Velvet Drive Transmission Leak?

[Mundial]

Hi everyone:

I have a situation that I cannot figure out. I have just serviced my transmission (replaced seals and gaskets) and re-installed in on my Perkins 4-108 engine. After checking everthing I did a test run to make sure there were no leaks. To my surprise there was a leak from three holes on the flywheel cover on the right side of the engine. I'm sure that is not normal. I there something else wrong here? Or is the transmission seals leaking again? If I have to remove the transmission again I want to make sure this is the problem. Please help!

By the way, It ran smooth.

Mundial

[Chief Engineer]

Velvet drives have a history of front seals leaking due to pitting/scoring of input shaft over a period of time. The good news is that they make a sleeve that can be fitted to input shaft to repair it.

[shakey doug]

The Chief is spot on,it is surprising sometimes how little an imperfection has to be to cause a problem ,nyou can also buy a after market double lip seal slightly wider but fits ok.

[Mundial]

Thanks to both of you. I will make sure to check the shaft surface. I assume the shop that made the repair looked at all this, but you never know.

[Robert Laws]

I am repeating this post form the other VV leakage thread. Sorry to dulicate...

I know this is an old thread, but it is very useful, so I want to add a little more information. I have a velvet drive in my narrowboat in Cambridge (UK).

if the breather becomes blocked then the VV is then 'sealed'. As it heats up this means that fluid can be forced out past the lip seals. I found this was happening sometimes. The symptom was loss of fluid and also and that each time I released the dipstick it would 'pop' out like a Champaign cork!

I am posting this here as it also contains a discussio non VV keakage.

This is easy to solve of course: service or replace the breather. There's no need to remove the transmission.

In the process of looking into this, I took my breather apart. I found that it has only 4 parts: the body, the cap, a spring and a little rubbery 'pad' that presses down on the top the body. It is a one way valve: it allows air out, but not in.

[Kastaway]

How bad is the leak, is it slight, and only evident after some run time or is it larger ?

[Robert Laws]

The fluid level was about half a cupful below the fill line. Low enough that I was losing power to the prop, but certainly not right down to the lip-seal level. I topped it up and cleaned the breather. I also left the breather and filler a bit lose so as to be sure there is no pressure inside.

It seems to be holding it OK after 1 hour of cruising. But I will know more next week when I go back to the mooring (I don't live on board).

A narrowboat engine is not very demanding of the transmission: it's a 1950s BMC diesel engine from out of a London Taxi I think. It was marinized in about 1980, when the boat was built.