Persistent oil leak from camshaft seal

[levdir]

So, a while ago I had a tappet locknut work itself loose and fall into the valvetrain oil galleries, which necessitated removing the valve cover to get at it. Ever since I've had an oil leak from around the camshaft seal. I replaced the seal with a NOS Yamaha part but the leak continued. I discovered that the 10mm bolts on either side of the seal had stretched and replaced them. It's still leaking. Each time I pulled the valve cover I cleaned both surfaces thoroughly and applied Permatex gasket maker (can't find Yamabond to save my life for some reason). Any thoughts?

 

[Lou Ranger]

Maybe a combination paper gasket with added Permatex?
Assuming you could accurately cut one out of gasket paper or a corn flakes box.

Is there an irregularity in the surfaces being sealed together?

 

[arfstrom]

http://www.xs400.com/forum/showthread.php?t=11668
That link is some PDF's. There are a couple more sources on our site here. I just did one for the stator housing, that could be printed to a paper, then templated out. Like the Rugg... suggested, do a test print, print to actual size, then double check. Rug... pointed a size adj that works if your printing from Internet explorer. (I haven't seen chrome do that yet) double check with the ruler that I put there. I figured it is good to have a bases for examining. both inches and mm.

Ever since I've had an oil leak from around the camshaft seal.

Is that under the ignition pickup, there is a round seal there? there is two rubber boots there, could they be leaking?

 

[levdir]

Lou: I could try that. At this point I'm pretty fed up with pulling the camshaft cover every time I try to solve this. As for imperfections, I'm not sure. Nothing glaringly obvious and I cleaned both surfaces carefully every time. Oil isn't leaking from anywhere except out of the vents in the TCI cover, which means it has to be coming from somewhere right around the camshaft seal.

Tobie: Could well be. They're both present and they both fit snugly, but I haven't inspected them closely. I think I recall hearing that they aren't available new anymore?

For the record on my test ride last night after I replaced the stretched bolts (snapped one off in the bolthole, had to pull the valve cover again to get the broken end out) the oil leak seemed reduced. It might be that the Permatex hadn't fully set up; I let it sit for most of an hour before I tightened the bolts down completely but I think it needs a full day to fully cure. I've gotta resync my carbs because I replaced a missing idle air screw so I'm going to torque the bolts down again while I have the tank off. I guess I'll see.

 

[xschris]

The oil is coming from the rubber plugs that hold the rocker shafts in. Put a little high temp sealant around the before you put them in. It should stop any oil from getting arounf them.

 

[levdir]

Great, thanks Chris. I'll do that ASAP. Really looking forward to being able to park on the side stand again.

 

[arfstrom]

I have oil leaking around the round seal, that goes around the pickup. is that the same solution? From the pic's, it seems I should be able to coat the back of the camshaft/pickup seal.

Tobie

 

[arfstrom]

levdir, Did you pull your engine out to do the top of the head? You were able to do it with out much trouble?

I think that will be my next check for that infernal chirping noise.

 

[levdir]

I haven't had to pull the engine, you can reach all the bolts with the engine in the frame. The manual has the correct order but basically you just remove the six 10mm bolts in the middle first, then the inner four 12mm bolts, then the four 12mm bolts on the corner. Make sure to make note of which bolts came from where because they're not all the same length.

Also be careful putting it back with fresh RTF on it. The only thing you have to do is remove the upper engine mount and the tachometer cable. Yamaha, in their infinite wisdom, used a Phillips screw to retain the cable and it strips pretty easily, so mine is now a slot-head until I get around to replacing hardware this winter.

 

[Lou Ranger]

... Yamaha, in their infinite wisdom, used a Phillips screw to retain the cable and it strips pretty easily, so mine is now a slot-head until I get around to replacing hardware this winter.

Phillips wrecks a JIS every time unless you file it down. Then it takes longer to wreck one.
A good thread:

http://www.xs400.com/forum/showthread.php?t=9082
​

 

[levdir]

Aha! So these screws are just extra-stupid. Got it. I'm replacing everything I possibly can with hex heads as soon as the bike's parked for the winter.

 

[levdir]

I took Chris's advice and sealed the rocker shaft plugs with Ultra Copper, but I did it at my friend's garage and had to ride home on barely-cured sealant, and lo and behold, it leaked again. I assumed it was due to seepage occurring before it could cure properly and ruining the seal, so I parked the bike overnight, pulled the plugs, cleaned them up as best I could, and applied new sealant. I let it sit for a full 24 hours to allow proper curing and went for a very chilly ride tonight. The damned thing is still leaking, and I'm out of ideas. I can't park it on the sidestand because it leaks nonstop until the oil galleries are dry, and I can't make any plans to clean up or paint engine parts because the entire left side of the engine is coated in oil and will continue to be until this leak is solved. The camshaft seal is new, as above. The valve cover sealant does not seem to be leaking at all. Any suggestions?

 

[Lou Ranger]

I'm not good at translating things like a pic of the inside into an understanding of how oil comes out of the assembled engine - only when on the side stand.
But simply looking at the black plug in Chris' pic, I think I see a couple of '0' rings. If that's what they are, any chance you could replace with same diameter rings but a larger gauge?

If not, what holds the plugs tight in place? If it is the side case which does so when it's bolted on, is there a chance that the gasket for the casing is thicker than original, thus not letting the casing press against the plug to hold it tight? If so, could you put a dab of Ultra onto the part of the plug that the case presses against to make up the difference?
I may be completely wrong about how it all works, but you did ask for suggestions from a group, the majority of which, doesn't know very much ...

 

[xschris]

The point cover on a non-point bike uses no gasket. Those plugs are the o-ring. Only the other side uses them. The rocker shaft area holds very little oil when the bike is off. Only oil pressure when it is running, also being well above the cam oil baths. The cam seal is the only area where oil could come out on the side stand.

 

[Lou Ranger]

See, I told you I may be completely wrong. Thanks Chris.

Not sure I can understand it any better though.
It's a good thing that, while in the minority, there are still enough folks like Chris who can help the rest of us out.

 

[levdir]

Is it possible that the replacement cam seal I got dried out somewhere along the line and isn't sealing effectively? I can guarantee that it's seated properly, I hammered it into its seat with a socket and a rubber mallet after the valve cover was finger tight last time I had it off. As above, it's NOS Yamaha but it was delivered loose in a little baggie, so who knows where it was before then. All the seal kits I've seen on eBay have been heat-sealed.

 

[xschris]

The best way to put the seal in is with the cover off. That way when you put the cover on it is already lined up. Then all you have to do is tighten up the cover it will be pressed into place.

 

[levdir]

That's what I did, I just hammered it down to be completely sure. The first time I pulled my valve cover the original cam seal (the one that's since been replaced) looked like it was seated correctly but got knocked out of place when I put the cover back (engine in the frame) and wasn't sealing at all. I didn't pull the TCI unit that time so I didn't notice until it started weeping oil. When I put the replacement one in I hammered it down for extra certainty. That leaves my question: could a NOS part have dried out or otherwise failed on the shelf, causing this leak? I can't think of any other possibility at this point and I'm tired of fruitlessly cleaning oil off my engine.

 

[xschris]

I have used a N.O.S seal cam seal in my 80 with no issues. I guess it could have gone bad but I would think hitting it with a hammer may have caused it to deform or twisted it a little. It would not take much to get it to loose contact with the cam and break the seal.

 

[levdir]

To be clear, I did not pound it into oblivion. I just used a large impact socket to apply even pressure to the flat upper surface of the seal with a rubber mallet (after it was already in the race and after the valve cover was finger-tight) and tapped it into its seat to be certain it was flush. I cannot imagine how that would have damaged it.