Topic: Oil bubbling out between head stud and nut

[dunnp2]

Hey all, I've been searching about this one for a while but it's hard to wade through all the failed o-ring oil leak threads. I don't see anyone posting about this issue.

My CB550F is leaking oil (and bubbles, I can watch them after I finish a ride) between the threads on the head stud to the right-rear side of the #4 cylinder, down in the spark plug cavity. Maybe also the stud next to the spark plug in front. I think also on the left of #1...

I've seen mentions of thread sealant in a few threads, is this what people are talking about? Which end of the stud should I apply sealant to? Can I break one nut loose at a time to do the job or will I need to do a full head gasket replacement to do it properly?

If thread sealant isn't the fix, what is? Thanks in advance.

[754]

Did you check the torque ?

[dunnp2]

Did you check the torque ?

Yep, they're tight. Didn't get a torque wrench out but it seems 'head stud' tight to me.

[bryanj]

There is no oil anywhere near those studs unless you missed out the O ring in the end of the head gasket. Could it be dribbling down from the bolt holding the bracket behind the end cap, there is supposed to be a sealing washer between the bracket and the cam cover

[Alan F.]

Did you check the torque ?

Then break out a good torque wrench and make sure.
This isn't something to overlook.

[dunnp2]

There is no oil anywhere near those studs unless you missed out the O ring in the end of the head gasket. Could it be dribbling down from the bolt holding the bracket behind the end cap, there is supposed to be a sealing washer between the bracket and the cam cover

This is what I suspected as well. I replaced the o-rings in the end caps and the aluminum (I used copper) washers sealing the brackets. No change. The end caps are clean and dry.

I can watch bubbles come up between the threads and see the oil pool grow in size on top of the nut. I'm certain it's coming from there.

The head gasket was supposedly replaced by the PO 'recently' so I guess it's likely that they missed that o-ring and I have to take it all back apart. In that case I'll ride it through the summer and do the job in the winter.

It is a pretty significant leak though, so I might give loctite 572 a try anyways. Worst case I need to replace the head gasket and I'm back where I started.

Did you check the torque ?

Then break out a good torque wrench and make sure.
This isn't something to overlook.

I'll double check with a torque wrench before I do anything else. For anyone else looking at this, the manual says the torque should be 14.46~16.63 ft-lbs. (2.0~2.2 kg-m)

Thanks for the replies!

[HondaMan]

Here's the "rest of the story" (thank you Paul, RIP...):
All of today's head gaskets are too thick. When asbestos was outlawed in the 1990s for automotive use, these head gaskets went from [average] 0.8mm thick to 1.0mm thick. The O-rings (and other sealing devices) in the head gaskets MUST ALSO be made thicker, or it WILL leak. The only other alternative is to mill the 0.2mm thickness off the cylinder deck, and I usually do BOTH when rebuilding these engines, because the compression comes out lower by a couple of tenths of a number from the thicker head gasket, all else being equal.
In the 750, this makes the oil passage O-rings in the head gasket to 2.6mm thick: in the 500/550 I use 3.0mm thick.

[calj737]

Here's the "rest of the story" (thank you Paul, RIP...):
All of today's head gaskets are too thick. When asbestos was outlawed in the 1990s for automotive use, these head gaskets went from [average] 0.8mm thick to 1.0mm thick. The O-rings (and other sealing devices) in the head gaskets MUST ALSO be made thicker, or it WILL leak. The only other alternative is to mill the 0.2mm thickness off the cylinder deck, and I usually do BOTH when rebuilding these engines, because the compression comes out lower by a couple of tenths of a number from the thicker head gasket, all else being equal.
In the 750, this makes the oil passage O-rings in the head gasket to 2.6mm thick: in the 500/550 I use 3.0mm thick.

So how does that translate to weeping through a cylinder wall? Your assertion is the leak is from the seam, which is not the case 

I am dubious anyone manufacturers bulk rubber o-rings to a 0.008 consistency.

[scottly]

Here's the "rest of the story" (thank you Paul, RIP...):
All of today's head gaskets are too thick. When asbestos was outlawed in the 1990s for automotive use, these head gaskets went from [average] 0.8mm thick to 1.0mm thick. The O-rings (and other sealing devices) in the head gaskets MUST ALSO be made thicker, or it WILL leak. The only other alternative is to mill the 0.2mm thickness off the cylinder deck, and I usually do BOTH when rebuilding these engines, because the compression comes out lower by a couple of tenths of a number from the thicker head gasket, all else being equal.
In the 750, this makes the oil passage O-rings in the head gasket to 2.6mm thick: in the 500/550 I use 3.0mm thick.

So how does that translate to weeping through a cylinder wall? Your assertion is the leak is from the seam, which is not the case 

Who said anything about leaking through a cylinder wall???

[Don R]

 Acorn nut and copper washer until it gets cold out?

[calj737]

Here's the "rest of the story" (thank you Paul, RIP...):
All of today's head gaskets are too thick. When asbestos was outlawed in the 1990s for automotive use, these head gaskets went from [average] 0.8mm thick to 1.0mm thick. The O-rings (and other sealing devices) in the head gaskets MUST ALSO be made thicker, or it WILL leak. The only other alternative is to mill the 0.2mm thickness off the cylinder deck, and I usually do BOTH when rebuilding these engines, because the compression comes out lower by a couple of tenths of a number from the thicker head gasket, all else being equal.
In the 750, this makes the oil passage O-rings in the head gasket to 2.6mm thick: in the 500/550 I use 3.0mm thick.

So how does that translate to weeping through a cylinder wall? Your assertion is the leak is from the seam, which is not the case 

Who said anything about leaking through a cylinder wall???

yes, pardon me, wrong thread. Apologies.

[rotortiller]

Maybe try this and use hylomar sealant on the nut. https://www.amazon.ca/Earls-Plumbing-7-3120G-178006ERL-Stat-O-Seal/dp/B0012NSTIO

[bryanj]

Thing is no oil travels via the stud holes on 500/550 unlike the 750 so no matter what you do to cure it IT SHOULDNT BE THERE IN THE FIRST PLACE.

For oil to get to the stud hole there has to be a majour leak from an oilway to a stud and that needs to be found

[Alan F.]

Oh boy, has it been recommended to check the crankcase vent for obstructions?

[bryanj]

Oil level in crankcase is not high enough to be forced up the stud and even if it was it would still have to go via a gasket surface

[dunnp2]

Thing is no oil travels via the stud holes on 500/550 unlike the 750 so no matter what you do to cure it IT SHOULDNT BE THERE IN THE FIRST PLACE.

For oil to get to the stud hole there has to be a majour leak from an oilway to a stud and that needs to be found

Agreed, thanks. I'll need to do a teardown when winter comes.

Acorn nut and copper washer until it gets cold out?

That's a great idea! I have some loctite 572 on hand though so that's easier for me.

Oh boy, has it been recommended to check the crankcase vent for obstructions?

There is definitely air flow through the crankcase vent, it's not obstructed.

[dunnp2]

Quick follow-up, loctite on those nuts and both sides of the washers solved my issue. Clean and dry on my ride to work this morning.