Valve Cover Gasket Oil leak

[Nathan Daube]

My GS850GL with 45,000 has just started leaking oil from the left front side of the valve cover gasket. Last year I replaced the gasket and the 4 half moons under the gasket as well. Everything was great no leaks and ran great until about a week ago and its really leaking now. I should mention that I pulled the bike over on myself just before the leaking seems to have started, but I checked the cover bolts and they seem tight and I took off the cam covers and the half moons seem ok as well., although is looks to me like its leaking behind the cam covers. It drips out when the bike is running and runs out when you shut the bike off. Have a new gasket on the way but wondering what could be going on? Anyone have any ideas??

[bwringer]

Sometimes the gaskets slip out of position or the bolts loosen. In that case, the problem will be obvious when you pull the valve cover.

There have also been instances of valve covers developing cracks, especially if tightened excessively or unevenly.

Again, get the valve cover off and inspect carefully. A valve cover crack can be repaired.

[BassCliff]

Hi Mr. Nathan Daube,

Yes, clean the areas well, apply some kind of spray powder (like foot powder) and check for the wet spots. Are you sure it's not the tach drive gear area? The tach gear is famous for leaking as the seal wears. Is your breather hose clogged at the top of the airbox?

Thank you for your indulgence,

BassCliff

[feelergaugephil]

Use yamabond (buy at yamaha dealer) clean off all mating surfaces with alcohol, then use a thin layer of yamabond, use new gasket, and DONT tighten down the 10mm bolts too tight, also, if you want, lift up the half moons and run a small amout of yamabond under them.
GS's are prone to leaking, they remind me of the old Harleys at times!!!!!!!!!!!!!!!!

[Nathan Daube]

Yeah its leaking exactly like an old harley and has marked its spot in the garage in several locations. I replaces the tach seal last year so that isnt leaking and I did use the red permatex gasket sealant as well as a new gasket last year. Im hoping that its just as someone said a slipped gasket but not confident thats the problem. Im still waiting on Bike Bandit to ship the gasket as well as the rebuild kit for the rear master cylinder as it also failed the other day. Will let you know what I find out. Thanks everyone for the ideas, hoping its a clogged breather and a slipped seal but we will see.

[Nathan Daube]

Which way do the cam end plugs go on

Ok so I finally got the valve cover gasket and after taking everything apart I found that the gasket had slipped out of place at the cam end where the cam end plugs go. When I installed the plugs last year I installed them with the ridge to the outside on the cam end hole. I was looking at them closely today and they will also fit with the ridge on the inside (which I think might keep them in place better. SO the question of the day is, which way do they install??

[Colin Green]

Ok so I finally got the valve cover gasket and after taking everything apart I found that the gasket had slipped out of place at the cam end where the cam end plugs go. When I installed the plugs last year I installed them with the ridge to the outside on the cam end hole. I was looking at them closely today and they will also fit with the ridge on the inside (which I think might keep them in place better. SO the question of the day is, which way do they install??

I just did mine not an hour ago... Lol. Hope it doesn't leak.

Half moon seals go flat side out... though having them the other way might eliminate the occasional rattle caused by the cams floating from side to side and touching the cover. Don't know that I'd risk it without someone confirming that they have done so with success.... will you be that person??

[BassCliff]

Hi,

I haven't tried it yet, but several members have installed the half moons backwards with good results. Yes, it can quiet a cam float rattle. The half moons can't come out because of the ridge on the part itself. They can't fall into the motor because there's nowhere for them to go up against the cam shaft end.

I've never had an issue with my half moons leaking. I use a little gasket sealer on the curved part of the half moons. I do not put gasket sealer on the flat part of the half moons because I use a Real Gasket (reusable silicone) and I don't want anything to stick to the gasket, it goes on dry.

Thank you for your indulgence,

BassCliff

[Colin Green]

Hi,

I haven't tried it yet, but several members have installed the half moons backwards with good results. Yes, it can quiet a cam float rattle. The half moons can't come out because of the ridge on the part itself. They can't fall into the motor because there's nowhere for them to go up against the cam shaft end.

I've never had an issue with my half moons leaking. I use a little gasket sealer on the curved part of the half moons. I do not put gasket sealer on the flat part of the half moons because I use a Real Gasket (reusable silicone) and I don't want anything to stick to the gasket, it goes on dry.

Thank you for your indulgence,

BassCliff

Cheers. Saved link for next time