372 clutch side crank seal dust lip.

[Sawrain]

Just wondering how most people are leaving the dust/dirt shield lip of pto/clutch side crank seals when working with 365/372s?

I seem to find them folded over, inverted from normal, like this this.



Just pushing the crank sleeve into a new seal can results in this, half the lip in and half out.




I normally flip them out, like this.



Just wondering after I noticed a picture of a seal lip half in, half out on a build thread here, and to give a warning to be carful when installing the sleeve.

I would have been happy to keep installing them dust shield lip out as a normal install, but finding them inverted in supposedly untouched saws had me wondering what others do.

 

[huskihl]

Never noticed it. I grease the seal lip and bushing and twist it in place. Only thing I try and make sure I don’t do is push too hard so that the spring comes out of place

 

[Mattyo]

I've liked the technique of installing the seal and bushing at the same time.... put the bushing into the seal...make sure it looks good inside and out...then seat the seal and bushing at the same time. Dont forget that stupid tiny fragile o ring as well

 

[thinair]

I just did some work on a low hour 365 and noticed the pto seal looked very similar to this but, it was torn also. Didn't know if it was common or not on these

 

[Mattyo]

If the seal is torn id be very suspicious of the bearings. If im suspicious....its getting torn down immediately.

 

[Ketchup]

Seems like inverted (first photo) would seal best. Good idea to install the bushing first though.

 

[Mattyo]

I disagree. Only half the seal was inverted. I would have made sure the lip is consistent all the way around. Another way to do it is to use the coke can trick. If the seal is already installed...you can use a piece of aluminum can between the bushing and the seal to make sure the lip doesn't prolapse and you don't knock out that spring internally.

 

[davidwyby]

Packing tape works for a seal slipper too

 

[Mattyo]

might be too flimsy? no? 35mm film works i've heard... maybe plastic from soda bottles ?

 

[Sawrain]

I've liked the technique of installing the seal and bushing at the same time.... put the bushing into the seal...make sure it looks good inside and out...then seat the seal and bushing at the same time. Dont forget that stupid tiny fragile o ring as well

I'll try that next time, will also ensure no dirt can fall into the seal when tapping it in, I like.

That O-ring is missing from some IPLs I think? It was only recently I worked on these saws, you were the first reference to that O-ring I came across.

I just did some work on a low hour 365 and noticed the pto seal looked very similar to this but, it was torn also. Didn't know if it was common or not on these

The last three, the only three of this model saw I have stripped to this stage have been like this, including yours that is 4, maybe they really are this way from new.

Seems like inverted (first photo) would seal best. Good idea to install the bushing first though.

If the main garter spring tensioned lip has failed to the point that sealing is reliant on the dust shield lip, you are already in trouble either way.

It might seal better against crank pressure in the inverted fitment, with pressure forcing it into the sleeve, but i doubt it would seal better against crankcase vacuum, and that leakage is more likely to cause failure.



Appears it is not a problem, as the 365/372 is rock solid.

But it is something to be aware of, as the seal dust lip is easily semi prolapsed, I noticed it in another build thread, that's when I realised I wasn't the only one to have this happen.

The picture in question.

 

[Mattyo]

With that last picture I would be seriously concerned about having popped out that seal spring and it failing a vacuum test.

 

[Sawrain]

I’ve never popped a spring off, they do fail the first vac test?

 

[Mattyo]

If the seal prolapse the spring pops out and you won't know it unless you vacuum test. I might hold pressure but not vac. This is why you need to do a coke can trick or put the bushing in the seal and install both at the same time. Either way pretty much ensures you to not prolapse the seal and pop the spring.