My 92 RS gradually overheats after it's run 10 minutes or so. I am out of ideas. I have pressure tested the heads and the gaskets, the fan is running the rightway, and set down low enough to kick on, anti freeze mixture is right,
I have replaced the radiator,water pump, all the hoses, serpentine belt, brand new "16fan, thermostat, antifreeze, and cap. Anything to do with the cooling system is brand new. And it still will run right into the red. I have pressure tested the heads and the gaskets. No luck.
I have read all the posts here I could find on over heating and have already tried and eliminated the possible solutions. Right now I have to run with the heat on full blast to keep it driveable long enough to get where I;m going. This is the only car I've ever seen that will actually over heat while going downthe highway.
Does anyone have any other ideas, no matter how crazy?!?

 

Check your ignition timing. If it's off a fair amount (especially too far after TDC), it can make the engine run too hot.
A cooling problem isn't necessarily the cooling system's fault.

 

i know u said u have read alot on here but i didnt see this mentioned sooo,,, is the air damn in place?

 

For sure timing and the air damn are huge in the cooling of the 3rd gens. But how do you know its actually overheating? Is it getting hot, or is it jsut the gauge. Put a mechanical gauge on it first before you spend anymore money.

 

Oh yeah, it's definitely over heating, checked it with a mechanical gauge. The air dam is in place, but I have not checked the ignition timing. How would I check that?

Thanks for the suggestions. Y'all are great.

 

the only thing not mentioned so far is bleeding the air out. other than that a small crack in the block or head in the right place. when did it start over heating? was there anything that happened just prior to it starting.

 

has the block been cleaned out of any deposits??? i know that can cause some major headaches if the coolant passages are blocked up.

 

no, it's over heated since I got it last year. I have looked every where for bleed valves and can't find them. As soon as I locate one I will give it a try.

 

I did a bit of under-hood work on my 91 RS, and I don't remember having a bleed valve. There definitely wasn't one on the water neck. What you can do, is loosen the upper radiator hose at the inlet neck on the intake manifold (after it cools off). Wiggle the hose back slowly and see if coolant starts to run out. If it does, you don't have an air pocket. Also, after the hose is clamped back on, make sure the radiator is almost full and squeeze that same upper hose as close to the water neck as you can get. Listen for any gurgling, and see if the level goes down in the radiator. Do that a few times, then top off the radiator. You are now officially "burped" the easy way.

 

what type of radiator did you get? i bought a medium quality aluminum radiator from a parts store and it wound up running hotter than the factory brass. the problem was the core was thinner and there were less fins per inch on the capilary tubes. also, how many cfm's is the fan? i have seen 16" fans run from 1200-2450cfm, and a stock 305 with a/c will require around 1800cfm with a decent rad, and more cfm with a lower quality rad. if you dont want to upgrade either of those, you can add an aftermarket add on oil cooler. it screws onto the filter housing, requiring no special tool or adapters. ive heard from some old heads that just a 30-40 degree drop in oil temp resulted in about 10-15 degree cooler engine temp.

a few others things you may want to try is draining and saving the coolant and using a motor flush and water to knock down any scale build up. oil sludge can also cause over heating if the engine wasnt previously maintained.