Replaced headgasket, now all valves leak

nidddq
Sat, 27 Jul 2024 05:15:14 +0000
Maintenance/Repairs

I bent two valves on my 6g72 it’s a fwd dohc v6, I replaced all 4 valves for that cylinder , it’s cylinder 3 in question. I got 180 psi all around but cylinder 3 was still low but better at 80 psi. I did a leak down test and cylinder 3 failed as expected but all 5 other cylinders got within 5% leak down. I pulled the head back off and did the old compressed air and water trick, found out one of the exhaust valves I didn’t seat properly, i redid the seating process until there were no bubbles doing that test. I threw head back on and now all the cylinders are leaking on that bank. So I changed the headgasket and used copper spray, same thing… inspected the head for cracks, got it resurfaced, same thing. I took the cams off so that there’s no tension on the valves, same thing…. Cylinder 1 is leaking into cylinder 5 and cylinder 3 into cylinder 1, cylinder 5 into cylinder 3. No leaks in the cooling system or crankcase, it’s leaking out the valves some how. Anyone know what could’ve happened? I’m thinking i will need a new block/complete engine.

11 posts - 7 participants