Slash five head gasket leak

[Frog]

Hey guys/gals (or is that singular?):

I recently went for a little ride....to find my boots well oiled.

As it turns out, it appears that my head gaskets are leaking oil. The left more than the right....but the problem is getting worse fast. This has been happening for a while, but never enough to really care to find the source.

These head gaskets were changed about 6 years ago.

I recently switched to synthetic oil.

I plan to pull the juggs and reseal it all on Wednesday, as I also have a slight cylinder base weep on the right.

Any tips on this? Is this common? While in there, what should I measure/check out?

I will be riding this coming weekend, so will likely bring a torque wrench along and retorque at some point.

http://picasaweb.google.com/lh/photo/7G ... directlink

http://picasaweb.google.com/lh/photo/tX ... directlink

http://picasaweb.google.com/lh/photo/xK ... directlink

[mattcfish]

Be careful when checking the torque. The reason for the gasket and seal leaking could be because a cylinder stud is pulling out. Has the bike been bumped, dropped or over heated? I've owned my /6 for over 20 years and have never had a head gasket leak.

[gspd]

I recently switched to synthetic oil.

I think you answered your own question.
Synthetic has more of a tendency to leak out of older engines.

If your head bolts seem to loosen and always require re-torquing,
you're pulling the studs out of the block. (VERY COMMON)
If they don't feel rock solid at 30lbs, they're pulling out.
The only permanent fix is case savers.http://vw.efi.tech.free.fr/catalog/engine.pdf
scroll down to page 13

Beware: Common heli-coils may also eventually pull out. Case savers never pull out.

[Kurt in S.A.]

If they don't feel rock solid at 30lbs, they're pulling out.

Yikes! 30 ft-lbs on a /6?? Surely that's too much and will lead to the studs pulling out. My recommendation is to get to 25, maybe 26 but that's all.

Kurt in S.A.

[Deleted User 61]

Those must be Canadian pounds.

[Duane Ausherman]

Those gaskets just don't leak. There is more to the story, maybe the synthetic oil. Personally, I keep my head torque around 23 lbs. Hasn't leaked yet, but haven't started it in 3 years either.

[lrz]

Not to be dense,buuuut, I'm assuming those case savers come in various/appropriate size & thread pitch to re-use original studs then? Thankfully this is mere curiosity.

[SteveD]

I think I would clean it all up, change the oil back to dino and see if that helps.

If not, then I'd pull it down and do new seals, then add the synthetic.

[gspd]

Yikes! 30 ft-lbs on a /6?? Surely that's too much and will lead to the studs pulling out.

The functional difference between 25 and 30 is negligible.
If the studs pull out at 30, they were weak to begin with.
Solid studs won't pull out until way more than double that.
How much 'pulling out force' do you think those studs deal with during normal use? or racing?

We tried it years ago on a few scrap cases,
there always seemed to be at least one or two that pulled out like butter (way too easily).
The solid ones easily took over 60ft/lbs without budging.

It makes me chuckle when I see people re-torquing their heads when often all they are really doing is pulling the stud out a wee bit more each time. It's way more common than you think.

BTW -
Even the best torque wrenches are only certified to be within ±3% at half their scale.
The margin of error grows exponentially either side of the middle of their range.
A 0-150 torque wrench set at 25lbs can be as much as 20% off and still pass milspec certification.
To do it with the utmost accuracy (±3%), you need a 0-50 lb torque wrench (most are 3/8" drive).

Not to be dense,buuuut, I'm assuming those case savers come in various/appropriate size & thread pitch to re-use original studs then? Thankfully this is mere curiosity.

Ya, they have the right ones, you have to machine one tapered end flat.

[Kurt in S.A.]

gspd wrote "The solid ones easily took over 60ft/lbs without budging."

In all my years being around these bikes and reading what other people write about these bikes, I can honestly say I've never heard anyone mentioned a load anywhere near this. I really find that hard to believe. Why then did BMW limit the torque to 29-31 which I think was the highest for some years. If they can take double that, whey didn't they provide a range of say 30 to 40 and say that was good? Maybe we're talking apples-oranges. If 25 is good enough, why go any higher?? It just doesn't make sense.

I'm perfectly happy with my 0-150 ft-lbs wrench for use in appling 25 ft-lbs of torque for the head bolts. I calculated the amount of water in a bucket hanging on the end of my beam wrench to equal 25 ft-lbs. I read the wrench scale and know that if I hit that mark, I'm well within any kind of reasonable reading. Works for me.

Kurt in S.A.