crank seals --- which way do i install??


rjardo

Member
May 21, 2007
4
0
k, dumb question here.
Yes i should have taken pics before tearing apart 2 mos ago, but i forgot which way the seals go in my YZ250.. should i see the spring or not? they go in after the cases are back together, so i have made it that far...

thanks

rj
 

IndyMX

Crash Test Dummy
~SPONSOR~
Jul 18, 2006
5,548
2
Amo, IN
Logic says to put the spring towards where the pressure is... I'd say to install the seals so that the spring side is towards the rod..
 

Bunya

Member
Apr 26, 2007
147
0
That's a good question really. The flaw in your logic Indy is the pressure side varies with crank position. During part of the cycle the crankcase operates under a vacuum which puts the pressure on the outside. Because sucking air thru crank seals can be catastrophic to the engine, my instinct would be to have the springs facing outward. I grabbed the Clymer manual for my RM to find out for sure. Unfortunately, it's only further confusing things:

NOTE
For the right crankcase, install the seal
with the open side facing out. For the
left crankcase, install the seal with the
closed side facing out.
:whoa:

Go figure! Looks like you should consult the manual for your bike. If you don't have one, you really should get one. Otherwise maybe someone will check their manual for you.

Marc -
 
Last edited:

rjardo

Member
May 21, 2007
4
0
Thanks for all the great replies, I am going to install with the springs in. they do have a double lip, so there is a slight lip facing out. when i really thought about it, it occured to me that it would be a real pain to press the seal on the spring side, with no flat face to press against. i would almost surely damage the seal getting it in, now with the flat, i only have a 50% chance of dorking it up :^)
Thanks again for all your replies and time...
RJ
 


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