I have the inline t stat mod.

 

I hate to say it but if you aren't seeing puddles after parking then it's probably a HG job in your future.

 

This spring I had an internal coolant leak, which I incorrectly diagnosed as HG's. I should have investigated further, but I removed the heads before I figured out that wasn't the issue. A pressure test would have helped me diagnose it. Obviously I now had to replace the HG's. The real issue was a bad gasket under the timing cover which allowed the coolant pump to pump coolant directly into the chain area, and down into the sump. After replacing it i have been driving it now for several months with no leaks. One tell tale sign I should have clued into was the grey sludge on the oil filler cap.
2001 D2 4.0

 

The real mystery here is that the coolant goes down in the ET, then returns. There are no puddles, milky oil, white smoke...nothing.
I plan on pressure testing it this weekend.
When I do, what’s the procedure for the overflow tube. That’s gotta be out of the equation for pressure testing, right?

 

What would happen if the small 5/16" hose from the top of the Rad to the ET was plugged?

 

how did you fill it through the bleed screw if you have the inline mod? Doesn't that eliminate the T and the bleeder screw.

 

@Dave03S Normally yes but there mods that add an inline bleed point

 

 

Park it on a hill!

 

My apologies for the delay on getting back on this thread. Life’s been a real 2020 lately.
This problem seems to just more and more weird. I did the pressure test. Pressure held solid for an hour. The engine temps are still erratic which, as previously mentioned, would indicate trapped air. I have bled the system repeatedly. On a hill, on ramps, expansion tank lifted...all the things. Anyone have any suggestions before I take it to the shop?