M60b40 headgasket????

[WYZEUP]

I've been trying to diagnose a bad running motor for the last month with changing all the sensors, checking for vacuum leaks, another ecu....pretty much covered all basis.

Today while running the motor I notice a small coolant leak from the temp sensor, under load it gets worse and then also noticed it pushing fluid out of the end tank of the radiator...
While at idle it doesn't do it but with load on the engine it starts, haven't done compression or pk test yet, they are next on the cards but this is leaning me towards headgasket??? Assuming it's cracked between cylinder and water gallery?

[wworm]

do your tests. Too many factors at play to be sure without doing a compression or leak down test first.

[st.petebiodiesel]

I had a M60B40 in a e30 with a similar issue. If you beat on it hard it would pressurize the cooling system and puke coolant out of the reservoir, and overheat. Drive it normal for 5 minutes and the temp would come back down and the engine behaved normally.
Leak down test was perfect about 160 on all 8. I even rented the tester for combustion gasses in the coolant and it passed, but I couldn’t recreate the engine under heavy load while performing that test.
I figured it was either a blown head gasket or a crack in the head or block.
Engine still ran great but if you made some pulls to redline it would peg out the temp gauge real quick.


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[The Dark Side of Will]

Put pressurized air into each cylinder sequentially and see if you get bubbles out of the cooling system.

[Andre3127]

Put pressurized air into each cylinder sequentially and see if you get bubbles out of the cooling system.

My thoughts are that air from a compressor wont have enough pressure to find all head gasket leaks unless they're big. 120 psi from a compressor is nowhere near the 1000-1500 psi figures that I've seen online from a quick search.

[The Dark Side of Will]

Never fails me. I had a similar situation, in which the engine ran fine at low/medium throttle but would immediately overheat after one run at WOT. #4 blew bubbles out the fill cap.