rectangular o-ring problem?

[scottsgs]

Hi all,

When I recently put the head back on my 81 GS850G and torqued down the head nuts, I noticed that the rectangular o-ring has squished out of the gaps around the cam chain tunnel. I have tried two different o-rings and the same thing. Can some one explain this to me?

Thanks,

Scott

P.S. Thanks to Basscliff and MrSteve for the valve lapping info.

[Nessism]

Some head gaskets use the O-ring and others don't. Did the head gasket cover the O-ring groove? What brand of gaskets/O-ring did you use and what construction method for the head gasket (composite, MLS, ?).

[scottsgs]

I used MLS OEM head gasket and o-rings. Granted I re-used the head gasket because I just put it on a couple of months back. I don't see where re-use would cause this.

[Nessism]

I used MLS OEM head gasket and o-rings. Granted I re-used the head gasket because I just put it on a couple of months back. I don't see where re-use would cause this.

Did the gasket cover the O-ring groove? If so, I don't think you are supposed to use the O-ring.

[Macguyver]

Shiznizbiz and I were discussing a related o-ring quandry, and I believe unless you have a chain drive engine, the rectangular o-ring is not needed since the gasket takes it's place.

I could be wrong, but I think they package the master gasket kits to be able to be used for both the chain, and the shaft drive versions of the engine, and depending on your engine, you may have extras left over.

[Dogma]

Uh, Mac, the 850 only came in shaftie. If you look at the parts fiche for that bike, the cam chain tunnel o-ring is there.

I never looked to see if mine squished into the tunnel. Does it leak, or does the cam chain rub on it? The ones you tried, did they split from too much squish? Maybe it's not a problem.

[Buster-boy]

Scott, I just had this same issue just last week. I replaced my head and when I went to scrape off the old head gasket I saw the o-ring had jumped the groove and had been squished between the head and the cyls and was broken.

When I put the new o-ring on, I first lined that groove with a little bit of Vasoline, then set the o-ring in place. Worked like a charm!! That o-ring didn't budge an inch.

Be careful not to get any of it inside the cam chain chamber. Not that it would hurt the engine at all, but you simply don't need any more gook in your oil than you already have. Just rim it with a light coat and wipe off the excess. You'll be good to go.

Keep us posted as to how it turns out.

Been there done that!!
Jim

[DimitriT]

When I stripped down my 550 I noticed the original factory installed o-ring was held
in place by a coating of silicone rubber or such. I carefully dug every bit of that out
and put the new o-ring in without any sealer. 20k miles later I did a second strip down
and noticed that the o-ring had squished out of the groove. This may have explained
the seeping I noticed around the head. I reassembled but this time I used a little permatex
black to keep the o-ring from moving. 5k miles later and no more seeping.

[Macguyver]

Uh, Mac, the 850 only came in shaftie. If you look at the parts fiche for that bike, the cam chain tunnel o-ring is there.

That's why I put in "I may be wrong".

Thank you for correcting me Dogma!

[tkent02]

Uh, Mac, the 850 only came in shaftie.

The '77 - '79 750 had the same head and gaskets as the '79 850, the only difference in the 850s after 1980 is the intake port diameter for the CV carbs. So he could be right about the o ring.

[Buster-boy]

Yeah, if that o-ring doesn't seat correctly it'll seep oil out the back of the head near the chain tensioner. I only used the Vasoline to hold the o-ring in place while I mounted/torqued the head, not so much as a sealant. I didn't use Permatex because some of them are petrolium solvent and the oil will dissolve it over time. I've also found Permatex interfers with the gaskets sometimes causing a gap under the gasket, thus causing a leak. Permatex will accomplish the same thing as the Vasoline (heck, you could use peanut butter if you wanted to, but not the crunchy type - LOL), but will give that little extra sealant.

I think the problem with that o-ring jumping the groove is when I bought my new one it comes all crumpled up in the package and the middle of the long side of it is never straight. It tends to bend inward in the center, thus causing this problem.

Just my personal experiences.

Jim

[Macguyver]

I think the problem with that o-ring jumping the groove is when I bought my new one it comes all crumpled up in the package and the middle of the long side of it is never straight. It tends to bend inward in the center, thus causing this problem.

Whenever I had a slightly tweaked o-ring I would just set in in the sun for a couple of hours, or submerse it in a sink of hot water to get it to go back to proper shape.

I like the peanut butter idea, but would that cause the exhaust to smell like peanut butter? Might just make you hungry when you ride!

Kind of like the diesel cars retro-fitted to use deep fryer oil for fuel, a friend of mine did that to his Jetta, and it always smelled like french fries!

[scottsgs]

I used hylomar to hold it in place and that did work. So I am just gonna run it and see what happens.