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Crank rear oil seal
Posted: Mon Dec 20, 2010 1:01 pm
by DaveEFI
In the SD1 BL workshop manual, it mentions the rear crank seal mustn't be touched with the fingers when fitting. It looks like any other seal to me. Any ideas why?
Posted: Tue Dec 21, 2010 5:52 am
by minorv8
Worried about dirt perhaps ?
Posted: Tue Dec 21, 2010 9:38 am
by DaveEFI
minorv8 wrote:Worried about dirt perhaps ?
In the operating theatre that is my workshop?
Posted: Tue Dec 21, 2010 9:55 am
by softdash3.9
I've always touched mine when installing
Posted: Tue Dec 21, 2010 10:10 am
by DaveEFI
softdash3.9 wrote:I've always touched mine when installing
It came up on another group and I'm just curious as usual.
Things like headlight bulbs (halogen) aren't meant to be touched with the fingers as natural oils from those can cause the quartz envelope to fail (allegedly).
But the crank seal will have sump oil thrown at it.

Posted: Thu Dec 23, 2010 1:01 pm
by unstable load
I would have thought it would be so that the natural oily secretions of your skin don't contaminate the rubbing surface of the crank because your skin will cause corrosion.
It makes no sense that you should not touch the seal, though, it should read the metal, IMO.
I know on some of the helicopter bits I work on that you need cotton gloves to handle things like masts when fitting them to transmissions, specifically because of the damage that your skin will cause on contact with the steel.
Posted: Fri Dec 24, 2010 6:50 pm
by bigaldart
Makes no sense to me, any lip seal should be lubricated really, I have always given them a very light smear of oil before installing. Easy way to do that is with a finger, never had one leak on me if properly installed.
Alan
Posted: Fri Dec 24, 2010 8:48 pm
by mgbv8
bigaldart wrote:Makes no sense to me, any lip seal should be lubricated really, I have always given them a very light smear of oil before installing. Easy way to do that is with a finger, never had one leak on me if properly installed.
Alan
Same here Al !!
I've never had one leak and I put my greasy paws all over them ??
Posted: Fri Dec 24, 2010 10:52 pm
by kiwi303
Maybe that's because your paws are greasy? A nice insulating layer of hydrogenated dinosaur fat between your mitts and the seal?

Posted: Sat Dec 25, 2010 12:09 am
by ian.stewart
I wonder if its its made from a toxic material, or has a toxic coating
Posted: Sat Dec 25, 2010 10:09 am
by DEVONMAN
My take on this one is that the outside of the seal should be dry and clean when fitting so that it is firmly grabbed by the bearing cap. Any oil /grease on the outside of the seal may cause the seal to move over a period of time. Naturally the cap and block should also be dry but not the running lip.
Can't say I have been strict on this one in the past and have never had a problem.
Regards Denis
Posted: Sat Dec 25, 2010 11:08 am
by ged
I'm as guilty as everyone else. I've always oiled the journal & seal lip & had no problems but after a quick google I found this.
Read Installation Procedure about halfway down.
http://www.enginebuildermag.com/Article ... _seal.aspx
Don't know if it's relevant in our case so I'll carry on using oil on assembly.
Regards Ged