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

[Frank Fisher]

 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.
you would have to pull the oil pan off and remove the rear main cap and then you could get a measurement.
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).
nope. if its undersize your done.
3) If the crankshaft was ground to the correct dimensions, what have
others done to keep that oil seal conversion from leaking?

i have done 2 that required the crank be machined.i found in both cases that i needed to shim something. the new scroll seal was interfering with the flywheel. im thinking i had to shim the flywheel with a single washer. just be sure you check that things turn ok with the transmission mounted before you put it in the car. yes i put it in the car the first time without checking.its been more that 10 years since i did those builds so forgive the memory.the other thing i did when assembling the scroll and seal was:1) make sure the scroll and rubber seal are very clean by wiping with alcohol or similar.2) then i wiped the crankshaft at the point of touching the seal with oil on my fingers. just enough to leave a thin film. 3) where the rubber seal comes together i applied some RTV silicone adhesive to the joint. its ok if it oozes a little as the oil on the crank will not allow it to stick to the crank.4) once assembled let it sit for about a week to let the sealant fully cure. do not turn the crank, do not move any parts.having done this method twice i have had what id like to say is no leak, but a small stain occasionally has been experienced.

Frank


    On Wednesday, February 12, 2025 at 07:56:15 AM PST, Dave MacKay <dave at mdmackay.ca> wrote:  
 
 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 **

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/pipermail/triumphs  http://www.team.net/archive

Unsubscribe/Manage: http://autox.team.net/mailman/options/triumphs/yellowtr3@yahoo.com
  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/triumphs/attachments/20250212/9fe432c6/attachment.htm>