Head Gasket

[bikeymikey748]

First the bad news: I could live no longer with my small but persistent oil leak. Astute readers will recall an oil leak I dealt with immediately after my initial rebuild. At that time, galling on the heads and the copper head-nut washers were to blame. I had wet-sanded the washers and applied a smear of seal packing on them, before torquing everything back to spec.
It worked
For a time
I was forever dealing with a slight 'sweat' of oil on the L.H. cylinder.
As the forecast was for 'Crap' today, with scattered ' Crap' tomorrow, and my new head gasket had made it here, I took the opportunity to dive in





Here's a shot of the damaged area, immediately under the head nut washers ( all 16 surfaces were in similar or worse condition. The surface immediately to the left has had an initial pass of grinding compound). The two outer 8mm. studs, on the LH don't matter in this regard. The LH side of the head drains it's oil down their enclosed passages. It doesn't matter if the copper washers don't seal entirely.



I set things up on my drill press. Using a flanged bolt with the same circumference as the washers, and valve grind paste I cut the galled areas down just as much as needed. The cam caps will sit on very slightly less material, but I don't imagine it being an issue, over the leaking concerns.



I'll wet-sand the washers again, and that should do it.
More good news ? My cylinders look über minty, very even wear and nice cross-hatch still visible. And....my valves are all sealing better than they were when I checked them during the original build (something like 15,000km. ago).
Now, if the weather would just start cooperating in a few days.........

[cbx6ss]

Did this solve the leak?

[bikeymikey748]

I'll let you know in a few days. So far, I've only just let it idle for prolonged periods ( it seems 'minty'), the weather has been less than cooperative.
Tomorrow is looking good for a romp.

[bikeymikey748]

Well, 500km. later, the short answer is....nope
Actually, the studs are still dry, as was expected. But, the tiny 'sweat' on the LH edge of the block ( at the head gasket) still mocks my efforts
The, supplied, head gasket with the Cruising Image kit was a composite with a graphite coating. I don't recall if it had rubberized treatments at the chain cavity & LH oil returns, but if it didn't I would have applied Toyota sealant. All this to say that I was surprised to have gotten the original sweat, the stud/washer issues notwithstanding.
The gasket I just put on, from Tim's, was a Cometic item. It lacked the graphite, and the surface seemed very absorbent. I treated it with a product I've had excellent results from in the past. I did everything the same as always. The cylinders were 'decked' when bored, the head was in good shape, though I never checked with a straight edge.



Oil just seems to 'weep' from the head gasket at the end of the day. Just a few, small, drops really, nothing most folks couldn't live with. But that sort of thing drives me crazy.
There's a lot of rides coming up, and don't have the time/patience to go in again.
Man, just a depressing day.

[manxman]

Hi,
Did you anneal the copper washers before re-use. This would greatly improve their ability to seal. I think this is why they are made of copper.
Dave.

[daves79x]

Your elaborate polishing of the sealing washer surface would only stop oil from running down the threads of the studs. That really has nothing to do with head gasket sealing. Where yours is leaking is something else, like an imperfection in the head or block or something else. I've rebuilt, or had the heads off dozens of CBXs and never polished the washer sealing surface or annealed the copper washers and I've never had a leak anywhere. Got to be something going on with that side of the head or block.

Dave

[bikeymikey748]

Yup, Dave. The initial leak, and 'leak' it was, came from the studs shortly after the first start-up. The washers & their seats on the head never had a chance to seal, they were so badly gouged. They are not the problem any longer. And yes,the washers were annealed.
My cylinder block was decked when the rebore was done, but I've never laid a straightedge along the head. It's, really, not leaking. More like an annoying 'sweat' that appears at the end of a long day. Likely, I'll be getting the head machined too, this winter. As it is, a thin bead if sealant along the LH head/cylinder joint (can't see it really) is enough to keep things dry. Happily, the oil never seems to migrate to the #1cylinder. Too much material and the metal crush ring around the bore saving the day, I'll wager.
Kinda frustrating all the same.

Your elaborate polishing of the sealing washer....

Ya, that's just how I roll. Can't help myself from going over the top, most times

[bikeymikey748]

Well, 400km. Yesterday ( check vid clip ), and....I now have a leak. It's worse than it was. Maybe I'm not prepping the Cometic gasket properly. Anyone have experience with them ?
A new one is inbound from Cruzinimage. It's more a match for the OEM item, but again, I don't recall how the cam chain opening & oil return areas are/should be prepped. This gasket has the graphite finish that I don't believe can be trusted, on its own, to seal those areas, even given that it will bond to the alloy surfaces. Generally, I recall those areas have a rubberized treatment to better seal against the oil. I find it odd that 'O' rings aren't used on the two LH outer stud openings.
I'm kinda bummed that I have to do this AGAIN, but it's got to be done correctly. I WILL check with a straight edge, though the fact the gasket has failed so quickly leads me to believe it's an installing issue on my part.
There's a BUNCH of, once a year, rides/rallies coming up, I sure hope this won't cause me to miss out on any

[daves79x]

Sorry you've got to take it apart again. I don't think it's the gasket or your prep. I've used OEM, Cometic, copper, and never had a leak. No special prep except cleaning all the old gasket off, as you would anywhere. Since you're absolutely positive its coming from the head gasket area, there must be an imperfection or something compromising the sealing surface. The head gaskets are made to install dry and there's no secret to it.

Are you sure your studs are torqueing to the proper value? These studs have a tendency to 'pull' out of the case very slowly, not permitting full torque to be applied to the cap nut. With your attention to detail, I'm sure you'd have noticed that.

Otherwise, these things just do not have head gasket leaks, so you should find something obvious.

Dave

[bikeymikey748]

Thanks for the input, Dave.
Yup, all the cylinder studs were assembled with Loctite blue. They're securely in place. Torque feeds into them at a uniform rate.
I ordered the gasket last night. There was a screw-up in my asking for it to be express posted. It'll likely be, at least, two weeks before I see it.
Meanwhile, I have no confidence in putting any decent mileage on the bike, and Americade is two weeks away. I head down for the last Saturday and make a day, 5-600km. of it. It's looking bleak

[EMS]

I don't think either that it is a gasket or prep issue. But for what it is worth: I spray all head gaskets that I install generously with a copper spray. As Dave said, you must have some imperfection or fault somewhere in the head or the low end surface which prevents proper sealing

[daves79x]

Just to be clear - studs will pull the threads right out of the block. These blocks have very porous castings and I've fixed a number of these, but mostly main cap bolt threads that have very few 'threads' from the factory and won't torque.

But you would 'feel' this when torqueing the head.

Dave

[ericfreeman]

I'd use a machinists straight edge to see if I could spot any surface imperfection causing your leak. As others have said, certainly sounds more like a flaw in the head/block interface than your installation technique.

Eric

[bikeymikey748]

Well, guess I should have had a bit more faith in the Japanese postal service. I got my gasket yesterday at lunch. How excellent is that ?!
Got the head off, again, and things were as expected The Cometic gasket, even with a generous application of gasket sealer, had soaked through in the area of the outer LH studs. It was letting oil pass to the outside of the block. Look at the photo. In places it had bonded, as you would expect, and had torn when the head and cylinders had been separated. In other spots, notably the LH outer stud area, it didn't adhere whatsoever. The photo is of the, failed, Cometic and the Cruizinimage replacement . The Cruizinimage bit has a more OEM make up.


All surfaces were checked with a straight edge, no warping/irregularities whatsoever.
Here's a pic of a Yamaha XS650 head gasket. Notice the application of rubberized sealant in the area of the cam chain tunnel. This is what I'm used to seeing on head gaskets for air-cooled motors.


I put a smear of sealant in similar areas on the 'X', as well as in the area of the LH stud/oil drains. We'll know in short order how she works out. Three time's the charm, right ?

[bikeymikey748]

700km. (430mi.) down and back to Lake George for the last day of Americade, yesterday. I rolled out at 6:00 and got in at 17:15.
The bike ran like a champ. And, I am happy to report....ZERO leaks !!!!
Time to ride the wheels off this bad boy!