4.0 - replaced entire cooling system, still overheating

Unclewolverine said:

If only some had said earlier that your not very old radiator had likely gotten blocked because scale had been broken loose from flushing it...

Click to expand...

I read the entire 29 page radiator thread (awesome thread BTW) and I agree that was most likely the problem. It's weird how many people eventually ditched their Mishimotos due to frequent blockages.

I wanted to give an unexpected update. After the aluminum radiator, my cooling situation dramatically improved and rarely went past vertical in any condition.

So, on to the next project. I had an annoying leak on the crank seal in the front cover, so I went ahead and got a timing chain set and harmonic balancer and installed those over the weekend, and in addition to no more oil leak, the cooling also definitely improved. The factory gauge did not hit vertical (210) at any time on the freeway or Whataburger drive through.

2001 XJ with 198K and there was quite a bit of slack in the chain. FSM says to replace with 1/2" inch or more of deflection and I definitely had at least that much.

I wish I would have replaced the timing chain while I was doing the water pump.

Well news update - finally gave up and took it to the shop. They told me my brand-new NAPA fan clutch was bad! Problem solved. No telling how long it would have taken me to figure THAT one out........just glad it's running well now! Sure appreciate all the great help here.

Amazing it came down to that.