wild heat issue

I'm missing something ... so feel free to tell me what else I can check.

I recently rebuilt an 89 cougar with newer parts here and there (kept the rods/pistons/crank, replaced everything else) dropped it back in, had a few problems, but overall she runs ...kiinndddaaa. Not nearly as nice as I'd expect. Anyway.

Start the car up, she runs a little rough (usually requires two starts to get it to idle) but otherwise, no problem. After ... 3 minutes the radiator becomes warm, as in you touch it and "ooo ...ok, no burnie burn yet". Within ... 10 its STUPID hot and this is just at idle.

Sooo confused, I drained the radiator again (FUN!) popped that little bleeder thing next to the thermostat, turned on my heat, full blast and refilled. Ok, great ... not so much, same result.

"It's a blockage" I thinks to meself. Yank the belt off, force some of the fluid out and try to spin it by hand to see if I can get a little fluid to move ... yea, I see a couple little bubbles here and there.

"It's the cap" right? Got to be something stupid at this point ... sooo I start it back up, and watch the fluid come pushing out the top of the radiator. I cap it ... open it again and get more radiator fluid everywhere.

At this point, I'm confused. Usually those tricks fix the problem ... I'm wondering now if its the thermostat or something more insane like its running THAT lean. I'll try to post up a vid of it here in a few minutes for more verification but ANY ideas would be welcome.

Oh, and the fluid is nice and bright green so I'm not getting an oil mix or something stupid like that.

Just a guess, but I have heard of putting the head gaskets on wrong where it blocks a water channel. I hope that isnt your problem.

I have, and distinctly remember the TOP showing up (felpro) and in the front while looking down into the pretty water jackets. It's not a bad guess though and honestly, the time difference between the -rebuilt- and -in the car- was about 4 years. Yea, suck I know.

Oh and most of the other half-~~~ ideas I've come up with usually return me to asking "Sooooo ... how would the radiator get so damn hot then?"

water pump, how's the radiator getting hot?
blockage, how's the radiator getting hot?

See why I'm confused?

Can you get a temperature reading on the radiator? How hot are we talking?

Thermostat stuck open or opening too early? What temp thermostat did you put in?

S_Mazza said:

Can you get a temperature reading on the radiator? How hot are we talking?

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has to be over 150' (can't touch more than 1/2 second) -- this is when its been sitting idle from a dead cold start to ... ~3min

DrFishbone said:

Thermostat stuck open or opening too early? What temp thermostat did you put in?

Click to expand...

would've been a factory thermo, can't remember exactly but I WAS new.

Another fun fact -- if I drive it a long distance (ok, 5 miles) -- when I stop or just slow down the temp skyrockets and the oil pressure jumps

When this happens what is the temp of the lower radiator hose? Is it scolding hot as well? The upper is coming out of the engine. The lower is going in (radiator efficiency). That is how the radiator is getting hot, by the way. You need to know what the temp is going in, on the lower hose, to tell you if your radiator/fan is working correctly. The fan is working, right? Did you reuse the water pump or is it new. And the thermostat? New?

Thank you frdlvr30. That was my next guess. Plugged radiator.

frdlvr30 said:

When this happens what is the temp of the lower radiator hose? Is it scolding hot as well? The upper is coming out of the engine. The lower is going in (radiator efficiency). That is how the radiator is getting hot, by the way. You need to know what the temp is going in, on the lower hose, to tell you if your radiator/fan is working correctly. The fan is working, right? Did you reuse the water pump or is it new. And the thermostat? New?

Click to expand...

water pump was not new but showed no signs of damage or wear.

thermo was new

yes, the fan does come on but no I have not checked the bottom hose ... seems stupid eh? I'll go do that here in a few.

Damn. Top hose is slightly hotter than the lower hose.

anyone got any other ideas/suggestions?

I don't know ... it sounds like the water pump might be passing too little flow. Maybe the pump went bad. Maybe the radiator core is partially plugged. That would allow fluid through, but maybe not enough. Or maybe there is a blockage inside the engine (of course, I understand not wanting to open up a fresh engine.)

Maybe you could splice in some clear plastic pipe to the upper hose temporarily and see how much flow you are getting? I don't know what else to suggest.