Why am I overheating?

[DannyBoy515]

I understand all of you guys are correct. But before we have the guy pulling his engine or throwing a rock through his engine builders window, lets see if it is an overheating problem and not an engine problem first. I would guess just because the engine is newer doesnt mean the remaining parts under the hood are also.

First off, be sure whether it is a cooling system/overheating issue or an engine issue.

Are you using a fan shroud?
Are you sure the the thermostat was installed correctly - not upside down? (Hey it happens)
What type of cooling fan and water pump are you running? If it is a stock fan, you have to be sure the fan clutch is kicking in and the fan is cooling the radiator.


Check the basics first - open the radiator cap and let it get up to temp - be sure the water pump is circulating the coolant - if it is basically full you will be able to tell if there is circulation at the top of the radiator.

If all of these things check out (which I have a feeling something wont) - Before I went into the motor, I would take the half an hour and the 10 bucks and install a 160 deg thermostat and see if that solves your problem. More than likely there is something causing the overheating that is just being missed. If you, or a knowledgeable person goes through the other options and come up with nothing, then pressure test the cooling system and see if there is an issue deeper within. Then it would be time to start getting upset with the person who built the engine. But there are alot of issues that could be the root cause that are alot simpler to check before tearing into the motor.

 

[86 Grand prix]

I just had a similar problem on my new install. I had a brand new engine, transmission and all new radiator. It went past 230 or so three times on start up in just a few minutes. I took out the t-stat and tested it in a pot of water using a digital meat thermometer. It worked perfect. I re-installed it and filled with antifreeze mix again and it still ran hot. I think I finally figured out the heads were air locked. I took off the cap and kept pumping the top hose by squeezing it and a huge amount of air came out of the radiator and I was able to get almost another gallon in. Now it runs at 180-190.

 

[hereiam]

You can get a little test kit (most automotive stores carry it) that you put where your rad cap goes. You add a blue liquid into the holder and and it usually will tell you if you have a head gasket leak. The blue liquid will turn yellow. From what you have said, I personally dont think you have a head gasket leak. I think that you probably have an air lock in the system. Sometimes it is in the heater core and other times it is in the water chambers. Now something else you may want to check is that if the fan is a thermostatic fan then it may not be locking up when it warms up. It may only be turning with the friction on the shaft and not giving full cooling. Just a couple of thoughts from miles away

 

[Brownianl]

Sounds like air in the system. Remove your thermostat housing, fill the block through the thermostat housing, reinstall your thermostat, housing and upper radiator hose, crank it with the cap off and top it off gradually when your thermostat opens.