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I had a decent weep coming from the base of my cylinder head.
I didn't use the o-ring at the base before because I was told it wasn't needed if some gasket maker was put there.
It seems that the gasket stuff didn't do the job and after pulling the head I can see why, not uniform in it's distribution.

so, I have the o-ring, I plan on using it. Should I add a small amount of silicon gasket junk too or leave it be?

Silicone seal will screw up an o-ring seal. Never use them together.

Are you really talking about the cylinder head, or the base of the cylinder where it meets the case?

Major Softie wrote:Silicone seal will screw up an o-ring seal. Never use them together.

+1

Here's what I posted last October. It works well. I use no base gaskets, and I hand beveled my 78 block to accept Nikasil cylinders.

Re: Cylinder base oil leaks

Postby RDG » Thu Mar 03, 2011 5:42 pm
I've tried the Yamabond, 3 Bond, the this, that and the other thing. Best sealer I've found was Permatex Sealer, it's brownish and stinky- oh behave! A machinist insisted this was the only thing they used on aircraft engines...But what sold me was he used it on his racing BSA and no leaks? NO LEAKS? I saw it for myself!

The liter boxer's are notorious for seeping around the cylinder base. My 78S is dry, even after a hard run. Preparation is most important. Assure all surfaces are extremely clean, wipe down with denatured alcohol...use surgical gloves, make it clean! Use your fingers to smear just enough to make a thin film on both surfaces....Wait about 15 min. When it's tacky, use your fingertip to create a bit of 'texture" along the surfaces...Ease the jugs onto the engine case and bolt em' down.

Oh yeah, always replace the little O rings around the top studs, and either replace the pushrod tube seals or clean and inspect. Always apply a thin film of silicon grease inside and outside the seals before installation.

RDG

yes, I meant bases.

I may try the permatex...but later. Today I'm just going to try the original o-ring...minus the sealant.

BoxerTwin wrote:I had a decent weep coming from the base of my cylinder head.

I too have almost wept after seeing oil at the barrel base. Get over it.

I would use a sealant as well an o ring.
I forget which brand of sealant I used on my barrels, but I do have Permatex aviation gasket stuff. It's good on valve covers too, it's non hardening so the covers come off easily.
I like the idea of using Permatex on the barrel bases.

I think general consensus here is, use a good sealant.

I shouldn't have said a weep, it was downright crying. There was a small oil puddle at the top of the head where the oil was coming out; nearly bubbling out when riding.

I put it all back together without sealer and with the o-ring. If it leaks too bad, I'll redo it.

If my valves were properly adjusted before I disassembled it all, do I need to readjust them on the reassembly?

BoxerTwin wrote:If my valves were properly adjusted before I disassembled it all, do I need to readjust them on the reassembly?

Did you get the assembly back together EXACTLY as before the work? Is this your lucky day, is it??

It takes only a few minutes...I'd quickly check it, for peace of mind. You'll need to recheck in several hundred miles as well.

Kurt in S.A.

Kurt in S.A. wrote:

BoxerTwin wrote:If my valves were properly adjusted before I disassembled it all, do I need to readjust them on the reassembly?

Did you get the assembly back together EXACTLY as before the work? Is this your lucky day, is it??

It takes only a few minutes...I'd quickly check it, for peace of mind. You'll need to recheck in several hundred miles as well.

Kurt in S.A.

I saw BoxerTwin's tongue sticking through his cheek.

justoneoftheguys wrote:I saw BoxerTwin's tongue sticking through his cheek.

I guess I wasn't squinting hard enough to see that!

Kurt in S.A.