I guess I read his “undersize” wording but neglected to realize which was bigger, the tool or the journal. Since the tool is smaller it’s leaving more seal to be sized when the crank sits on it.
This is saying the seal is left 0.0029" tighter against the crank and not spaced away from it. I need more coffee.
Rich
PS Just found this too… from THIS post…
In reply to a message from MarekH sent Sat 16 May 2015:
The ‘‘factory’’ tool sourced from the Jaguar Club of North
America is SMALLER than the crank scroll by quite a few
thousandth’s of an inch. Sizing with this tool and using the
‘‘black’’ rope seal (‘graphite’ and sized so NO trimming is
required - sourced from one of our usual suppliers who is a
Jaguar dealer) will result in considerable drag. After all,
it is like an external brake. If you try to put a ‘‘white’’
seal in, the crank will barely turn if it is a ‘pattern’
seal which requires trimming as the one first supplied to me
wasn’t a very good fit in the groove in addition to being
too long.
Get a hold of a factory tool and measure it with a
micrometer, then measure the crank scroll. You’ll find that
there is a problem with either some of the tools or some of
the urban myths, some of the crank scrolls or all of the
above. I don’t sweat it as the crank turns, I used the
tool, it spun the same after each bearing was installed and
it ain’t gonna ‘‘burn the bearing’’ like some say.
Maybe I got the only defective Jag tool in the world,
maybe Jag changed the spec, maybe a lot of things, but no
way was the tool I got bigger than the crank scroll.–
The original message included these comments:
> The rope seal is not supposed to touch the crank. It works by
> having a tiny gap (~2thou) between it and the crank and running
> over a spiral groove cut into the crank. Any oil attempting to make
> its way out is pulled back into the engine by the Archimedes screw
> which is the oil groove and mild crankcase vacuum ensures that
> To achieve this, this seal has to be sized using a special tool
> which is essentially the same size as the crank plus a tiny bit.
> Failure to do this means that the seal will be sized ‘‘on the
> crank’’. This has the consequence that it will be gripped by the
> crank and and rather than pushed into the groove, can be pulled
around, rotated and concertina’d around the crank. This means that
there may be a gap between the two halves of the seal and oil can
escape if it has got past the metal to metal contact at the back of
the engine. A leak free engine is thus not guaranteed.
This is also the reason why the ‘‘sneaky Pete’’ method sort of works,
but sort of doesn’t work 100% of the time:- pulling a seal around
the crank necessarily deforms it and damages its ends.
It is also important to make siure that none threads of the rope
get caught between the housings as they come together. It is
surprisingly difficult and a skilled job to correctly size the rear
seal.
Aside from properly sizing the seal, you could attempt to get a gap
by temporarily using a couple of layers of metal tape around the
crank and tightening that to seat the seal further into its groove.
kind regards
Marek–
The original message included these comments: