Subject: [Mgs] Oil Gallery Plug Leak

From: Stan Fickes via Mgs <[email-masked]>
Date: Thu, 13 Sep 2018 14:25:30 -0400

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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.
Thanks!
Stan

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<div dir=3D"ltr">I&#39;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 wit=
h 1/4&quot; NPT steel plugs. I tapped the bores, like I see advice for in m=
any places, and installed the plugs. (I have since seen that the .505&quot;=
 bore is too large for the tapping operation, which should have started at =
7/16&quot;, so that probably explains the leak.) I used Permatex Ultra Blac=
k on the plugs. Months later (did I say it seemed never-ending?) I installe=
d 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 pudd=
le of oil under the front crossmember. I pulled the motor back out and foun=
d the right-front plug was leaking. I removed the plug, then tried again us=
ing Avation Form-a-Gasket. No change to the leak. Tried it (from advice) wi=
th Permatex Thread Sealant with PTFE. The leak is slower, but still a probl=
em. 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 e=
lse to try first? I have cut away the front plate to allow plug removal wit=
hout disassembly, and am using a pre-oiler to pressurize the system so I do=
n&#39;t need to R/R the motor with each attempt. It&#39;s out on a stand no=
w, and will be until the leak is gone.<div>Thanks!</div><div>Stan</div></di=
v>

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