GS850GZ cylinder head oil leak

[Tool]

Did a forum search on this problem and couldn't see anything that quite matches, so here goes........feedback would be much appreciated.....

The 850 has developed an oil leak which is pooling around #3 plug and spreading around in the airflow from there. It's not the tacho drive (been there- done that), or the cover gasket (all dry up there), or the cam end caps, or the cylinder head gasket. It appears to be down in the top of the head somewhere.

It looks like a head bolt which doesn't make sense as they're all torqued to spec. Any o-rings buried in there? Unfortunately the leak isn't fast enough to provoke in the workshop and by the time it's happened on a ride the oil has spread enough to mask the source.

Oil leaks are annoying.

[bwringer]

The only other possibilities in that area are the acorn style nuts with copper washers under them.

At least they're supposed to be acorn style nuts. And they're supposed to have copper washers under them...

They are parts number 12 and 13 on this diagram:

http://bwringer.com/mc/19080gs850head.gif

Parts 14 and 15 are plain old nuts and washers.

You can reach them easily without taking anything apart, so you might as well check the torque on them and make sure the copper washers are in place.

The studs that these nuts go onto are narrower below a short threaded section so that they act as the oil passages up to the valvetrain. Or back from the valvetrain. Anyway, whichever direction the oil goes, they are oil passages, so they will leak impressively if the copper washers aren't there or aren't torqued down.

Let me know if you need torque specs. I need to start keeping the motorcycle manuals next to the computer.

[bwringer]

Whoops, sorry -- forgot that you had already checked torque.

If it's the copper washers, it sure seems that you would get oil around #4 or #1 instead of #3, although with airflow blowing things around who knows.

The breather cover on top of the valve cover also springs to mind -- maybe the hose is split, or it's loose or the gasket is damaged. But that should leave evidence on the valve cover.

Maybe one of the sealing surfaces for the valve cover gasket is nicked in that area?

But there aren't any other seals hidden in there. Some other GS models have a tricky o-ringed nut, but not the 850. Above the head gasket, the only oil seals are the valve cover gasket, the breather cover, the tacho drive (2 seals, #21 and #22 on the diagram), the cam end plugs, and those copper washers.

[Tool]

But there aren't any other seals hidden in there. Some other GS models have a tricky o-ringed nut, but not the 850. Above the head gasket, the only oil seals are the valve cover gasket, the breather cover, the tacho drive (2 seals, #21 and #22 on the diagram), the cam end plugs, and those copper washers.

Ah, so there isn't the extra o-ring on the 850. Thanks. I'll stop looking.

There's no oil above the plugs. It's just got to be leaking from a head nut somewhere in there. Perhaps a split copper washer.

[bwringer]

It can't hurt to have a look at those copper washers.

They seem to be the same as the ones used in brake systems, so maybe you can locate a replacement without special ordering from Suzuki. I've also seen copper washers available for sealing oil drain plugs.

I've re-used my old ones twice with no ill effects.

[Tool]

But there aren't any other seals hidden in there. Some other GS models have a tricky o-ringed nut, but not the 850. Above the head gasket, the only oil seals are the valve cover gasket, the breather cover, the tacho drive (2 seals, #21 and #22 on the diagram), the cam end plugs, and those copper washers.

Ah, so there isn't the extra o-ring on the 850. Thanks. I'll stop looking.

There's no oil above the plugs. It's just got to be leaking from a head nut somewhere in there. Perhaps a split copper washer.

Two hours squatting (man, that hurts) beside the running engine with a strong work light has proved me wrong.

The oil is coming from the valve cover gasket and running neatly down an edge behind #3 plug - pooling and spreading out & down from the area around the base of the plug.

It only leaks to any extent with a warm engine. I got nowhere checking cold or hot.

Thanks for listening and the advice.

cheers