBE a buildup of rusty looking residue everywhere and a constant aroma of coolant, and coolant running down the back (underside) of the lower radiator hose when the engine is hot and not running. So if you get up under there and LOOK UP at the bottom of the rad hose, and you SEE a trail of a drip running down the back of the hose there, you need a water pump.

This isn't Harry Potter, where someone says one magic word ("overheating") and somebody else can say some other magic word ("head gasket" for example) and the problem disappears. You gotta actually LOOK AT the car and see what's wrong with it, and then fix it. We out here can't see it, especially not with its hood closed. YOU have to be the one to do that.

 

I'm with sofa on this. It is possible that he has a blown head gasket but what made you so quickly jump to this conclusion? Are you trying to scare this poor guy off?

The radiator hose will also be hard to squeeze in a perfectly functioning cooling system because the cooling system is pressurized! This is normal!

 

Chevvy1991, can you post some underhood pictures? Maybe in one of the pictures you could show us the hose where steam comes out of.

 

Call a local shop, and go get a radiator flush done.
Then post up several pictures of the car from the front, sides, and hood open so we can see what is there, or might not be there.

It's be pretty simple

 

That was my first thought as well. I remember when my 1980 Z28 was about 8 years old. I had changed out the cam, added an aluminum intake and headers. I noticed that the engine was starting to run warmer than before. At first I tried to justify it by thinking that I added horsepower and that resulted in more heat.

After staring at the temperature gauge for months, one day I removed the radiator cap (cold engine) and looked inside. My OEM, 3-core radiator had a ton of white, calcium looking buildup clogging all the tubes ! A lot of buildup!

Back in those days, you could buy a really good Prestone brand of "Super Radiator Cleaner." This cleaner required you to flush all old antifreeze and run it with plain water for up to 10 hours. It used the engine heat to help do its cleaning. After 10 hours, I flushed it again and all of the white buildup was gone. The radiator was clean. I added antifreeze and the engine was back to running more normal temperatures.

These days, it seems like no one really cleans a used radiator. I think that most people just buy a new replacement. I just went to Rockauto.com and looked up radiators for a 1991 Camaro. Most of them were puny, 1-core radiators, 1" thick. Some had a core 1.25" thick which is better but still puny.

 

Nope. It's a quick, easy test to see. It's one of the first tests I do on any vehicle I drag in or have issues with. The hose will be hard to squeeze EVENTUALLY in a properly operating cooling system, but not immediately upon a cold start UNLESS the head gasket is allowing compression into the cooling system and pressurizing it.

I'm not saying that it is bad. But for someone with limited tools and knowledge, it is an easy test that requires no purchases and can save days of other troubleshooting if it does prove there is an issue with a head or head gasket.

Additionally, the cooling fan is hot wired to a switch so we KNOW at some point in the past, there was another cooling issue of some sort. We do not know the severity, duration or root cause of that and that is always a reasonable suspicion of a major overheat which can lead to warped or cracked heads and head gasket issues. I'm not trying to scare anyone. But first things first, let's see if he's going to be chasing his tail looking for other issues.

He's gonna start it to do many other checks and tests so it's not like I'm asking him to just junk the engine. Withe the engine cold, put the hood up, start the engine, feel the hose. If it's soft, move on to other tests and checks. If it's rock hard instantly, the heads need to come off and there's hours of other tests he doesn't need to do. I'm kinda surprised there's this much push back for offering a suggestion for a simple test. I did t say "IT'S GOTTA BE THE HEAD GASKET". I just said here is a simple test that can help you eliminate it as a possibility without having to buy a bunch of specialty tools and chemicals.

 

If the rad itself is gunked up, I've had good luck with throwing distilled white vinegar in and sloshing it around outside of the car. I did this with a '70 Z28 rad back in college, was completely filled with mouse nest when I got it (and a couple corporeally departed inhabitants ). I was originally using that radiator for a computer watercooling setup for overclocking competitions, so I had to make sure it was 100% clean inside before I put it to use... side note, but 2ndgen rads are GREAT for PCs since they're entirely brass/ copper Put about half a gallon of vinegar in, sloshed it around for like 10 minutes, dumped it out in my dorm room shower, filled it with water, and repeated this a few times. Think I ended up going through 2 gallons of vinegar before it came out perfectly clear. Got the radiator very very clean, and never saw any signs of gunk or buildup in the year and a half or so I was running that in my computer's loop. I ended up throwing this rad in my thirdgen a couple years ago after a plastic end tank on my stock rad popped, 2 days before I had to go 4 hours north for a 3 month work arrangement in Ocean City MD. I was able to get the '70 rad to fit (same size/ location for the hoses and trans cooler lines!), and haven't had any issues with it in my car for the last 2 years now. I check the coolant in my rad every couple of weeks out of habit, still perfectly green.

Long winded, but goes to show that you can still get a radiator clean without anything super fancy. Not sure that I'd recommend dumping vinegar in the rad while it's in the car, but works great on the rad at least. I think they do still sell Prestone radiator flush, but it's gonna be a bit more pricey than vinegar. Chances are though, if your rad is gummed up, you are probably gonna want to look into cleaning the rest of the cooling system as well....

 

I used the $14 Prestone cooling system cleaner and distilled water in my Jeep for about a week in the summer to clean out the gunk in it. It seemed to work really well. LOTS of trash came out.

I do suggest pulling the lower radiator hose to drain it and then flushing the radiator out with the garden hose instead of trying to drain it through the radiator petcock. There can be some pretty large pieces in a really dirty block.

I also flushed water through the heater core in the opposite direction of normal flow to knock anything in it loose I could.

 

Oh. Okay. If the radiator hose is firm immediately, the blown head gasket is pressurizing the cooling system. That definitely makes sense to me. Now that I understand what you were saying, I think that this is a good, easy test for the OP to start with that will literally only take seconds to do.

The OP hasn't been back in this thread. I think he's already feeling he's in over his head. Hopefully he'll come back into this thread and we can help him find the car's overheating problem so that he and his girlfriend can drive and enjoy a cool 3rd gen Camaro.

 

sleeper84, thank you for letting us know about your radiator flush experience. Did your radiator have a lot of white buildup clogging your radiator tubes before the cleaning?

 

Old cars of any form can be intimidating, I've watched a lot of nice projects go undone because of getting overwhelmed or falling in love with the idea of a project before you fall in love with the car.

I try very hard to keep the people I talk to grounded and on a straight course. Getting them running and driving is always first and foremost for me. Even if they are rough and ugly. You've got to love the car to make it worth the time, money and effort we put into them.

I really hope they come back and get it going. One more saved from the scrapper is always a happy day.

 

There was every color of buildup imaginable. Being a Jeep, there was corrosion from age, and it honestly looked like at some point the had needed to fill it with creek water. Tons of rust and flakes from inside the coolant passageways and other debris.

It was partially for naught as the top radiator tank exploded 3 weeks later but the system was much cleaner when I had to drain it to replace the radiator at that time.

​​​FWIW, I flushed everything with tap water from the garden hose then poured gallons of distilled water through after to purge it. Then added a full gallon of 100% antifreeze and topped it up with 50/50 mix. After a few days of running, I checked to make sure I was near the 50/50 ratio for winter use.

 

Creek water!!! That was a dirty cooling system. It sounds like the modern, $14 Prestone cleaner does a pretty good job on a dirty cooling system.

 

Thank you to everyone that`s replied.

I have taken some photo`s of the engine bay for those more knowledgeable than us.

 

for context the most we both know is how to check & top up the fluid levels. I can change bulbs & fuses though. I`ve never really done any vehicle maintenance myself, the previous owner last year did supervise me changing a front wing on our other vehicle, but had to talk me through how to do it & come & check. Though he was dying at the time, we just didn`t know it then. We really want to keep the car in his memory & make use of it, if we could get it resprayed we would like to take it to local shows too.

 

I hate to be that guy, but from the pictures I'd say a little steam is the least of your concerns. Somebody correct me if I'm wrong but that appears to be a carburetor bolted to the top of the fuel injected intake manifold. There also appear to be three extension cords hanging by the fans that look like they are probably connected the headlights. I honestly don't know where to begin with something like this.

 

Pour 5 gallons of Kerosene on and inside of the car and pour a trail of Kerosene leading 20 feet away from the car. Set the Kerosene trail on fire and run like Hell.

Kerosene NOT Gasoline.

If this guy ever worked on any of your other cars you might want to get some more 5 gallon jugs of Kerosene for them too and burn them to the ground also.

 

I'm surprised the car didn't catch fire and burn the previous owner alive. Don't ever get in this car again and start or drive it unless you want to join him in the afterlife.

 

This can't be for real right?

Just an old long time member with a new account "taking the **** out of us"?

These pictures are all just AI right?

 

I just about burst into laughter when I saw the pics.

But seriously, its definitely the head gasket.

 

The head gasket may be the only thing worth saving.

 

I blame Richard Holdener for this. He put a Holley 4 barrel carburetor on top of the plenum of a Tuned Port Injection engine.

 

I couldn`t say to be honest.
I know the previous owner was a bit of a mad scientist/evil genius type person, but in a good way.

 

I am 100% going to use the car again & again & again.
No I am a genuine new member & the photo`s are 100% real.

The previous owner didn`t care how things looked, they just cared about them working.

 

This car is a Death Trap that will maim or kill you or someone you love.

Push it out into the yard and use it as lawn art. A conversation starter maybe.

Don't ever start it or drive it again.

The only person that understands what is going on under that hood is gone now. No one here on this forum in their right mind can help you with this car.

 

Idk what's more impressive, the fact that the motor even starts and runs like that or OP has taken it on *multiple* almost hour long trips.

Anyway, it's overheating because the fans are on the wrong side of the radiator.

 

Holy smokes Batman, I was NOT expecting to see a carb bolted to the top of a 3.1 like that honestly kind of impressive that it even runs. I think someone on this forum did something similar (or at least tried to) using an Eaton M90 supercharger bolted to the top of their V6 intake like that, but.... wow. I know you mentioned that you weren't really good with vehicle repairs, so I'm wishing you the best of luck, that thing looks like an absolute cobbled nightmare. Ignoring everything not related to the cooling system for the time being, I do also see that the coolant overflow tank appears to have been ripped out, which could be an issue. If you look next to the radiator cap, you'll see that little hose sticking out. Basically, when your cooling system starts to get hot, the pressure pushes the spring on the radiator cap up, and coolant comes out of that barb. From factory, that line ran to a tank on the pass side fender (mirrors the washer fluid tank), and that's where the coolant would go. As the car cools down, fluid gets sucked from that tank back into the radiator. I don't think that would cause all of your overheating issues, but if that line isn't running to any kind of container, then your fluid may just be dumping out on the ground when it gets hot.

As exiled350 mentioned as well, the fans MAY be on the wrong side of the rad. From factory, the 3.1 would have one big 16" fan mounted on the engine side of the radiator, instead of 2 fans on the bumper side. Now, they DO make pusher fans, which WOULD bolt to the bumper side of the rad, but you'd have to look at the direction of the fan blades to see if the guy put the right kind of fans on. If those are puller style fans, then they're doing absolutely nothing for you mounted on the bumper side. THOUGH, in a 3.1, the fan shouldn't be kicking on at all while the car is moving anyways. In a well functioning 3.1, the air that gets forced through the rad is more than enough to keep it cool while on the move, and the fan only kicks on when you're sitting in traffic. If those are puller fans though, and if they're wired to run off a toggle switch or something, they'd probably be creating some kinda negative pressure situation that prevents air from moving through the rad effectively while on the move. If you can switch the fans off, try to keep them off while you're moving, it may help.

EDIT: Looking at the direction of the fan blades on your fans, those do actually appear to be pusher fans, so those may not be your issue. Total shot in the dark here, but I wonder if the car is running too lean.... usually when someone goes and bolts a carb to the top of their FI intake like that, the original throttle body (where the air comes in the front) is blocked off. It looks like your motor is pulling air through the carb AND the original throttle body..... the fact that this thing runs really is a testament to the tenacity of the 60degV6 very possible that it's getting too much air, not enough fuel.

Good luck with the rest of the car, truly. I don't want to try to be a downer about it, but this is gonna be one humdinger of a project for you. I respect you keeping the car alive in the guy's memory, and honestly I'm not even really that upset by the whole carb situation.... it's just gonna make it a significant challenge for you to keep the car running with all that's been changed. A factory service manual isn't really going to help all that much since so much has been changed, and God only knows what the ECU might be doing (if it's even still in the car), but hey.... it runs for now, so that's a start. A factory service manual WOULD help if you wanted to put the car back to stock with a replacement intake, but that'd be a pretty significant undertaking, and you'd probably have to rewire most of the car.

 

Definitely didn't have this on my WTF bingo card. Aside from all that has been mentioned, there looks to be some significant rust on the driver's side near the firewall. That's a sign of potential significant rust on other areas of the vehicle.

 

True, good eye.... another thing I noticed is how sooty the pass side of that motor is, and I have a pretty good guess as to why.... that tube behind the alternator is for the EGR. Usually, that bolts up to the side of the neck of the intake, little 2 bolt flange. Odd to me that it's just hanging out like that since the rest of the emissions system is seemingly intact, but it definitely looks like it's just spewing exhaust straight onto the alternator area. Now that I mention it actually, wonder if that's also contributing to the overheating.... probably not, considering that the ECU likely isn't doing anything at this point, but might be worth hooking that back up to the intake and seeing what happens. At minimum, that tube should be blocked off so you don't have a massive exhaust leak in your engine bay. Looks like the EGR itself is unplugged, but exhaust is still going to be going through that tube. Hope the previous owner at least put a block-off plate on the side of the intake as well, else you're gonna have a pretty good sized vacuum leak.

 

OP: You don't have the tools/skills or knowledge to fix this car and all of it's (many) issues. I think that you need to re-assess your ownership of this liability.

 

Thank you for the pictures.
There is no way you, nor I, could have described that with words.
Now where you go from here is going to be a bit of a fun trip.
Are you ready for a V8 swap?
Might be the best route to take is to remove the current drive train and 'start over'..

 

This pretty much sums it up.

Not to be a jerk, butt, a 91 is an ANTIQUE car. May not feel like it, butt it IS. Daily-driving an ANTIQUE car is always risky, even for those who know them well, understand them, have tools & spare parts, and can be tolerant of unreliability. If you lack those resources, trying to drive such a thing is a recipe for finding yourself sitting by the side of the road in the most inconvenient places (that's ALWAYS where it happens) at the most inconvenient times (which is ALWAYS when it happens).

An ANTIQUE car that hasn't been maintained in its past just magnifies all this. Worse, a hacked-up blibbet like that thing - that's WW2 slang for 10 gallons of excrement in a 9-gallon bucket - (a CARBURETOR on top of the intake plenum!!!!! with a hole cut through the hood!!!!!!!!) means that NOTHING that would apply to it in its original condition can now be depended on. I've only very rarely seen anything as butchered as that, that actually worked AT ALL. I wouldn't depend on that to get me to the grocery store down at the corner without killing me by way of a fuel leak catching fire, let alone road-trip in it. One rainstorm would be catastrophic.

Sell it to The Greater Fool. Cut your losses. That thing is too far gone to revive, other than by jacking it up and driving a whole new one in underneath it.

 

Carb bodged onto MPI 3.1 is just too cute and the original throttle body needs to be sealed off all the way so there is no vacume seepage. The two small fans zip-tied to the cross braces are too far from the radiator to cool very well. Looks like O.P. might be over in central Europe, Russia, Ukraine, etc, so lets help him out

 

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