Best way to fix camshaft rubber gasket leak

[DaveWatts]

Hi,

My bike is nearly ready now, except for one small oil leak (which is probably a TUV failure here in Germany!). I changed the rubber gaskets with a new set but they are still leaking from just below the rubber moon shaped gaskets. What should I do, put some gasket cement on there as well, try another supplier for the rubber gaskets? Any advice?

Thanks for any help

Dave

[fastbysuzuki]

If you are talking it's the half moon rubbers that are leaking when I install then I put a very light coating of blue hylomar around them let it flash off for 5 mins before installing them never had a problem after (if you try to install before it flashes off the rubbers have a tendency to slip and slide out)
This is assuming they are the correct size do they fit and follow the contour snugly and protrude above the gasket face so when you put the cam cover on it compresses the rubber.

[greg78gs750]

yes, a little sealant (not so much as to goo out) is fine, even "standard". Some like to install them lip-side in as well, as insurance from blowing them out. I have never felt the need, but....

[DaveWatts]

Lip side in might be a good idea, the oil pressure will help them seal better. I'll give that a go, along with some yamabond. Thanks for the ideas.

[gsrick]

Permatex Ultra Black RTV is my go to gasket sealer. Any that oozes out can be wiped off and it is black so if you miss any you'll never notice it.

[fastbysuzuki]

the oil pressure will help them seal better.

It would be a good idea to check your crankcase breather to see if it's clear there should be no oil pressure up there.

[DaveWatts]

It would be a good idea to check your crankcase breather to see if it's clear there should be no oil pressure up there.

Another good idea, everything looked clean but I'll blow through the hose next time the heads off.

[fastbysuzuki]

Not sure what bike you have but if you are running a standard air box any blockage would likely to be in the vary narrow passages where the breather pipe from the cam cover goes into the airbox this can be checked by disconnecting the hose and blowing down it to see if it's restricted.

[bwringer]

One thing I've found is that new half-moons often leak because it's very difficult to get them to compress far enough; they stick up a little, creating a gap between the gasket and the cylinder head. You can put a wee tiny bit of case sealer or (horrors) RTV on the corners, but you also have to watch this because it can sort of lubricate them a little and they can squirt out when you tighten the valve cover. Installing them backwards can help, or at least make sure they can't escape entirely.

Anyway... new half moon seals are one of those things that sounds like a great idea but usually end up being a complete ball ache. Re-use the old ones if at all possible.

If not, then do your best and keep a careful eye on them until they squish down a bit and stop trying to escape. I can't say whether there's much difference between aftermarket and OEM seals in this regard; both are problematic.

[DaveWatts]

It is a strange design choice by Suzuki, a two lipped half moon would be better (maybe I will make my own by gluing two together). I just wonder what is the purpose of them, why not just make the head surfaces flat?

BTW the breather hose blowed though fine.

[fastbysuzuki]

I just wonder what is the purpose of them, why not just make the head surfaces flat?

BTW the breather hose blowed though fine.

its to do with the machining process when the camshaft journals are being machined (horizontal boring accross the cylinder head)

[bwringer]

its to do with the machining process when the camshaft journals are being machined (horizontal boring accross the cylinder head)

Right, but why on earth couldn't they use a seal with two lips?

Never really figured out why this seal is basically designed to fail...

[DaveWatts]

Maybe the seal can be helped to do its job with some external pressure. I'm thinking the right sized piece of rubber sandwiched between the seal and the camshaft cover may increase pressure on the other seal. I think I will get some polymer clay and see how big this gap is. Another project I want to do is use some polymer clay to measure the distances within the air filter box and the outer cover. Then maybe I can get a 3D printed rubber gasket made up.

[Grimly]

yes, a little sealant (not so much as to goo out) is fine, even "standard". Some like to install them lip-side in as well, as insurance from blowing them out. I have never felt the need, but....

I got stranded once when one of those seals popped out, so ever since that I've installed them lip side in.

[limeex2]

New valve cover gasket, new half moons with Yamabond. Doesn't leak a drop. Never had one blow either.