[TR] Leaking rear seal on my TR3A's engine

[Gerald Van Vlack]

I'm following this rear seal thread and need to comment.  The newest seal design works well with a few items that need followed in conjunction with it's install.


  1.
Be certain that the flywheel bolts do not cut into the installed seal. If using the ARP bolts they need to be shortened a small amount by grinding the ends slightly. I don't know if the stock bolts need the same modification but worth inspecting to be sure.
  2.
The best seal will be blamed for a leak when in fact it's not the source of the leak. When installing the rear main bearing cap very careful attention needs to be paid to sealing the cap to the block. That large rectangular slot that requires a rope seal pounded into it if not sealed well enough will leak and frequently is the source of oil being seen dripping from the hole in the bellhousing. And then folks blame the rear main seal when in fact it's that interface between the block and cap that is the source of the leak.

My comment is don't blame the crank seal in many cases.

JVV

________________________________
From: Triumphs <triumphs-bounces at autox.team.net> on behalf of Dave MacKay <dave at mdmackay.ca>
Sent: Wednesday, February 12, 2025 10:39 AM
To: triumphs at autox.team.net <triumphs at autox.team.net>
Subject: [TR] Leaking rear seal on my TR3A's engine

I followed the recent exchange about “TR Rear Crank Seal Rope?” with
interest and corresponded with all who replied to the OP. That has me
thinking about how I might address my situation.

In 2008, the engine in my TR3A was rebuilt. As part of that effort an OIL
SEAL CONVERSION KIT was fitted. The conversion required that the scroll on
the crankshaft be ground down. It has always leaked.

I had convinced myself that fixing the leak would be too much trouble and
too expensive to be worth doing. I envisioned having to replace the
crankshaft and then using a more modern conversion (Moss 837-160). I
wanted to check with the list to see if that’s the case or not.

I believe --- but am not certain --- that the conversion was sourced from
Moss (perhaps p/n 837-006). I am aware that incorrect instructions were
provided with some of the conversion kits so that the crankshafts were
ground too small. I don’t know if that’s the case with my conversion: the
crank may have been ground to the correct dimensions, or it might not have
been.

I have three questions:

1) Is there a way to check the crankshaft dimensions to see what it has
been ground to that doesn’t require pulling the engine? I’d like to know
if the crank had to ground to the correct dimensions or not.

2) If the crankshaft was ground to the wrong dimensions, is there a way to
fix it (e.g., special seal) short of replacing the crankshaft? Replacement
crankshafts are scarce and quite expensive (>USD$1600).

3) If the crankshaft was ground to the correct dimensions, what have
others done to keep that oil seal conversion from leaking?

I’d welcome any input from those on this list.

Dave MacKay
1960 Triumph TR3A, s/n 68639L
near Toronto, Canada
** triumphs at autox.team.net **

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