Someone told me that on a big rig truck that a leaky or plugged intercooler could cause an low power and overheating problems. Has anybody had experience with this?

 

Don't know about overheating but it would cause low power.
Should be easy to tell is the cooler is clogged, there would probably be oil in the intake tubes or history of a blown turbo.

 

Yes it will cause low power and heating and lots of smoke(less air)

 

Blown turbo will cause white smoke from oil residue.
Black smoke is fuel that is unburnt.
Look inside an intercooler boot and see if there is oil residue.

Ronnie

 

Meant to post this earlier. We finally got around to changing the thermostat, which is probably one of the first things we should have done. Turns out there was a piece of rubber resembling a broken vacuum cleaner belt wrapped up in the thermostat. I have no idea where this would have come from. After removing this and putting a new thermostat in the truck hasn't overheated once.

 

It's the inner stat seal.
Quite common for the seal to come off and get stuck holding the stat open.
I've found the inner seal to be worthless, the stat and warm up works just the same without it.

 

Mine failed the same way, that inner seal was wedged in the housing.

 

I found my thermostat stuck closed. Out in the country, no replacement, and had to go, so I took the center out of the thermostat and reinstalled. Now, of course it's too cold. It just makes it to the bottom end of normal range.(the mark past 140°)
I'm glad they're easy to get to. 150-160 was easier on the nerves than 210-220. Using a heat gun, I found the stock guage was impressively accurate. It would show around 210 on the gun (pointed directly on the thermostat housing)and the guage. The top hose and radiator would show 160's170's when it was that hot.
I mention this because a "mechanic" told me to point the gun at the radiator where the water entered from the engine to get the temp. That may not be the way to do it afterall.

 

I don't think that was the inner seal, isn't that a thick piece of rubber? It was still intact. This was thin like a vacuum cleaner belt. It was even tapered a little bit thicker on one edge than the other.

 

Water Pump Seal?