[TEvans720]

Just rebuilt a 90 302 H.O. it ran great for about 500 miles then she starts to get hot. It running about 230 to 250 degrees. And only at certain times she will run perfect for 50 60 miles then you stop sit inside for a few hours and run to the gas station for smokes and she heats back up to 230.

Its racking my brain cuz we have chages the thermo twice has a new water pump new radiator and full of fluids with good pressure. I don't think it would be a head gasket there is only 750 miles on the gasket.

Any help or comments would be great I may have overlooked and most obvious.

Thanks

 

[85_5.0_HO]

did u allow time to break it in ?

 

[GeorgiaLX]

You could make sure that your fan is working properly, or better yet switch to an electric fan, they always keep you cooler. Also could double check that the radiator cap is good, and make sure that there is no bubbles in radiator.

 

[EagleAutosports]

When you rebuilt the engine, was the block cleaned out at a machine shop? You might have material inside the coolant passages that's affecting the temperature.

 

[50fanatic]

Hows your radiator? Mine was filled with rock-like build-up and I went with a new one. Mine used to do the same thing.

 

[TEvans720]

did u allow time to break it in ?

why would that matter?

The radiator is new the block was cleaned and im getting a new cap tomorrow. So if there is no leak and good pressure it would point stright to a gasket wouldn't it? The fan is belt drivin so that can't be it,

I must have a leak somewhere cuz fluids are disappearing and its not burning fluids. I put cardboard down and letting it sit over night and checking in the morn.

Any other ideas?

 

[50fanatic]

why would that matter?

The radiator is new the block was cleaned and im getting a new cap tomorrow. So if there is no leak and good pressure it would point stright to a gasket wouldn't it? The fan is belt drivin so that can't be it,

I must have a leak somewhere cuz fluids are disappearing and its not burning fluids. I put cardboard down and letting it sit over night and checking in the morn.

Any other ideas?

Your right. The fan is belt driven. But if the fan clutch is not good, it will cause cooling problem, since the fan is not spinning to it's full potential. Check the cardboard, like you've mentioned. I can't think of where else to leak besides the combustion chamber of your engine. But, it's not burning fluid, so it could be leaking outside. Have you filled it more than once after starting the car? When I installed the radiator in my car, after filling all the way to the top, I turned on the car. The fluid went all the way down, below the halfway point, then I went pouring more in, till it stopped going down. That's caused by air in the system.

 

[Blt2Lst]

Are you sure that your gauge is accurate?

My $.02

 

[TEvans720]

The gauge is fine.

The cap was a no go I took one off my truck that I know is good but she still got hot. Could it be putting in a gasket backwards like the intakes or the heads? I thought we put them in right but i don't really remember.

Or I just thought of it we put a bigger cam in it could that be a problem. I wouldn't think so but im not a expert.

Water pump? Its brand new not sure why it wouldn't work. I'm just throwing **** out there cuz it one thing I hate is tearing **** down spending a day and still not fixing it wasting my time.

Its just driving me nuts it worked great for the first 500 miles after rebuild and now the last 300 or so its been doing this ****.

 

[TEvans720]

ok well then I have done everything besides tearing down the motor again and u guys dont have any ideas so it looks like im tearing down the motor again

 

[jeffreyt944]

Jack the car up in the front and then refil the coolant, maybe its air trapped in the block????

 

[88351stang]

I have a couple of questions and some pointers. Is the new radiator larger than the stock one? If it is alot thicker, then you need to trim the fan shroud. To work properly, the fan needs to only sit about half way inside the shroud so it will pull air through the radiator.
Next, as mentioned by 85 5.0 HO, the motor needs to go through a break in, usually by about 2,000 miles. Believe or not, a new motor creates more heat before it is fully broke in.

You mentioned the gaskets on backwards. The intake doesn't matter, but the head gaskets do. If they are on backwards, it will actually trap coolant towards the back of the motor. The coolant will only flow through the front part of the motor. The gaskets will say on them which side is the head side.

See about getting a temp gauge that has the actual numbers on them just to be sure your gauge is working properly. You should be able to pick up one at the local auto parts store for 20 - 30 bucks. Might save you some headaches if yours has gone bad.

If everything else is in the motor is stock, a stock type radiator should be able to keep it cool, but definitely check that fan clutch. In my experience, a good fan clutch always has worked better than an electric fan.

Just my thoughts.

 

[TEvans720]

There is no possible way that a non broke in engine will create that much heat NO WAY. Sure maybe instead of running at 170 she will run at 190 195 no way she will heat up to 250 unless there is a cooling problem. I will say it again the gauge is fine.

I'm losing coolant somewhere I have looked up and down left and right over and over and over again. It is NOT burning it at all. All gaskets are on correctly. So I put a chunk of cardboard under the car check in the morn and there was a half gal on the cardboard. It was right under the bottom radiator hose. Got to looking there was very very small leaking I could hardly notice it. So I tighten the clamp drove her around after filling it back up of course and she was fine. I put the board back just in case and sure enough another half gal leaked.

So I got to thinking when we were doin the rebuild I pulled a staple out of that hose that some retard put in there to hold the clamp there. Not thinking about it I put the hose back on. Now Im sure after the system pressuring up and down for 600 miles has opened that hole up to start leaking a half gal every night.

I'm going to buy a new hose today put it on and do a test run. After this there is nothing left everything is working NEW radiator, water pump gaskets are good pressures good fan clutch good guage good. Well there is one other thing as I said before we put a bigger cam in her which CAN make it heat up more if not timed right. I just can't beleave it would heat up to 250 that way to FU(king hot.

Im doing this all tonight checking the cam degree and the new hose so that should do it there cant be anything else.

 

[wantsum5.0]

try re-torqing the head bolts. after a rebuild you should re- tighten everything from the heads , intake, headers, exhaust,ect. after/before 500 miles. when mine was over heating and losing water,,before rebuild,, it was a head gasket leak going out the exhaust. and if you dont have a over flow bottle, every time you drive it hard :bigthumbsup, you' ll lose alot of water out the over flow tube

 

[87HATCH]

i know this a dumb question but are u sure the water pump back plate is on ? that will give u a problem for sure i have seen it happen , other then that i don't know what to tell you other then try water wetter

 

[87HATCH]

i have also herd that have a thermal stat to low can cause a problem
b/c the coolant will not get a chance to stay cool if under stand what i mean the coolant will get hotter b/c it is all ready in the motor b/4 it hit 180 degrees ... just some food for thougth