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Gearbox leak


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#1 gregg877

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Posted 07 April 2015 - 01:28 AM

Hey folks,

My Dnepr mt11 has had a leak comign from somewhere between the engine and gearbox. The oil is relatively clear, the engine oil is black, so I'm guessing it's got to be somethign in the front of the gearbox (input shaft seal or something). I finally got around to removing the gearbox and on inspection I can't tell where it's coming from. There was a lot of grime on the front of the gearbox but nothing obviously wet. The main seal on the input shaft appears to be dry and intact. The flange looking thing is a little wet and the screws appear to be gorped pretty good. I tilted the gearbox on the bench and spun the output shaft on the other end to see if I could get something going...and nothing. The flywheel and pressure plates appear to be dry, in fact they are a little on the rusty side. I'm a little stumped here.

I did get a complete set of seals and o-rings for the gearbox; is there something that goes under the flange that is prone to fail? I'm a little apprehensive about taking anything apart if I don't have to.

As always advice and or guidance is appreciated.

Thanks, Gregg
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#2 MotoJ

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Posted 07 April 2015 - 08:07 AM

Sure it's not just water that seeped into the clutch cavity?
If it's oil and it's not coming from the gearbox it could only have been coming from the rear seal behind the flywheel.
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#3 razorlight

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Posted 07 April 2015 - 03:59 PM

It could be the "flange looking thing". The flange with the 2 screws is the kickstart tensioner. It has an O ring behind it, mine had disintegrated, but I did manage to repair it. Might be worth having a look at the post "Dnepr reverse gearbox leak" on page 4. Hope it helps.
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#4 gregg877

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Posted 07 April 2015 - 05:18 PM

Found my culprit, inisnthe kick start tensioner, the o-ring is intact, but both screws are horribly gorped. The top screw hole is over size, so im goig to have to make a new one and re-tap the hole.

I made the mistake of unscrewing both and trying to sneak out the flange to inspect the o-ring. I felt tension on the flange and then a release of tension, so my question is do i have to open up to gearbox to fix it, or is there a way to cheat?
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#5 sallen

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Posted 07 April 2015 - 09:42 PM

Deleted first post.
The retaining screw holes are drilled and tapped through the case.
You will have to dissemble the transmission if you are going to rethread the holes

#6 lobofuego

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Posted 10 April 2015 - 05:43 AM

Re, the engine oil leak thing...Breathing...its all about it and whilst a timed exit valve is ok, the breather going into the airbox is inefficient, due to it not being subject to high flow, and not therefore inducing a "suction" force on the exiting vapours, and helping to lube valve guides etc....the idea being ..as per a 2cv...that you create a negative pressure within the crankcase, that the oil , does not escape...at all!....So my solution to this is to replace the breather tube with a nice piece of copper pipe, (polished and lacquered!) to fit from engine to air filter and to sit directly into air flow of L/H, carb inlet, tthis creats a suction into the breather not allowing gas in and assisting in gas out....do realise that this does add a small amount of "hot" air into inlet tract, but ....not a bloody Ferrarie is it!...and performance , for me remains .."normal"

#7 gregg877

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Posted 28 April 2015 - 10:26 AM

Hey folks,

Finally got down to it. The leak was coming from the kickstart tensioner. I don't know if It was a factory thing or what, but the top screw hole was oversize with no threads and the bottom screw was pretty gorped up.

I repaired the top hole with a M6x1 timesert and chased the bottom hole with an M6x1 tap; new screws for both, a new o-ring for the tensioner and proper tension set for the kickstart lever. I've got the gearbox back on and am slowly putting everything back together now.

All that said I'm having a massive brain fart looking at all of the nut's, bolts and other stuff I've tried to keep organized; can somebody please post a picture of the location of the clutch cable bracket near the clutch arm? I've got the bracket, cant remember exactly what it was attached to.

Thanks, Gregg
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Nothing worth doing is easy...

#8 sallen

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Posted 28 April 2015 - 09:39 PM

On my Dnepr it mounts on the transmission stud with the pinch clamp on the bottom.




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