oil bubbling from top cylinder head nut

[user11235813]

This is probably no big deal but it's the first I've seen of it. Oil, valve check and head retorque yesterday to 29ft/lbs All the bolts had tightened up a fair bit, loosened them all in 3 stages and tightened up to spec in three stages in the order marked on the cylinder head. Today, I gave the bike a wash with some degreaser around the front of engine nothing near the head. After going for a dry off ride when I came back I see a bit of oil on one of the fins then I notice some oil bubbling around this one single head nut. I made a video. Funny thing is that usually after degreasing the front of engine, (not that there's much oil there, I just like to keep it clean) I get a bit of oil seepage around the bottom of the head for a day or so, which goes away as per photo marked in orange. But this time there was no oil seepage at all as you can see. Just this oil bubbling around the nut.

[sledge]

The clearance between the four outer studs and the cylinder block is used as an oil gallery. Its how oil reaches the top end and the cams and buckets. Underneath the nuts are one-shot copper sealing washers, much like the one on the sump plug. Their purpose is to prevent pressurised oil from leaking out of the top of the stud. The washers should ideally be replaced every time the nuts are removed. You have reused them and now one has lost the ability to make a seal and failed, I suggest you replace all 8 of the washers ASAP.

It's not uncommon to see this happen. The GS5 should have the head nuts retourqed on its shakedown service at 600 miles. When it doesn't happen it leads to leaks under the nuts and from the base gasket as the bike ages. When I was regularly buying and selling GS5s I would see it on a regular basis and use it as a way to get the seller to drop the price along with another common issue, seized or rounded out header bolts.

[alpo]

Great input - thank you! 

[user11235813]

thx Sledge, I wiped it dry and took it for a hard ride, and it seemed to stay dry but there may be a very very small amount of oil seepage, hard to know if I'm imagining it. Anyhoo, I was wondering why you suggest all 8 washers and not just the four outer ones? I'd be paranoid of doing the inner ones in case I drop a washer into the engine.

The clearance between the four outer studs and the cylinder block is used as an oil gallery. Its how oil reaches the top end and the cams and buckets. Underneath the nuts are one-shot copper sealing washers, much like the one on the sump plug. Their purpose is to prevent pressurised oil from leaking out of the top of the stud. The washers should ideally be replaced every time the nuts are removed. You have reused them and now one has lost the ability to make a seal and failed, I suggest you replace all 8 of the washers ASAP.

It's not uncommon to see this happen. The GS5 should have the head nuts retourqed on its shakedown service at 600 miles. When it doesn't happen it leads to leaks under the nuts and from the base gasket as the bike ages. When I was regularly buying and selling GS5s I would see it on a regular basis and use it as a way to get the seller to drop the price along with another common issue, seized or rounded out header bolts.

[sledge]

I would replace all at the same time because it's good practice to 

Unlikely that you will drop anything down the camchain tunnel, you won't be removing the head!

[user11235813]

OK, so what is the correct procedure here this is what I'm guessing...

Back all head bolts off in sequence in stages to a low torque, then replace washer one at a time sequentially to low torque, then torque them all in order in two stages?

I'm assuming that it's not a good idea to back off all the nuts to no torque at one time due to the head gasket not resealing properly. Or is this not a problem.

Next question is that the inner 4 bolts will have oil on them and the outer 4 will be dry so how does that affect the torque? I'm given to understand that oil on the threads could mean they torque up more or is this not anything to worry about.

Then once this is done does it mean that a retorque will be needed at 1000kms again due to the washers being new as if it was a new bike?

[sledge]

Sounds fine to me, just make sure the threads are clean and dry, a retourqe won't do any harm when everything has cycled a few times.

[Bluesmudge]

If it was me I would just replace the one copper washer and be done with it but I like to make things easy. What is the advantage of replacing all of them preemptively?
If I remember correctly, Suzuki recommends loosening and re-torquing the head bolts every 4,000 miles. They doesn't make any mention of replacing the copper washers each time you re-torque. I would only replace them if you are removing the head or if you are getting leaks.

[J_Walker]

you're telling me, GS's aren't suppose to weep oil around the CC marking plate of the engine?! HAH. yeah right... I've seen MINT [4k miles] GS's with that issue. its kinda funny actually.