[Mgs] Oil Gallery Plug Leak

Stan Fickes spridget at gmail.com
Thu Sep 13 12:25:30 MDT 2018

I'm finishing the seemingly unending rebuild of an MGA 1600 motor, and am
stuck with a leak. When I had a failure of a brass plug, I chose to replace
the big plugs at the end of the long oil galleries with 1/4" NPT steel
plugs. I tapped the bores, like I see advice for in many places, and
installed the plugs. (I have since seen that the .505" bore is too large
for the tapping operation, which should have started at 7/16", so that
probably explains the leak.) I used Permatex Ultra Black on the plugs.
Months later (did I say it seemed never-ending?) I installed the motor into
the car and fired it up for the 20-minute cam installation run. It looked
good at first, but after 20 minutes I have a foot-wide puddle of oil under
the front crossmember. I pulled the motor back out and found the
right-front plug was leaking. I removed the plug, then tried again using
Avation Form-a-Gasket. No change to the leak. Tried it (from advice) with
Permatex Thread Sealant with PTFE. The leak is slower, but still a problem.
I am about to JB Weld the plug into place, but have concerns about its
permanence. Will I be able to remove the plug at next rebuild, or at least
have a machine shop do it without machining the block? Is there something
else to try first? I have cut away the front plate to allow plug removal
without disassembly, and am using a pre-oiler to pressurize the system so I
don't need to R/R the motor with each attempt. It's out on a stand now, and
will be until the leak is gone.
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