Hey guys I'm hoping one of you can help me out with my problem I'm having on my 91 Camaro.. My car keeps running hot and the coolant boils on me.. I put in a rebuilt 350 bored over, 3 row aluminum radiator,& cap, new air dam, new hoses, new thermostat, new head gaskets, new water pump, smog pump, new coolant reservoir jug, rebuilt 700r4, new cat Conv, new flow master, new piping, the single fan is wired to run when the car is on, and the car keeps running hot.. It's super frustrating.. I am starting to think maybe my engine is just not rebuilt right.. I love the car and I do not want to let it go but I am not rich..

Does anyone have any suggestions? Thanks for reading..

 

what size thermostat? (rare but these can be faulty too)
check engine oil to rule out head gasket (i know its rebuilt but anything can happen)

if u can get an IR scanner find out how hot shes getting..

silly question but..check your oil levels.?

gotta start some where..

 

It's a 180 thermostat and The oil was just recently changed.. The gauge hits the red mark..

It's 5.7 TBI.. Do these cars have an intake manifold on them? If so I haven't changed that..

 

Did you burp the system after putting all your new coolant in it?

Get an IR gun, see what the temp is actually at on the water neck compared to what the gauge says it is.

Does it overheat on the highway as well as the in traffic/low speeds? if it does, then you got some serious issues going on.

Also, who tuned it once you put it all back together? If it's running lean it'll run hot.

 

where is the timing set at?

 

The 3 core radiator should keep you cool. You said you have the air dam in place, but is all the nose radiator shrouding in place too? It was meant to direct airflow through the radiator.

 

which way is the fan spinning?it should be pulling air towards the motor from the rad

 

When you put the 350 in did you also put in larger injectors and bump the fuel pressure so you wont run lean?

 

It might be the water pump. It could have a pin hole leak under pressure, check your coolant levels to see if you are loosing any. New thermostat can be defective as can pressure cap .

 

Like Ozz asked when does it overheat? If at all times and pretty much whether driving or idling there is something really wrong. It sounds like you have all the "right" pieces as far as thermostat, radiator etc. There are some differences though between our cars and earlier sbc such as reverse water pump rotation. Make sure your pump matches the accessory drive. Make sure the tstat is opening and you actually have water flow through the radiator. Also, the heater hose routing is a little different than before. Some of the water can bypass the radiator if it's not set up properly. Then start looking at other things like timing, fuel supply and air flow through the radiator.

My car did ok on the road but would get pretty hot in traffic and part of the fix was a larger under radiator dam. I fabricated one from some conveyor belt. Come to find out the nose of these cars can "sag" over time leaving the ground effect basically blocking air flow to the radiator dam. But things like that will only contribute to a overheating issue, not make it boil over on the road.

 

Try running it without the Thermostat still glue a new gasket on it but remove the thermostat and let the car just sit And run or drive close in your area to see do Get hot. New thermostats can be bad too. If it runs good without the thermostat and do not get hot ask your mechanic is it okay to keep it like that just to be sure.
I am NOT a mechanic I just had a lot of caRs with a lot of problems before and that is one thing that I tried. Oh yeah change both your radiator hoses I had a car run hot the hoses look good but when the car heated up the hose opened up and let the fluid out I did not see it while I was driving it look like a little flap when they close you could not see . Like the other member said it could be your water pump - that's bad they do not always leak when there's a problem

 

The car usually starts making a growling noise from the reservoir and runs hot when I'm in traffic.. I got the timing set, fuel pump replaced, but still running hot.. I can see the water flowing good through the radiator.. The fan is blowing air toward the motor.. It doesn't feel that strong tho I will replaced the motor on it.. I will change the water pump it's been a couple years since I swapped that..

I haven't changed the spark plugs I will try that as well.. Thanks for all the help guys.. I love this car and want to enjoy it already..

 

What if you drive with your heat on HIGH! Turn it all the way up and the fan on high. Does that change anything?

 

It actually does.. I can see the temp start dropping when I have the heat on high.. Why would that be?

 

The heater uses hot engine coolant. When you crank up the heater, it draws heat from the coolant to heat air in the cabin.

 

I forgot to tell you Check your catalytic converter if it is red hot that is bad. The catalytic converter cause your car to not breathe right lose power and it'll make your motor hot too if its not working right.Some people can hit the catalytic converter to see if its bad but you want to try it at night if this like to see a bright red that mean is bad and it will cause your car to run hot too

 

That's actually a good idea if nothing else is found. I'm not a big fan of going without a tstat but it would at least eliminate a variable.

Yes, the heater does act as auxiliary cooling, sort of a small extra radiator. Well that's exactly what it is. If something like that is helping you may not be too far off.

But to troubleshooting, does it keep a stable temp when driving steady at 50-60mPH? If so your fans may be an issue. I swapped over to the 4th gen setup. It is basically the same fans but in a shroud for better air control. If it gets hot driving down the road I suspect you have a water circulation issue of some sort.

One other crazy thing to check is make sure a plastic bag or big piece of trash isn't blocking the front side of the radiator.

If everything in the cooling system is good, timing set, fans working etc the only other things that I can think of is head gasket, cracked block or heads or possibly something in the reciprocating assembly. But double check everything else first.

 

What kind of fan (s ) ( CFM) you have on? Single, dual ?. I went thru it with a 1989 Camaro Iroc, 5.7. I found out that overheating sometimes is caused by one part or one adjustment but it could be a group of little different things. Timing affects the cooling system, a bad air dam deflector, a bad pump,radiator etc, but in my case I found that air in these vehicles is the most affecting item of all when it comes to overheating. I did replace my rad with a three row Champion with shroud and fans ( fans advertised at a total of 2800 CFM) not true. Ended up replacing with other two fans from Ebay ( advertised at 4000 CFM) not true. In reality the only solution was buying Mishimoto fans at a real total 3600 CFM that did the trick, plenty of air coming thru. I also replace the fan sensor for 180 degree instead of the 195 factory for earlier start up.
When it comes to CFM advertising BEWARE

 

I agree. My experience is often a few different issues have to be addressed to get consistent results.

Also on the air flow issue. My car does great with the stock radiator as long as I am moving. I don't really think it is a water flow issue. The stock fans are barely adequate for stock. I went to the 4th gen setup and although it is better, the air flow is lacking still. I think part of it is the nose/engine compartment design. Air cant get out and with the bottom feed we get a lot of "short circuit" in the hot radiator air gets back under the rad and comes back in the front. When moving the dam helps prevent this problem.

I noticed the other day in a parking lot was a suburban type truck idling and the fan/s sounded like some sort of industrial vacuum cleaner. I thought man I need one of those fans! Air flow ratings are suspect as you have noted. Even if they are accurate I think our cars pose more of a restriction so the fan needs to be able to move X air at Y pressure drop. What we really need is the ratings to show a curve across different amounts of restriction. In leu of that it really is a trial and error selection process and relying on other's experience. Tell us more about the Mishimoto fan you found. Is it aftermarket or OEM?

 

my 07 tahoe sounds like that when i put the ac on lol