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Leakdown test good/running bad

Posted: 07:38 pm Sep 24 2023
by JZ05220r
I pulled my 220 engine out today because of the headgasket issues and the excessive smoking issues I wasn’t able to resolve. I decided to pressure test it and after 20 minutes at 5 psi I only lost 1/2 psi.
    That’s pretty good from what I have read but it actually makes me uncomfortable because of the issues that I was still having.
      I still don’t know how I am going to be able to get the dang headgasket to seal after trying resurfacing the head and wasting a bunch of head gaskets trying to get it to seal. The cylinder was resurfaced prior to these issues. I recently confirmed the leak with the mityvac cooling system pressure tester while running and with the engine off.
        I don’t believe a bad water pump seal, or leaking radiator hoses/connections would bring any bubbles in the cooling system.
          My “master” plan is to try to get my hands on a fresh 200 cylinder and have the cases split, crank balanced. I’d even throw on a new airstriker for the hell of it.

          Re: Leakdown test good/running bad

          Posted: 12:39 pm Nov 09 2023
          by Chuck78
          I'm still baffled as to all the difficulty you had getting your head gasket to seal. Were you using OEM head gaskets? The only thing I can think is that perhaps your head still was not flat enough. Are you using the proper torque sequence? What grit did you use to finish the head gasket surface? And did you do the same for the cylinder or was that professionally done? Was that double checked? I would put a machinist's straight edge across the cylinder particularly around these studs, and make sure it is not raised anywhere. Are you using proper torquing sequence when installing? Was this installed dry, or did you use copper coat head gasket sealant or similar?

          At any rate, the 200 cylinder should get you back in the running. I wonder if the head was just milled too thin or if something was wrong with the casting? Had you tried multiple heads?

          Re: Leakdown test good/running bad

          Posted: 01:20 pm Nov 10 2023
          by JZ05220r
          Chuck78 wrote: 12:39 pm Nov 09 2023 I'm still baffled as to all the difficulty you had getting your head gasket to seal. Were you using OEM head gaskets? The only thing I can think is that perhaps your head still was not flat enough. Are you using the proper torque sequence? What grit did you use to finish the head gasket surface? And did you do the same for the cylinder or was that professionally done? Was that double checked? I would put a machinist's straight edge across the cylinder particularly around these studs, and make sure it is not raised anywhere. Are you using proper torquing sequence when installing? Was this installed dry, or did you use copper coat head gasket sealant or similar?

          At any rate, the 200 cylinder should get you back in the running. I wonder if the head was just milled too thin or if something was wrong with the casting? Had you tried multiple heads?
          Yea that was a pain in the butt. I noticed it after the winter (during winter I took the head off to check things). Then I went through 4 head gaskets, 3 of them were moose racing brand and one head oem head gasket. I lapped the rb head and the stock 220 head and it got better but never sealed up completely. I then moved on to another cylinder as the porting wasn’t working well on my cylinder. Same issues followed. Weird.