372 XP Clutch Side Crank Seal

[eriklane]

log_jammer-thanks, and that's what I did. Hmm. So that tiny O ring just lays against the bearing. Well it's still leaking, and even after I slammed some grease in there, it leaked less, but, still leaks. What a strange design. Not sure what to do next.

 

[super3]

puy the clutch on to seat the o ring

Are you doing this when checking vac/pres?

 

[Mattyo]

is the bushing new? make sure its a new seal, new bushing, and obviously new o ring.

are you getting bubbles at the bushing/seal or between the bushing/crank?

 

[eriklane]

The bushing isn't new, but the O ring was and I reassembled this case last year, new crank seal then.With the bushing out, it is leaking at the union of the crank and bearing.

 

[blsnelling]

puy the clutch on to seat the o ring

Are you doing this when checking vac/pres?

I haven't seen this question answered yet.

 

[blsnelling]

is the bushing new? make sure its a new seal, new bushing, and obviously new o ring.

Why a new bushing? I have never replaced one.

 

[blsnelling]

With the bushing out, it is leaking at the union of the crank and bearing.

I don't see how this is possible. The case is wide open without that bushing.

 

[super3]

Why a new bushing? I have never replaced one.

Those who have and those who will.

 

[Mattyo]

The bushing isn't new, but the O ring was and I reassembled this case last year, new crank seal then.With the bushing out, it is leaking at the union of the crank and bearing.

the union of the crank and the bearing? the bearings are pressed onto the crank. ... or the crank is pulled through the bearing (semantics) ... so... how in the world can you have a leak here?

there are 3 places you can have a leak when the assembly is together. the crankcase/metal seal ... the rubber seal/bushing ... and the bushing/crank.

so which one is leaking? ... did you see my vid?

 

[eriklane]

With the bushing in, no air comes out between the big seal and the bushing. When I remove the bushing, and pressure test, I can see bubbles at the point where the crank and the bearing surfaces mate. Isn't the O ring supposed to seal what should only be a very tiny possible leak between the crank and the bearing race? Now does the clutch have to be on or can I test with it off? I have it off...

 

[ANewSawyer]

I know nothing about the saw but from watching Mattyo's video, shouldn't you be testing with bushing in place and the o ring under it? I don't think you could get it to seal without the bushing, but what do I know!?

 

[Mattyo]

why would you remove the bushing to pressure test? the bushing is an integral piece to creating a crankcase seal...

 

[Mattyo]

i am now convinced he didn't see the vid...

 

[Justsaws]

Pretty sure if the crankshaft to bearing mating surface is leaking you would need to test with the bushing in place over the o ring or else it will have no force applied to the o ring to form a seal. Basically have to test with the clutch installed, perhaps not or at least not fully torqued. Would like to think the outer seal would hold it in place, maybe not. Seems a weird situation.

A well used saw will need a new bushing, also if the bushing has been heat blued it should be replaced as it may no longer be round.

In the last couple months have done 6 365/372 crank and or bearing replacements, have not had issues such as this. It would be frustrating. Hope you get it sorted, good luck.

Have another sitting on the bench now, probably just jinxed it, gonna be a leaker.

 

[John Stryker]

With the bushing in, no air comes out between the big seal and the bushing. When I remove the bushing, and pressure test, I can see bubbles at the point where the crank and the bearing surfaces mate. Isn't the O ring supposed to seal what should only be a very tiny possible leak between the crank and the bearing race? Now does the clutch have to be on or can I test with it off? I have it off...

The outer shoulder of the bushing seals against the seal, and the o-ring seals between the crank and the inside of the bushing. So you have to have the bushing in, and held down by hand, or with the clutch installed for an effective seal. Also the 2 oiler bolts have to be in and I put a bit of sealant on them too.

 

[K5krawler]

I ended up getting the saw fixed several years ago haha! It seemed to stop leaking after I assembled everything including the clutch.

 

[eriklane]

i am now convinced he didn't see the vid...

I watched it, I was mostly confused on exactly where the O ring seats and what space it's taking up. I blew on the tube and bubbles came out around the main crankshaft, so the main seal must be bad.

 

[John Stryker]

I watched it, I was mostly confused on exactly where the O ring seats and what space it's taking up. I blew on the tube and bubbles came out around the main crankshaft, so the main seal must be bad.

The o-ring sits on the crank shoulder underneath the bushing. Then you hold down the bushing and pressure test.

 

[eriklane]

Yeah, it's just so tiny and you can't see what happens once you push the busing on, ergo, what the hek is that thing doing/what is it for? Seems to me it's making sure there's no leak between the crank and the bearing and I guess also the bushing. Then the main crank seal is for the outside of the bushing.

 

[John Stryker]

Yeah, it's just so tiny and you can't see what happens once you push the busing on, ergo, what the hek is that thing doing/what is it for? Seems to me it's making sure there's no leak between the crank and the bearing and I guess also the bushing. Then the main crank seal is for the outside of the bushing.

The o-ring is really only for sealing the bushing to the crank. You'll see, it will work once it's all back together.