Oil leak and crankcase bolt torque question...

[HP 59]

Hey
if there is only sweat oil at the engine than I use OMNI visk 1002 - that's a total clear silikone based sealing paste.
I had used that many times at my enfield and race bike when some oil film gets out of sealed areas.
But I have no idea if you can find it in in the USA.

regards
HP

[Jordan]

Hi HP,

Just a caution. You have good experience with silicone sealant, but note that it went out of fashion for motorcycle use after a brief popularity. When used too liberally, it caused problems when excess would sometimes clog oil passages.
These days "3-Bond" (Yamabond, etc) sealant is used instead. It seals very well but doesn't create beads of rubber like silicone does.
It's usually grey for the standard stuff, or white for use with water cooled engines. It's available at many motorcycle shops.

Jordan

[LaceyDucati]

Hi Jim
One of the common culprits is the oil filter seal, quite often mistaken as a crankcase leak, worth checking. Loose engine bolts can also lead to a centre joint leak, so try the engine bolts. In my opinion no sealant should be necessary on good paper joints, just a thin film of oil or grease. To my mind putting sealant on gaskets, doesn't make sense. Sometimes if a casing is damaged it may be necessary to add sealant locally in that area. I would always use a setting sealant, like a good quality silicone or something like 3 bond. Loctite 574 is good for centre cases if you are not using a gasket, although it's a bugger to clean off when you strip the engine (needs care).

I would never use Hylomar as it doesn't set and tends to end up in loose blue "bogies" circulating your engine. I've seen many a filter clogged in blue snot!

Nigel

[kmev]

I would never use Hylomar as it doesn't set and tends to end up in loose blue "bogies" circulating your engine. I've seen many a filter clogged in blue snot!

That's actually why I prefer Hylomar - as it does not set. I've seen motors from other marques that were seriously damaged due to a loose chunk of hardened silicone completely blocking an oil passage. Neither sealant should be overdone, but for myself - I'd rather clean an oil filter than track down a blocked oil passage that probably caused some significant damage.

[LaceyDucati]

Each to there own & as you say "use sparingly".

If the cases are degreased & used sensibly I have never found silicone comes loose. However most floating silicone I think comes from careless cleaning when the cases are removed and cleaned (or not!) before re assembly. I hate clear silicone with vengeance as it is difficult to see on a face, blue & orange looks naff, grey or black is much better. As for Hylomar and it's like (and other misused sealants), places to be most careful is around the timing casing and base gasket oil ways. The oil feed dowel in the head has a 2mm hole which can easily be blocked by a stray bit of sealant. On a race bikes I nearly always use sealant & shims on the base joint to maintain an accurate squish, so I have a lot of experience of sealant in this area. Never had a problem yet, but care and paranoia are a good idea!

As for centre joints on singles, I never use them, I use Loctite 574 & shim accordingly

Other common leaks I see are:

Bevel cover and clutch inspection gaskets often leak due to distorted covers. Just age and repeated use of gaskets causes it. Fitting a new gasket on a distorted cover will only make the leak worse! A quick lap down on a sheet of wet & dry on a plate soon sorts the problem.

Oil Banjos, as the early un-flanged bolts over time & over tightening cause the banjo to distort and bow in. Later flanged bolts are much better. A small smear of Loctite 572 paste on the alloy washers will stop minor weeps.

Regards Nigel