2001 Silverado 2500 HD 6.0 gas engine.

For about a year, the engine would overheat on short, or long drives

I noticed the temperature gauge would travel past the 210 degree mark.

Sometimes it would travel past 260 degrees.

As I removed the thermostat, I discovered a substance like sludge

that was in the water pump. I found this sludge in all of the hoses

except the upper radiator hose. I also found this sludge in the expansion tank.

I replaced all hoses, the expansion tank, the water pump with the thermostat.

I flushed the engine, heater core, and the radiator. I also removed the temp sensor

to be sure the channel was not full of sludge.

At this point, the engine doesn’t overheat, the temp gauge travels to

about 180 degrees, and no further.

I haven’t discovered the source of this sludge.

I can say, that this stuff will not stick to a magnet.

This stuff appears, and feels like crushed corn flakes.

 

The sludge is probably from oil getting into your coolant. And I would guess that would be from your head gaskets leaking. I would imagine you have the same problem in the future.

 

If the head gaskets are leaking , I would think that coolant would also get into the oil.
So far, I dont see that happening.

 

Not necessarily. My 2002 silverado with a 5.3 kept getting oil in the coolant. There was no coolant at all that got in the oil. I replaced the radiator and flushed it many times and the issue kept coming back. The only thing that fixed the issue was replacing the Head gasket. That was 2 years ago and haven't has an issue since