Oil Leak From Rear Of The Engine

[moto fugazzi]

I'm assuming that my rear main seal is leaking, but I won't know for sure until it's taken apart. Motor oil is leaking from the "slot" in the bottom of the bell housing.

 

My questions are:

What else should I replace as long as the tranny is out of the bike? Should I also replace the seal on that? It might also be a good time to replace the clutch disc(s), change the return spring, and lube the swing arm and wheel bearings.

 

My 2001 V11S does have 31,000 miles on it. I'm also going to have my dealer do it since he quoted me $500 labor plus parts. I wouldn't be able to do it myself until January in an unheated garage (In Wisconsin), and I'll get free heated storage from my dealer as well. 

 

Ken

[luhbo]

Docc just recently posted a link to a write up from P/R regarding rear leaks. The main seal in most cases is not the culprit.

 

Hubert

[docc]

The thread Bell Housing Leak has links to an excellent post by Pete Roper with great emphasis on the why and how of the crankcase vent being the likely culprit.

[moto fugazzi]

I'm trying to figure this out now. Here's according to Pete: When the clamp loosens or the hose cracks or collapses the hose leaks, it then runs down through the hole the pipe pokes through, through the bell housing and dribbles out of the drain slot and people who should know better say, "Uh! You've got a blown rear mainseal mate! That'll cost you a zillion dollars to fix!".

 

If the hose is bad or the clamp is loose, is it that the oil is not going up the hose and instead going downward towards the bell housing? I put a new hose on last summer, and I went to tighten the clamp today, and it looks like I stripped it. I'll replace it after work today. Here's a pic of the hose from today, and there's no fresh oil around that area.

[docc]

That looks clean. I suppose it's worth a new clamp. Pete details the other leak sources from the back of the engine besides the rear main seal. Unfortunately, they all require removing the gearbox to inspect and address.

[moto fugazzi]

I guess my point is that something is leaking back there. What else should be replaced as long as the tranny is removed? Should the rear main seal be replaced even if it isn't leaking as long as it's apart? What about the seal on the tranny? I'd hate to tear into this again a year from now in case another seal does go bad.

Ken

[docc]

For a comprehensive listing of possible leaks at the clutch housing, this still has to be the best-ever post on this topic by Pete Roper in the thread "Who's Smug Now?"

 

(With thread names like that, is there some wonder why searching the forums can be frustrating?

[docc]

 

If the hose is bad or the clamp is loose, is it that the oil is not going up the hose and instead going downward towards the bell housing? I put a new hose on last summer, and I went to tighten the clamp today, and it looks like I stripped it. I'll replace it after work today. Here's a pic of the hose from today, and there's no fresh oil around that area.

It was a revelation to me that there is a substantial gap around the vent pipe the "pokes through" the top of the clutch housing. If the clamp is loose or the attached hose is breaking down, the crankcase vented oil vapors will drain back down the hose and run through the bell (clutch) housing and out the lower weep hole.

 

fugazzi: what did you use for a replacement hose - MG part or one of the alternatives (heater hose)?

[moto fugazzi]

 

 

If the hose is bad or the clamp is loose, is it that the oil is not going up the hose and instead going downward towards the bell housing? I put a new hose on last summer, and I went to tighten the clamp today, and it looks like I stripped it. I'll replace it after work today. Here's a pic of the hose from today, and there's no fresh oil around that area.

It was a revelation to me that there is a substantial gap around the vent pipe the "pokes through" the top of the clutch housing. If the clamp is loose or the attached hose is breaking down, the crankcase vented oil vapors will drain back down the hose and run through the bell (clutch) housing and out the lower weep hole.

 

fugazzi: what did you use for a replacement hose - MG part or one of the alternatives (heater hose)?

 

I've read Pete's thread many times, but I think the tranny will have to come off unless there's a large gap around the vent pipe and the oil is draining down there without making a mess on top of the engine…I'll have a look later.

 

The hose is from MG Cycle, and I bought the check valve as well which I didn't install because the bike didn't have the valve installed when I replaced the hose.

Ken

[docc]

It seems to me that a valve there would only make things worse. Let's hope a good quality "fuel injection style" clamp will make a difference.

 

Nothing wrong with hoping!

 

Otherwise, it's crabbing the frame and good questions about whether to replace everything ("once and done"), or leave things alone if they are not the problem ("If it ain't broke, don't fix it"). 

[mznyc]

Any clutch slippage? If it's leaking from the rear seal oil should be on the clutch assembly.You can look through the timing site hole and see if there's any wetness in there.Some say pulling the motor is easier than pulling the tranny.I pulled the motor when doing the clutch last year.I would do the friction discs and maybe springs if they're close to service limits.Maybe push rod o-rings

[luhbo]

I guess my point is that something is leaking back there. What else should be replaced as long as the tranny is removed? Should the rear main seal be replaced even if it isn't leaking as long as it's apart? What about the seal on the tranny? I'd hate to tear into this again a year from now in case another seal does go bad.

Ken

 

I'd replace nothing as long as it hasn't definitely failed already. Seal rings for sure are delicate things, I never feel comfortable when working on or with them - so I let my fingers off as long as possible.

Same for the clutch. If it's working, don't replace it. You don't know about the quality the new parts will have.

 

Take the fly wheel off and check out the camshaft cover. My money is on this. Heat it up with an airgun, then apply brake cleaner and after that slow curing epoxy glue. As P/R wrote. I had this problem with my first 750 engine in the early eighties, didn't have it with the LMIII, then again had it with the V11.

 

Pulling the tranny is easier for DIY garages, but in this case you have to pull the engine because then you can lay it over and work horizontally either on the main seal or on the cover or/and definitely on the clutch springs. You have the tools for the clutch, BTW?

 

Hubert

[moto fugazzi]

 

I guess my point is that something is leaking back there. What else should be replaced as long as the tranny is removed? Should the rear main seal be replaced even if it isn't leaking as long as it's apart? What about the seal on the tranny? I'd hate to tear into this again a year from now in case another seal does go bad.

Ken

 

I'd replace nothing as long as it hasn't definitely failed already. Seal rings for sure are delicate things, I never feel comfortable when working on or with them - so I let my fingers off as long as possible.

Same for the clutch. If it's working, don't replace it. You don't know about the quality the new parts will have.

 

Take the fly wheel off and check out the camshaft cover. My money is on this. Heat it up with an airgun, then apply brake cleaner and after that slow curing epoxy glue. As P/R wrote. I had this problem with my first 750 engine in the early eighties, didn't have it with the LMIII, then again had it with the V11.

 

Pulling the tranny is easier for DIY garages, but in this case you have to pull the engine because then you can lay it over and work horizontally either on the main seal or on the cover or/and definitely on the clutch springs. You have the tools for the clutch, BTW?

 

Hubert

 

Thanks, Hubert.

I don't have any of the tools for the clutch, nor do I have a proper seal puller or driver to install a new seal. Couple that with the fact that I won't have time to work on the bike until January of next year (in an unheated garage with temps from 0f-32f), I'll have my dealer take care of this. They're honest, and they'll even let me observe the process as long as I stay out of the way. Not to mention that I've buggered up a few seals in the past, but that was 20+ years ago, and I've been intimidated by them ever since.

Ken

[luhbo]

 

... They're honest, and they'll even let me observe the process as long as I stay out of the way. ..

 

 

If you trust them, then a short 'fix it, please' is probably the best solution.

Attached you find a picture of my clutch at 120.000km when I sealed the camshaft cover using UHU-Plus. Only cleaned and slightly oiled the rusty parts and put all back in. Now at 170.000 the clutch still is just there, just nothing to mention.