Oil leak

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dav
Posts: 21
Joined: Sun Jan 10, 2010 9:50 am

Oil leak

Postby dav » Sat Dec 31, 2011 1:33 am

Hi all, On my (our) 1968 MK3 there's a oil leak (flow) coming out of the chain sprocket output shaft after a decent run(oil very warm), took off the side case & sprocket & there's no seal or anything that stops any oil from coming out, plus the books show no seals etc..in that area. So does anyone know why or how to stop the oil from coming out.
Besides the oil leak the bike runs perfect.

Thank you, Davin.

Jon Pegler
Posts: 459
Joined: Sun May 16, 2010 6:19 pm

Re: Oil leak

Postby Jon Pegler » Sat Dec 31, 2011 3:07 am

There is no seal as such fitted behind the gearbox sprocket.
Sealing is achieved by the use of a rubber sealed bearing fitted inside the engine cases.
If the leak is bad, the motor will have to be stripped and new rubber sealed bearings fitted.
The other cause of an oil leak in that place is caused by having your motor filled with too much oil.
Check the oil level first, but I would guess that the motor will have to come apart sooner rather than later.

Jon

wcorey
Posts: 323
Joined: Sun Jan 31, 2010 1:50 am
Location: MA USA

Re: Oil leak

Postby wcorey » Sat Dec 31, 2011 3:38 am

Also check that the crankcase vent tube is not being pinched or blocked. Adding a PCV valve may help a bit...

Bill

MotoMike
Posts: 487
Joined: Wed Aug 04, 2010 3:40 am

Re: Oil leak

Postby MotoMike » Sat Dec 31, 2011 4:58 am

Hi Davin
Make sure your oil level is not too high. DCT Bob pointed out that when he has seen this it was sometimes the result of a forgotten fuel shut off petcock and that raw gas had raised the level of the crankcase. If your engine is getting tired and has a fair amount of blow by it could contribute to this symptom. I fitted a PVC valve in my crankcase vent line and it seemed to have corrected it for me.

Mike

DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

Common Oil-leak Issue

Postby DewCatTea-Bob » Mon Jan 02, 2012 4:23 am

____ Good/solid post/info by MotoMike above !

dav wrote: there's a oil leak (flow) coming out of the chain sprocket output shaft after a decent run(oil very warm), took off the side case & sprocket & there's no seal or anything that stops any oil from coming out,
____ Unless you park your Duke by steeply leaning it to the right-side (against a wall or something), the intended/expected (3-qt.+) oil-level should not reach upward high enough to leak out through that point !
Even so, that oil-leak issue has long been a common-problem for DUKEs used by riders who don't bother to shut-off the fuel-petcocks whenever the engine is not running ! _ When a petcock is often left turned-on, it then doesn't take a real long time before the fuel in the tank leaks through the carb & down into the crankcase-sump enough to raise the oil-level upward. _ And when such oversight continues-on unchecked, then the oil-level eventually reaches-up to that transmission-shaft's height-level (even when the motor is kept straight-upright).
__ So whenever such excessive/noticeable oil-leakage occurs at that point, then realize that it's likely already past-due to refresh/change the contaminated oil.
(Good-thing that a DESMO doesn't have as much valve-spring tension to help score-up the cam-lobe surfaces when the oil gets diluted !)
But hopefully in this case, the issue isn't due to ignored petcocks,, but rather, because someone brought-up the oil-sump's oil-volume well over 3-quarts by possibly not getting most-all of the previous/used motor-oil dumped-out, before then adding the specified-amount.


Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

dav
Posts: 21
Joined: Sun Jan 10, 2010 9:50 am

Re: Oil leak

Postby dav » Tue Jan 03, 2012 10:29 am

Cheers guys for the replies. Its not the over filling of oil or the petcock, i check the oil level before every run & after every run. We have decided to split the case to have a look at the 'sealed' bearing. Will let you know the out come when he gets to that bloody bearing.

Cheers, Davin.

DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

The Oil-leak from behind the Drive-sprocket

Postby DewCatTea-Bob » Tue Jan 03, 2012 8:46 pm

" Its not the over filling of oil or the petcock, i check the oil level before every run & after every run. "

____ Then your particular oil-leakage issue doesn't seem to make expected natural/reasonable sense, concerning a motor which otherwise runs "perfect" .
__ Next-time you dump-out your (entire!) oil-sump/volume, then take & measure it so as to determine exactly how much oil you actually had in it ! ... Could be that (like many Duke-owners), you haven't realized that the motor will not drain-out completely by just merely removing the drain-plug/(strainer-tube), in order to remove ALL the contained/used-oil within,, as the motor must be tilted both right & left (after being stood level between tilts), at-least* a couple of times (in order to get all the internal-cavities drained-out), (*depending on how hot the oil is at the time).
____ Here follows links to a couple other directly-related threads which were started in the past, on this same subject/topic...
viewtopic.php?f=3&t=337
viewtopic.php?f=3&t=426


Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

joe46ho
Posts: 247
Joined: Mon Jun 20, 2011 10:45 pm
Location: Erlanger, Ky
Contact:

Re: Oil leak

Postby joe46ho » Wed Jan 04, 2012 5:25 am

Davin, Along the same lines as what bob said. If your engine has no other problems, i would seriously consider doing a few more checks before tearing into it. I have noticed that some reproduction dipsticks for instance are inaccurate (probably some factory ones also) and make sure there isnt debris wrapped around the output shaft/sprocket area that could have forced itself into the case, and maybe the seal of the bearing also, however unless it was omitted at the factory, or by a previous rebuilder, there is a spacer/washer/shim, whatever you want to call it... that is supposed to help guard against this (ducati part # 0400.49.210) its just a 20.2x38x0.5 mm hardened washer/shim if all the parts are installed correctly and you have the correct oil level, i find it hard to imagine there could ever be much of a leak, even if the seal in the bearing was destroyed, the washer covers up the seal, and the sprocket seats against all of it. also do you have a oem sprocket ? and is it tight ?

There is one other thing you could try, in the interest of putting of splitting the cases for now, or possibly forever...
its an idea im sure would work but would require care/skill to do properly, im not sure of your mechanical skill level, and what tools you have at your disposal... but here is goes...
Get a spare sprocket, or use your original if you have access to a lathe and know how to use it, and cut an o-ring groove the appropriate size in the sprocket o.d. , then fit an o-ring in the groove, this will seal between the o.d. of the sprocket and the engine case bore/hole, im confident if you did this correctly it would work, you will ALSO need to clean the splines thoroughly and apply some hylomar or other sealant to them. The oil will have nowhere to go but back into the case/gearbox. If you do this I would consider this a permanent fix, and I would not even think of splitting the case, unless you have other problems down the road... and of course if you ever replace your sprocket for wear, you will need to machine your new sprocket with the same groove.
If you really are unsure about machining on your sprocket, and you dont have a spare, let me know which tooth count you have, and pitch. 428/530 ? (you didnt mention if your mk3 was a 250/350/or 450 so im not sure what you have). I have a few spare sprockets, I might have one.
ONE OTHER VERY IMPORTANT THING I FORGOT, I was writing this as if I would be doing it on my brothers 450 engine sitting here on my engine stand, however it should be noted that the factory type sprockets have a spiral groove in the od of the sprocket, where as the talon sprocket on this 450 im looking at does not, im attaching 2 pics of it so you can see the difference, honestly if you are going to go to the trouble of doing this, unless you have a like new sprocket, i would consider buying a new one, i got this one from lacey engineering they are very reasonably priced. You could also cut down the entire od of a factory sprocket smooth, then cut your groove, and fit a thicker o-ring, but that is up to you. I think either way would work...

cheers... Joe
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Too many projects to list...
12 Ducati singles currently

Rick
Posts: 340
Joined: Thu Nov 11, 2010 1:12 am
Location: Northern Plains, USA

Re: Oil leak

Postby Rick » Wed Jan 04, 2012 6:55 pm

These discussions are really useful to someone in my situation- assembling basket case engines. When I looked at the part diagrams it was a little confusing- it looked like the washer on the inside of the crankcase would keep the bearing from seating against the case, so I did some measuring and drawing.
My crankcase looks to have a sleeve inserted into the bore for the countershaft bearing- the important thing is to see that there's a shallow clearance pocket for that inside washer to sit in.
countershaft bearing.jpg

I made a drawing to clear up what these washers were doing- the inside is part# 0400.49.210, and the outside washer is # 0603.16.055.
I don't have a sprocket laying around, so I took a guess- the length of the nose on the sprocket isn't important for the drawing.
If I got it right, both the yellow inside washer and the red outside washer will be clamped to the countershaft and rotating with it.
widecase sprocket seal.jpg

The inside washer is thinner than the pocket formed in the case by the 'insert', and the outside washer seems to be just a shim- maybe to get the sprockets aligned.
The nut on the countershaft will pull the sprocket, 2 washers, and the bearing together, but the shaft isn't constrained in the case by this assembly- the shim and bearing in the crankcase at the other end of the countershaft keep the shaft from floating axially.
So, I intend to check the thickness of the inside washer, the OD of the outside washer, and shim the far end of the countershaft to keep it from floating too much.
If anyone sees an error, let me know.
Rick
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Rick
Posts: 340
Joined: Thu Nov 11, 2010 1:12 am
Location: Northern Plains, USA

Re: Oil leak

Postby Rick » Wed Jan 04, 2012 7:07 pm

I should have added that the inside washer looks to me to be just a shield for the bearing- with a double sealed bearing it may not even be needed- water could get around that inside washer anyway. Plus, if using the inside washer, the OD needs to be smaller than the ID of the insert/pocket.
Rick


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