I have an 86 camaro I-rocz it has a 355 in it. I did a rebuild recently on it and every since the rebuild it over heats unless i keep it in 5th gear on the highway, any other gear it overheats fast, so going through towns and stopping at stop lights makes it jump way up. It does have a carb, when i did the rebuild i replaced the water pump, radiator with a bigger one all aluminum dual fan set up, 50/50 antifreeze, at this point im at a loss as to why it would be over heating, also the airdam is fine. Any suggestions would be greatly appreciated. Also tried replacing thermostat with another 185, tried 160, tried no thermo, all the same. Oh and the hose is not collapsing on the radiator either already replaced that.

 

Did you get the right water pump? I've read some threads about reverse flow water pumps. Also, how's your gauge/temperature sending unit? Did you replace the sending unit? Do you know how accurate it is? Mine is off by quite a bit: reads 220 and not even above 200. For what it's worth, these run hotter than you might expect. Forgive me here, as I don't know your experience. Do you notice any coolant boiling in the overflow, or gurgling in the block after you shut it off?

 

Oh yes the coolant was boiling bad. and I hope that its not a reversed water pump, I got one from autozone that was supposed to be factory. no I havent replaced the sending unit, but with the coolant boiling im sure its right on lol

 

Did you have dual fans to start off with? Or did you swap them over? The only thing I'm getting at here is to make sure they are rotating the correct direction, i.e. pulling not pushing. Maybe replace the radiator cap too? I'm sure you did that when you put in that new rad. If you did swap in those two fans: are they universal or specific to third gens? What's the cfm rating if so? And yeah, if it's boiling, there's not much need for worrying about that temp sending unit or the gauge, even if it is off

 

It is a dual fan setup now, and they are going the right direction (there was no other way to mount them lol) Can a radiator cap make that big of a difference? it came with a new one BUT it was bent so i used the old one which is factory. I dont remember what the CMF rating is right off hand, but supposedly the radiator/fan combos were garenteed to cool up like 750 - 800HP engines, and i know mines nowhere close to that

 

If your radiator cap is bad, you would lose the ability to hold pressure in the system. That can cause overheating for sure. Replace that and see if it solves your issue.

 

He's referring to clockwise or counterclockwise, not front or back of the rad.

 

I know which he is referring to. its pulling the air through the radiator just like the original. And thank you I will give it a shot. That cap sat outside in the elements for over a year so maybe thats exactly what it is. Thank you very much I will give y'all an update tomorrow

 

Sounds like you're not holding pressure. It could easily be the cap.

 

Can the cap be messed up and not holding pressure while not leaking any fluid? I've just been working on this car for so long and im ready to be able to just take it out and have some fun

 

A failed cap will allow coolant to boil over into the overflow reservoir far below its rated pressure. Without building pressure the coolant will boil far below the system's maximum temperature.

A motor that is not properly tuned will also burn more fuel for an equivalent amount of work compared to an efficiently tuned motor. The fuel that is not converted into work is wasted as heat.

 

Thank you all very much, I was at a loss. Now to just get off of work so I can go test this out. If it does it will be time to break out the home made saki and relax happily for a while

 

Ok new cap wasn't it now i am really at a loss here. On highway it gets to 210, in town it got up to 230-235. Any other ideas?

 

If it cools fine at speed but not at idle, it's an airflow issue. Verify your fan is working properly.

 

When driving at speed, does the coolant temp drop back down to the 210 mark? Or does it just get hotter the more you drive it? I would look into just draining everything, refilling it and going from there. If your flow is the right direction, it has to be air flow. Also, what is controlling the fans to come on? I know that won't matter over 40 mph, since the fans should shut off after that but it's just a thought. It has to be coolant flow or air flow, so try looking into the components you changed for your problem.

 

In 5th gear at 60+mph yes it does cool back down to 210. And i have to fans wired that they are always on.

 

I really think this is more of a coolant flow issue. With speed above 60 mph, it should really be cooler than that. It sounds like you aren't getting good flow through the engine. What that could be though, I don't really know. It more than likely has something to do with the parts replaced during the rebuild. Check on the flow direction of that pump, and look up the proper flow direction for your year camaro. If someone else on here knows more about the reverse flow pumps, or if this could even be his issue, jump in here and let us know. JMO, but I'd focus on the coolant system from here

 

I just popped off the top hose on the radiator with it running and it is shooting the coolant out there really doesn't seem to be any blockage.

 

Could it just easily be an octane issue, the engine is easily 450+ HP

 

It doesn't have to have a lot of flow to have pressure, which can give you that coolant shooting out from the top hose. I don't know what else to tell you here, as everything beyond this point will most likely have to do with the issue arising from the rebuild.

 

I hadn't thought of that. Was the coolant still boiling over after you changed the rad. cap? 235 really isn't overheating, and if your gauge is like most of ours, it reads high anyway...

 

Unless you are running lean, I wouldn't imagine it would be an octane issue. But I'm not experienced with using or needing to used different types of fuels. As long as your compression ratio is normal, I wouldn't imagine that's what it is. But, like I said, I'm no expert.

 

Actually it was not boiling, so you think it could just be reading high, and for that old of an engine 235 isnt high?

 

If it wasn't boiling, I'd say replacing the radiator cap fixed your issue. My temp gauge reads 220 with temp less than 200 even after I replaced the temp sending unit. If your car came with dual fans originally, the ECM wouldn't turn on the 2nd fan until like 230 or something. That's just what GM did then. If it's not boiling, you should be ok, but keep an eye on it. Or, better yet, buy yourself another radiator cap with a thermometer in it to tell you actual coolant temp. I probably should have given that advice first....my bad

 

Well i just let it run for about 10 minutes, the temp at the gauge was reading 245 it wasnt boiling back but i shut the car off and decided to loosen the hose a bit to check, lots of pressure and air seemed to come out, and there was a tiny bit of coolant that came out with that and when it hit the outside of the radiator it was evaporating it and smoking but the smoke was not coming from inside the hose.

 

I let it idle for 10 minutes rather, and the hood of the car was to hot to lift i had to get a towel. it almost felt like i was touching the engine itself. and it didnt come with dual fans originally, it was the single fan. and i have the fans wired to come on as soon as i turn the key.

 

That air could be steam from water boiling off. I know you put dual fans on it, I'm just saying they were designed to come on hot. You may just have too much power for the stock flow designs of the water pump. Was the radiator a stock replacement, or an upgraded one? You may have to find a higher flow water pump to keep up with the power increase

 

No radiator is an upgrade, now i have thought about that, needing a high volume water pump, thought about going to an electric water pump.

 

I hear good things about the electrics, but haven't used one myself

 

Don't install an electric pump.

If your car came with the serpentine belt system it should have a reverse rotation pump. As long as you haven't changed the acc drive system the water pump for that year model is correct.

Octane won't change temperature.

Acquire an infrared thermometer and see what the coolant temperature actually IS by reading it from the water neck.

If it's not boiling over, it isn't overheating.

You should be able to see coolant flowing through the radiator as the stat opens by peering into the rad cap opening. Do not open this when the motor is hot.

 

You have the wrong water pump dude. You have the standard rotation not the reverse for the serpentine belt setup. Pull it and take it back. Tell them they gave you the wrong pump and if they try to tell you it is the same throw a fit. Probably need a new thermostat too, high temps will cook it. I have the same setup 355 with dual electrics that run all the time and mine gets nowhere near that hot. I will add that I live in South Texas.

 

Well i just let it run until the temp leveled out, it hit 250 and then dropped to 245, no coolant spewing no boiling im assuming the gauge is just really far off and how would i know its the wrong pump? its going the right direction, plenty of flow

 

and i need the reverse? why do i need the reverse rotation?

 

86 should have v-belt setup and use standard rotation water pump. You can verify the correct water pump by observing the flow as I stated above.

The temp guages are notorious for being off. Do not assume they are any indication of the actual state of nature at the end of the sensor.

 

Its not a stock engine, I have no tensioner pulleys or idler pulleys, Just the alternator which is on the passenger side, the water pump and the crank, it spins the water pump clockwise. Which thats the pump I have on it, or so autozone tells me. and its a standard belt, not a v belt, now i do have a v belt that goes to the power steering only.

 

The guy i talked to thinks I may have a blown headgasket if it is over heating, I may run and get one of the radiator caps like was suggested to see the actual coolant temp

 

which belt do you have?

 

Both, the bottom one goes around the crank, alternator, and waterpump, top goes around crank and power steering

 

Is the ribbed side of the belt turning the pump or is the smooth side turning the pump? If it's the smooth side you need a reverse flow pump, if it's the ribbed you need a standard.

 

How about a picture. I don't think I've ever seen both a serpentine belt and a V-belt used at the same time.

 

He probably has something like this going on with his crank pulley. This is a water pump pulley off my '72 camaro block.

 

Difference in diameter?

 

Yes thats what the pulley looks like, before the rebuild it didnt over heat with that, but im assuming now its a blown headgasket, im going to buy the compression leak test kit when I get off of work to test it. Also I will post pictures when i get home

 

Here are the pictures, ok there seems to be an excsive amount of pressure, i drained some of the coolant as you are supposed to do with the compression leak test (the one with the fluid) and it builds up so much pressure no matter what that coolant comes out, i jumped back after moving the tester off and it had fluid running out, i shut the car off and it sent about a 4 foot stream of coolant out the top of the radiator.

 

So after noticing that i am more leaning back to its the wrong pump again. I think i need a reverse but my knowledge is limited.

 

Your 86 uses a standard rotation pump. It has a v-belt accessory drive. Do not be confused by the width of the belt that runs the alternator.

Have you even determined that it is overheating yet?

 

It is over heating, the gauge is almost dead on

 

Is it normal for it to shoot coolant like that?

 

your waterpump is the correct one for your mid-85 through 87 style pulleys-'88 up is the reverse rotation.

 

A "compression leak down test " is done through the spark plug holes with the plugs removed. The device has a long piece of hose that screws into the hole, & has 2 gauges connected to it. 1 gauge will show current compression & the other will show how much pressure has " leaked down ". This is done on each cylinder.
Is this what you did or did you do a " cooling system pressure test " ?
( edit )
The cooling system test should NOT be pumped up more than your radio cap pressure.
The device should also have a fitting & instructions to test the radio cap.