The compressions do seem to point to an issue. On my D2 I replaced HG’s for coolant in the oil, when the real problem was a bad timing cover gasket. (Just added this for thought).

 

Bought a truck once - owner blew a hose off and overheated it bad. Water in the oil, truck was cheap so I took a chance. Problem was that he blew the front cover gasket due to the overpressure from boiling coolant. Replaced front cover and it ran and drive fine.

 

I was easily able to keep my hand on the metal thermostat housing, so I guess that would indicate the reading was correct. I'll do the compression tests on the right bank, as well, and see if any of my local shops have a coolant pressure tester.

 

@mendenhall2 Auto tool rental places usually have them. When my head gasket went I went from 188 normal running to 196 with a factory grey soft spring thermostat. I had a hairline crack.

 

I was able to complete the compression test of the other bank. The right cylinders were at 135, 125, 135, and 150. So decent. When I take the compression tester back to O'Reilly's, I'll see if they have the coolant pressure tester.

*Edit* I got a coolant pressure tester from Advance, but it's not doing me much good with the cracks in my expansion tank... We're on hold for now.

 

Picking this back up, I was able to complete the coolant pressure test after replacing a few components that were letting pressure escape. I pumped the system up to 20psi, and it slowly leaked down to 15psi over about half an hour. Then, it held at 15psi for three hours before I shut every down for the night. What does this tell us? I believe I read in the RAVE that the coolant system is rated for 20psi. Would it have leaked down to zero if the head gasket was actually bad?

 

The pressure relief valve is set to 1.4 bar (stamped on the reservoir cap). 1.4 bar = 20.3 psi. Everything should be tight at that pressure. Maybe the hoses are expanding slowly and the compressed air cools down that causing the pressure drop?

 

Test again the morning and let it hold all day. It should hold pressure all day, if it does not you have a leak. Likely HG given the 115ps on one cyl, which one was it? if it is an end cyl that is most likely the problem.

 

The low cylinder was #5, so not an end one. I pumped the system up to 20psi this morning, and got a very different result. It's cold here - for Florida - at 35F, and I immediately heard hissing from two spots. The pressure was dropping fast. The hose at the cold side of the radiator was bubbling something fierce, so I tightened that clamp and stopped it. But there was also a decent amount of coolant leaking from under hard hose just before the thermostat housing. The RAVE's coolant path diagram is a little confusing to me. Does that come straight from the water pump? Is my water pump gasket leaking? I still haven't drained the coolant and inspected the impeller, since we seemed to be moving away from the water pump being bad.

*Edit* The gasket may have just needed to get wet. I went back out a couple of hours later, and it's holding at 15psi again. I pumped it back up to 20 and there's no hissing. So I'll check again tonight and see if it holds.

 

Metal pipe is coming out of the intake manifold. Seal the leaks and test, if it will hold for 6-8 hrs without dropping pressure you do not have a leaking HG. Suggest you run cap one full turn loose going forward. Explanation here: https://landroverforums.com/forum/di...46/#post887409