ZF Gearbox leaks

[Philiz]

My Beneteau 9 series has a Volvo Penta badged ZF gearbox. A little while ago I changed the transmission fluid during a service, the filter wasn't changed as it looked spotless. I've had a very small oil leak since the job which a traced to the gearbox filter top cover, this has a 'O' ring arrangement which is compressed by the top thereby sealing it against the housing. I dismantled this again over the weekend, couldn't see any problems, cleaned everything up and rebuilt it, now the leak is worse than ever! Spoke to a local Beneteau engineer who happened to ber servicing a neighbouring boat but he says they never give trouble.

Only thing I can think of doing is to replace the 'O'ring although this looks perfectly okay. Anyone had this problem? Any suggestions? Maybe one for VolvoPaul if you're about!

Thanks in advance.

 

[cadser]

Have you tightened it too much and opened a crack up in the cover?

 

[Philiz]

Have you tightened it too much and opened a crack up in the cover?

Not that I can see, is that a common occurance do you know?

 

[spannerman]

These never leak if fitted correctly, the secret is to firmly press down on the cover while tightening so the O ring expands down in the hole, and not too much oil on it so it wont slide out easily.

 

[Philiz]

These never leak if fitted correctly, the secret is to firmly press down on the cover while tightening so the O ring expands down in the hole, and not too much oil on it so it wont slide out easily.

Thanks for that, I didn't put pressure on the top, just tightened the allen key bolt and allowed the lug on the cover to lock against the casing whilst tightening the bolt. I'll have another crack at it next weekend. Thanks again.

 

[Philiz]

Jusr remembered I forgot to come back on this one. Thanks very much Spannerman, did as you directed and sorted it. Cheers!