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Valve Cover oil leak

salty_monk

salty_monk

Forum Guru
Past Site Supporter
TGSR Superstar
Well I finished adjusting valves... not a huge change but power delivery seems better & slightly smoother than before. Any way I'm happy. Got them all 0.06 to 0.08.

I fitted a Real Gaskets silicone gasket to the valve cover & new half moons. Now I have a small oil leak, looks to be coming out of 1 side end cap.

Need to investigate more.

Do Real Gaskets "wear in" (i.e. leak a bit then seal up?) I doubt it.

Did I torque it too tight or loose? I basically got a socket wrench & did them up until the ratchet action started to work (roughly hand tight, it was flat, not pinching) & then turned them about a 1/2 turn more. When I looked some are slightly pinching you can see about 10-20 thou deformation on the gasket.

I pushed the new half moons down with a screw driver when I fitted them.... now I'm thinking maybe I should have fitted the cover & tried to torque it down without a gasket first to make sure they were flat... could that be the problem? The torque I've used isn't enough to level them out?? Can I torque it tight now & then back it off with this gasket?

The Real Gasket has quite an overhang at the end, the chrome caps bend it at the corners... don't see this being an issue though...

Anyone want to give me the benefit of their experience?

It's not a big leak but enough to notice 2nd time out (sitting on the fins).

Thanks,

Dan :)
 
half moons

half moons

If you noticed, the new half moons were slightly higher than the rim when you put them in. The reason for that is so that they will be slightly compressed (and seal) when you install the valve cover. My guess is that they weren't sufficiently compressed using the Real Gasket.

The old ones would have been conformed and flat upon inspection....but the new ones are new and stand slightly higher. New half moons work well with a OEM or Vesrah (or any standard) gasket but maybe not so well with the Real Gasket since it calls (demands) less torque down.

I'm sure someone else has been through this since lots of the guys use the Real Gasket....you'll no doubt get some good advice on how to deal with it.
 
That's what I feared. I nearly didn't change the moons because the old 'uns looked ok.... Then I figured well I got them so......

Perhaps I should have torqued down the cover by itself first. I think I still have the old moons but not sure if that will help now I pulled them out. They were pretty well lodged in place.

I was pretty careful with surface prep too. Cleaned them both up with solvent etc. Guess that will be contaminated now too. Oh well....

Starting to think I should have just bought a $6 gasket from Z1!! :lol:

The new tacho seal stopped that little leak though :D

Dan :)
 
Information that I have says that Realgasket valve cover gasket torque is 15 INCH pounds. Very light.

From your description it sounds like you may have too much torque applied to that gasket.
 
Not!

Not!

That may be so for Real Gasket but the deal is that those half moons are manufactured to go with the OEM gasket and the foot pounds are 6.5-7.0 ft/lbs....

I thought about ordering one of those..but I didn't. There's an old guy in my town that works on old Jap bikes and he always uses OEM stuff. I'm old...and so did I.
 
mark said:
Information that I have says that Realgasket valve cover gasket torque is 15 INCH pounds. Very light.

From your description it sounds like you may have too much torque applied to that gasket.
Click to expand...

Not if the deformation of the new half moon wasn't sufficient to seal it...and it sounds like it wasn't! That half-round fills a spot that needs to be sealed and by pressing down on the flat spot, that takes place. The old ones are pretty well set and if you don't mess with them, they won't usually leak. If you change them out and don't compress them, you're asking for trouble.:-s
 
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I've read that some put the end seals in backwards (lip to inside). So that's what I did after my rebuild. I first used a stock type gasket but have switched to a Realgasket. So far no leaks.

My recomendation would be to pull the cover, clean everything with solvent, reverse the end plugs, torque the cover without the gasket (to seat the plugs), then add the gasket.

One thing to check though, will the cover tighten down without hitting the cam chain on cam blocks if the gasket is left out.
Buddy
 
chuckycheese said:
That may be so for Real Gasket but the deal is that those half moons are manufactured to go with the OEM gasket and the foot pounds are 6.5-7.0 ft/lbs....

I thought about ordering one of those..but I didn't. There's an old guy in my town that works on old Jap bikes and he always uses OEM stuff. I'm old...and so did I.
Click to expand...

I always use OEM as well. I'm old too.
 
Don't torque that RealGasket too much! You'll pinch it and cut through. Doesn't take much. Ask me how I know...

Hand tight plus .5 turn is perfect. Actually you'll have to go around several times 'cause with that squishy gasket tightening bolts causes others to really loosen, but you get the idea.

What you want to do instead is use a bit of RTV on the half-moons. Even the anti-RTV nazis here suggest that, I think. ;-) Never had a leak doing it that way.
 
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I used RTV with old moons and one popped out on the highway. Covered my boot and pants with oil but it got me home. Just push the moons down hard with your thumb. I use silicone gasket on both bikes and it works well.
 
well I thought i already did the pushing & if the lip on the moons is meant to be on the outside then they were & are already fitted backwards (its on the inside...)

Damn new technology..... To be honest I would have left both well alone without added info. Left them in & OEM all the way.

I guess I'll have to take the tank off again & go play... what;s RTF?

Dan :)
 
RTF = silicone gasket maker stuff

I used the orange (copper) colored stuff on the half moon seals but left the gasket dry. Just need a thin coat.
 
t3rmin said:
RTF = silicone gasket maker stuff

I used the orange (copper) colored stuff on the half moon seals but left the gasket dry. Just need a thin coat.
Click to expand...

It's RTV, actually. Room Temperature Vulcanizing.
 
Yes, what he said, not Rich Text Format, as was apparently floating around my head (I did get it right in my first post at least!). ;-)
 
You can always try using a light application of high temperature silicon to the half moons to ensure they seal in properly.
 
Thanks for all the help guys. Will try to find some RTV soon & give it a go. The old ones had some orange gunk on them & were in pretty tight so that's possibly what it was.

Anyhow the leak is not a huge one but it is going to dirty up the engine a bit.

I think I might try fitting the cover without the gasket whilst the RTV dries, make sure they are in there good & tight.

I'll clean it all up & refit the silicone gasket dry.

If i'd only left the old moons alone!! :lol: Oh well, easy in hindsight....

Dan :)
 
Dan, I used new half moons, installed with the lip in, a RealGasket, and NO GASKET SEALANT whatsoever. I listened to the Guru's here. I had zero problems with the install, and no leaks.

I'd try to resolve this challenge soon if I were you. You have a long road trip comming up soon. We can't have that leak getting any worse, now can we?
 
I have Dan's problem on my '79 850 at 2 end plugs. The half moon plug wants to sit up just a bit from the gasket surface with the light Realgasket torque. The cure, I think, is to lightly use Ultra Gray sealant to just level the area on both sides of the half moon to the head's gasket surface. The light torque on the Realgasket will not allow the Realgasket to fill in that small triangle of clearance on either side of the plug. The sealant does the job.

I have not done mine yet because the leak is insignificant, but I'll get to it in time.

Tomcat 24551
 
The moons definitely "sit up" before the cover was first fitted. I'll report back if I find the cure....

Tom - I'm on it :D

Dan :)
 
Well it seems the gasket to moon interface is not the problem, appears to be coming from the bottom of just one moon where it sits down into the casting.
I seem to remember the old ones having some gunk is this area so I going to give it a go & report back... might be lucky & not have to take the tank & cover off again....

Dan :)
 
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