Lately I have been having issues with my truck overheating (93' 22re). First I will describe what it does.

The first two times it overheated where on the highway after driving continuously for a few hours. Both times I was able to let it cool down, top it off with coolant, bleed the system and continue on my way with no more problems.

The last time it over heated I was about a block from my house. I had the truck warmed up before I left. Almost as soon I took off the temp gauge went from normal to red very quickly (about as quickly as the gauge can move) and the cooling system boiled over.

Things that have been checked:

No smoke from the tailpipe
No water in the oil
Compression test shows 200-210psi in every cylinder (I have high compression pistons so those numbers are normal)
Thermostat is relatively new, and functions correctly
Cooling system has been bled
Water seems to circulate through the radiator like normal with the cap off

When the engine is at operating temps there seems to be a lot of pressure in the upper radiator hose (I cannot squeeze it by hand). It seems to have more pressure than my other vehicles.

If I let the truck warm up before driving, the idle will increase to nearly 2000 rpms as the truck approaches normal operating temperature. The idle goes back to normal when I begin driving.

I appreciate any ideas for what to check next.

Thanks

 

you got any gunk in your radiator that might be blocking air from going through it? your overflow connected properly? the system will release pressure or extra air through the overflow so make sure thats all good.

 

what temp rating is the thermostat?
how's the lower rad hose? hot to the touch? spongy feeling?
tried flushing the radiator to see if it's clogged at all?

 

I flushed the radiator when I rebuilt my engine about 6 months ago. i don't think that the radiator is clogged. The lower radiator hose is hot to the touch, though, not as hot as the upper hose. I am using the factory 192 degree thermostat (same as I've used since I bought the truck over 6 years ago). Overflow is connected properly.

 

well at least the lower is hot. have you checked the inside of the hose to make sure it's not separated from the outer casing? if that were to happen, the water pump could suck the inside of the hose closed thus cutting off water supply, and it may only happen when the engine's revving up.

with the rad cap off, are you seeing any bubbles? does the water flow increase substantially if you open the throttle up?

have you pulled the stat off and checked it recently?

 

I would buy a new tstat just to rule it out completely. I've had new ones not work before.

If you're sure the radiators not plugged and the t-stat is working, I'd check the waterpump.

 

hows the cooling fan? radiator shroud in good condition. u may have mineral deposits in the radiator restricting flow, if u put tap water in it that may be the culprit.

 

Cheap thermostats don't work for my truck

Last one I bought was a quality one and it works fine

 

22RE's are SUPER suicidal. Have fun with this one. I'd check the fan clutch and replace the water pump. 2 cheap things that could cause overheating.