Help diagnose this oil leak.

[SmithSwede]

2013 V7 Stone with 65,000 miles.

There is a small, but persistent, oil leak on the right side of the engine where the transmission bolts onto the bell housing.   Also oil leaking from beneath the plastic plug that fits in the clutch inspection hole. 

What is the likely cause and fix?  Rear engine main seal? Some seal on the clutch push-rod?  Transmission seal?

I can’t tell if it is engine oil or transmission oil.   I can confirm that the transmission breather is  not clogged, and all obvious nuts and bolts have been tightened.   I also don’t think the oil is migrating from somewhere else—everything else seems to stay dry and just this area gets oiled up.

Clutch is not slipping, at least not yet. 

[rodekyll]

Your problem is that it's a smallblock.  When a big block leaks you know where it's coming from.     

I don't know crap about smallblocks, but if you pull the starter you can see in there pretty well.  Look for where the oil has been flung.  If it's ahead of the flywheel it's probably engine -- the rear main or thereabouts, or a leak into the bell housing from somewhere else.  If it's on the clutch side it's probably a tranny leak.

Try to get some on a q-tip and burn it.  Does it smell like burning oil or gear lube?  Can't tell?  Burn a q-tip of one or the other and compare . . .

[guzzisteve]

If it doesn't drip, it's seepage. Could be one of each you mentioned for cure. Smell the rubber plug oil on inside.

[pete mcgee]

My lack of knowledge on small blocks would fill a service book.
How ever I have had a lot of experience with oil leaks on pratt and whitney R2000 m7 radials......
First, a little bit of oil goes a long long way, leaks usually look worse than they are.
Looking at your photo it appears to be comming from the block join, which would be biggish repair.
It may also be either the enging rear main seal or transmission front seal, is any oil comming out of the drain hole at the bottom of the bell housing?
The other possibility is a small casting flaw in the engine block that lets just enough oil through to piss you off.
IMO, if its not dripping or losing oil from the engine or transmission, just keep an eye on it and keep cleaning it up as required.
If its really annoying you, winter IS comming and you lot up north like pulling things to bits to avoid cabin fever, it is however a lot of work for an oil smudge.....

[SmithSwede]

Thanks everyone.  Pulling the starter to look inside is a great idea.   I’ll do that soon.

I wasn’t aware there was a drain hole at the bottom of the bell housing.   I’ll look for that.

Pete, what do you mean by “coming from the block join”?  I was assuming that the seal between the transmission and the bell housing isn’t meant to contain oil, because in theory there shouldn’t be any oil in there.   Am I missing something?

I don’t care if it weeps a little oil; I’d put up with that indefinitely.   What I don’t want is an oiled up clutch, or a suddenly catastrophic seal failure that strands me in BFE. 

Is there anything significant to the fact that it seems only to be weeping from the right side, not the left?

[pete mcgee]

Just forward of the timing plug, roughly where your finger is pointing in your photo you will notice a join line on the engine block, there are a number of fasteners holding the top and bottom cases of the engine together and some sealant squeezed out in some areas.
A leak from there is possible due to a lack of sealeant, the join area not being completely flat or damaged, nicked or dented.
Have a look here
www.google.com.au/search?q=moto+guzzi+small+block+engine+assembly&oq=moto+guzzi+small+block+engine+assembley&aqs=chrome.1.69i57j33.32049j0j7&client=tablet-android-samsung&sourceid=chrome-mobile&ie=UTF-8#imgrc=pt2PMVbDZfgb1M:
Copy that link into google.
Youll see the upper and lower halves of the engine case have a horizontal join, inside of which is your crank and engine oil.
I hope that helps

[jlburgess]

Clean it up then douse it with talc and go for a ride.

[fotoguzzi]

wipe clean and report back after another 65,000 miles..

[tris]

OK - is it just me or does the picture appear and then disappear 10 seconds later?? 

[Triple Jim]

OK - is it just me or does the picture appear and then disappear 10 seconds later?? 

I have a feeling that one of the new Photobucket "features" rearing its head.  If I hit the ESC key when the photo shows up, it stays there so I can see it.

[SmithSwede]

Update. 

Pretty sure what is leaking is the stinky sulphur gear oil.  It is coming out of an unplugged weep hole in the bottom of the bell housing.

I drained the gear oil and after 6,000 miles I am  missing maybe 2 ounces of oil at most. 

Questions:

1).  Is it ok to just ignore this for tens of thousands of miles until the clutch finally wears out and gives me an excuse to get into this area?  On the one hand, I am fine being lazy.  I do not much mind if the bike is a bit oily or if it marks its territory. On the other hand, I ride the thing constantly, and long distances.  So I do no want to get stranded far away because I was too dang lazy and ignorant, and ignored an obvious and glaring problem rather than fix it.

2). What is the likely source of the leak?  I am thinking O-rings on clutch push-rod.   Far less likely the trans input seal.  Correct?   Or be prepared to replace both?

3).  If it is the O rings in clutch push rod, is it possible to remove and replace these O-rings by simply retracting the clutch push rod from the back of the trans?   I am thinking not from looking at the parts fiche, but I am no expert at this.  Do you have to remove and open the gear box to get at these O rings?

4). Any advice or comments welcome.   I am tempted to nuke the problem by replacing every possible seal that could be leaking in this area.   And maybe the clutch while I am in there.  But for all I know, that would be dumb, because certain seals basically never leak and messing with them makes things worse,  or it is obviously a certain O-ring, or my clutch should last another 60K miles.   

In other words, what would a small block Guzzi Guru do when faced with these symptoms?

[Antietam Classic Cycle]

Update. 

Pretty sure what is leaking is the stinky sulphur gear oil.  It is coming out of an unplugged weep hole in the bottom of the bell housing.

I drained the gear oil and after 6,000 miles I am  missing maybe 2 ounces of oil at most. 

Questions:

2). What is the likely source of the leak?  I am thinking O-rings on clutch push-rod.   Far less likely the trans input seal.  Correct?   Or be prepared to replace both?

Small-blocks (at least older ones with five-speed transmission) don't have o-rings on the clutch pushrod like big-block Guzzis, but rather a "normal" seal. #11 in this illustration:
http://www.stein-dinse.biz/bilder/auto/breite_800/303033393041.gif


It fits into #12 which is only accessible by removing and disassembling the transmission, IIRC.

It might be #20 in this illustration:
http://www.stein-dinse.biz/bilder/auto/breite_800/303033393040.gif


I'd replace both and any o-rings that might be involved.

[pehayes]

BTW, that seal as described by Charlie is odd.  Normally, when you add a seal, you are looking from the outside.  In this particular instance, you are looking at the seal from the inside as if you were a molecule of oil. So, keep that in mind as you install the seal.   Once installed, you are looking at the BACK SIDE of the seal.

Install like this:





Patrick Hayes
Fremont CA

[SmithSwede]

Thanks.  So it sounds like there isn't an "easy way" to attack this issue.   Any seals I need to replace requires pulling the transmission off, removing the bell housing, and perhaps also cracking open the gear box.   I think opening the gear box requires some special tools.

Not sure I'm following the stuff about looking inside versus outside.   I think what is meant is that the false input shaft is removed, and maybe some other stuff.  Then the seal is placed in the proper location and oriented in the manner shown in the photograph.

In other words, I don't think this means to press the seal downward from the outside down into the false input shaft.   

[Antietam Classic Cycle]

There are some videos that might help here: http://thisoldtractor.com/moto_guzzi_technical_training_videos_eng.html

Scroll down almost to the bottom.

[Chuck in Indiana]

It would have to leak pretty badly before I'd get concerned..  After sitting for a couple of weeks, my Monza has a drip from the bell housing. Pffft. I'm an antique airplane guy. I know what a leak is. It requires a container..

[SmithSwede]

Preach it, Brother Chuck !!!!

I’m just begging for some smart folks to give me their sincere opinion that this situation may be a bit messy, and it does not require immediate or drastic action.   I’m fine with the “wait and see” approach.   Don’t care about a bit of oil.

Problem is I ride this thing constantly and *depend* on it to reliably get me from A to B.  So I don’t want to be kicking myself should it fail catastrophically when I’m in BFE.   Only for that situation to be made worse by smart gear head people telling me I’m an idiot who should have fixed this known and obvious a long long ago!!

Maybe I should start a poll.   Should the Swede be lazy, buy paper towels, and mop up a bit of oil?   Or is this a tell-tale sign of mechanical doomsday that requires prompt and drastic action?

[voncrump]

How about trying some seal recovery/saver type of oil next time you do an oil change on the gearbox. I changed the gearbox oil on my 1100 sport years ago . I used the latest and greatest synthetic oil. It pissed out. One of my Guzzi friends gave me some 85/140 truck gear oil and said try that with a bit of stop leak from STP. No more leaks.
Cheers, voncrump. Also check the breather and the amount of oil in the box..

[sign216]

Maybe I should start a poll.   Should the Swede be lazy, buy paper towels, and mop up a bit of oil?   Or is this a tell-tale sign of mechanical doomsday that requires prompt and drastic action?

My 2 cents; it's a machine, it gets used.  And so it drips some oil.  No problem.

Talk to the guys that owned vintage Brit bikes.  They dripped right from new!

[rudolf35]

As noted above, clean it up, ride it and keep an eye on it for the next 50k.  oh, almost forgot, shoot it if it moves.

[normzone]

My 2 cents; it's a machine, it gets used.  And so it drips some oil.  No problem. Talk to the guys that owned vintage Brit bikes.  They dripped right from new!

I watched my first motorcycle mentor (George C. Alvarez, where are you ?) build a basket case pre-unit '57 Triumph engine - it literally began leaking oil before he put any in it.

[pete mcgee]

Keep an eye on it.
Check gearbox oil level every week or so and check before any big trips.
When it starts leaving puddles do something about it.

[Chuck in Indiana]

Uhhh, this 90 hp Lambert radial was test run, drained, and pickled in the late 90s. It hasn't had any oil in it since then. There are some serious drips of oil  underneath it. 
2016-03-05_05-00-17 by Charles Stottlemyer, on Flickr
This picture was taken a couple of years ago. It's much worse, now..  A little oil goes a long ways.. it's like blood. Looks like crap, doesn't hurt much. 

[SmithSwede]

I failed to close the loop on this thread and got a PM from a forum member looking for the resolution. 

Turns out this leak was caused by a totally shot transmission input bearing, along with a worn and partially fractured clutch.  The leak just got worse and worse until I got into it, replaced the clutch, the bearing, and all seals.  That stopped the leak.

The old seals looked ok, and were not obviously worn or damaged.   I think the bad bearing caused wobbling or weird vibrations such that the seals could not seal.

The failed bearing was downright scary.  It would not have lasted much longer.  The cage was broken in pieces, and when I took it out I could manipulate it to cause the balls to fall out.

I think it would be bad to be traveling at highway speed if that bearing totally failed. Personally, in the future, I would not ignore a persistent transmission oil leak on a small block.

Perhaps I just got a bad bearing, but I heard from a Texas Guzzi pro that this bearing is kind of the weak link in a small block transmission.  I suggest inspecting, and likely changing it, whenever you do the clutch.

[malik]

Well, that's timely. The Special is in pieces to replace a slipping clutch - oil had travelled up the clutch push rod onto the cup & thence the clutch. When I removed the "clutch drum" from the "transmission cage" to get to the pushrod & it's seal, I found several flecks of bright metal (magnetic) in there. A bit of a worry.

Which bearing is your "transmission input bearing"?

The bearing on the transmission shaft (which has the pushrod seal on its inner end) came out stuck on the shaft, but seems to runs freely. The bearing in the transmission cage that the transmission shaft goes into (the 6004/C3) is grating a little. I'll be pricing those with the local bearing shop later today. I've been having difficulty separating the transmission cage from the cover to get to the innards of the gearbox to clean & inspect further (that bloody nut on the end isn't budging & it's only supposed to have 60Nm on it) but I've a couple of ideas to try for easier access & better purchase, so it should be off today. The saga continues. It was supposed to be quick & easy, as I've done it before, but in this one I've run into all sorts of problems, difficulties, complications. Luck of the draw, I guess (we shall not mention incompetence & ignorance).

Oh, the obligatory pretty picture - or it didn't happen.

[sign216]

SmithSwede,
Good information about the bearing.  Like Malik, I ask :  which bearing is the problem one?
Joe

[SmithSwede]

The bearing that failed on my bike is GU 920 01 225.  It is the one on the bell housing, fixed in place by the “fixing plate” which is GU 192 03 460.  I don’t think there is anything special about this bearing and I bet you could source it from a bearing house.

Mine was also stuck on the shaft when I removed it, and it was very obvious it was shot.

I thought long and hard about opening up the gear box and digging deeper, but everything else seemed ok and spun freely with no noises.  The guru told me not to worry about the gear box innards and to just replace the obviously bad bearing.   Which has worked so far (I’ve done about 30K miles since replacing the clutch and bearing).

But if you are hearing anything funny in the gear box, I’d dig into it.

Now here’s a mystery.  I looked at a lot of old Guzzi manuals while working on this.  The older ones said to put Locktite sealant on the outer surface of the bearing.    The newer ones didn’t say anything about using sealant.   I decided to seal it with blue non-permanent Locktite, figuring it would not be good to have it spin in the housing.   It doesn’t seem to be a very snug fit in the first place.  I figured it would be easy to put a lot of heat in that area if the Locktite gave me trouble the next time around. 

[SmithSwede]

Reply # 11 above has two charts.  Look at the chart on the bottom, showing the bell housing and clutch—I’m referring to the bearing labeled #10.

One other thing I should have mentioned.   I was getting what I thought was a moderate amount of swarf on the magnetic drain plug on the transmission.   Nothing longer than 1mm, but enough to completely cover the magnet, and the stuff was sharp and jagged feeling when I would rub it between my fingers.  I was prepared to ignore this and was going to see if it got worse. 

After replacing the failed bearing, I get virtually no swarf on the transmission plug. 

So that’s probably a good sign of bearing trouble.  And since this bearing was totally shot, I don’t think waiting to see if even more swarf appeared would have been a good strategy. 

[n3303j]

Any time I find "sharp and jagged" I know it's time for an autopsy. Sharp and jagged indicates failure of a hardened surface (bearing or gear face). These particles are harder than a file and are being circulated through the precision parts of the unit using that oil. Transmssion and final drive have no filtration. Sharp and jagged swarf is damaging every close fit it passes through. Close look with an inspection  microscope will reveal the surface damage.

[nealwp]

You can normally tell gear oil by the smell. It has a stronger oder than motor oil.