Major c**k up, help required!

[LewisB]

Not a great thing to find out before my birthday ride…

Oil coming from the cam cover, snapped bolt (I noticed it was loose and it pulled right out.

I need a plan of action to fix this. I’m abosultly gutted

[LewisB]

Crisis averted

[tony.mon]

So how did you stop drilling swarf from getting into the engine?

[Kev L]

Well done on getting the broken stud out mate

[Jamoi]

Good save!

Has it recently been worked on? Seems odd to have randomly sheared off.

[fabiostar]

Count that as a lucky escape

[sirch345]

The good thing about shearing one of those cam cover bolts is, due to the shoulder on the bolt it stops the thread tightening up like a normal stud does, meaning it stays lose in the threads of the cylinder head. They are easy to shear though. I have managed to undo a sheared one by unscrewing it enough with a small electrical flat blade screwdriver so you can grab it with a long nosed pliers to undo and remove. At least you got it out

As Tony says, what happened to the swarf?

Chris.

[LewisB]

So how did you stop drilling swarf from getting into the engine?

First I packed the crevices with rags, then when drilling, regularly dip the drill bit into grease, this will make the shavings and dust stick to the bit, clean the bit lots and wipe with a rag as you go

[LewisB]

The good thing about shearing one of those cam cover bolts is, due to the shoulder on the bolt it stops the thread tightening up like a normal stud does, meaning it stays lose in the threads of the cylinder head. They are easy to shear though. I have managed to undo a sheared one by unscrewing it enough with a small electrical flat blade screwdriver so you can grab it with a long nosed pliers to undo and remove. At least you got it out

As Tony says, what happened to the swarf?

Chris.

I count myself lucky them as it could have been a lot worse. At first I thought I wouldn’t be able to get my drill in behind the wheel and though I might have to drop the engine. Hence why my original post was a tad dramatic haha

[LewisB]

Good save!

Has it recently been worked on? Seems odd to have randomly sheared off.

Yep, totally my fault I think! I recently had the cam covers off to check clearances. I did them up l too tight (I’ve now ordered a torque wrench) but I know for sure it didn’t snap when I did it up! The only thing I can put it down to is that I put a hairline fracture in it, and when I had it running the other day the heat expansion got to it? I know that sounds very unlikely, maybe even impossible? But it’s the only think I can think of right now as I am 100% sure I did not feel it go loose!

[sirch345]

Good save!

Has it recently been worked on? Seems odd to have randomly sheared off.

Yep, totally my fault I think! I recently had the cam covers off to check clearances. I did them up l too tight (I’ve now ordered a torque wrench) but I know for sure it didn’t snap when I did it up! The only thing I can put it down to is that I put a hairline fracture in it, and when I had it running the other day the heat expansion got to it? I know that sounds very unlikely, maybe even impossible? But it’s the only think I can think of right now as I am 100% sure I did not feel it go loose!

Due to that shoulder on the bolt, it stops the threaded part from bottoming out when tighten it up, therefore what happens with over tightening is the threads get stretched before shearing off, don't ask how I know

Chris.

[LewisB]

Good save!

Has it recently been worked on? Seems odd to have randomly sheared off.

Yep, totally my fault I think! I recently had the cam covers off to check clearances. I did them up l too tight (I’ve now ordered a torque wrench) but I know for sure it didn’t snap when I did it up! The only thing I can put it down to is that I put a hairline fracture in it, and when I had it running the other day the heat expansion got to it? I know that sounds very unlikely, maybe even impossible? But it’s the only think I can think of right now as I am 100% sure I did not feel it go loose!

Due to that shoulder on the bolt, it stops the threaded part from bottoming out when tighten it up, therefore what happens with over tightening is the threads get stretched before shearing off, don't ask how I know

Chris.

Thank you engineers who put a shoulder on those bolts

[sirch345]

Yep, totally my fault I think! I recently had the cam covers off to check clearances. I did them up l too tight (I’ve now ordered a torque wrench) but I know for sure it didn’t snap when I did it up! The only thing I can put it down to is that I put a hairline fracture in it, and when I had it running the other day the heat expansion got to it? I know that sounds very unlikely, maybe even impossible? But it’s the only think I can think of right now as I am 100% sure I did not feel it go loose!

Due to that shoulder on the bolt, it stops the threaded part from bottoming out when tighten it up, therefore what happens with over tightening is the threads get stretched before shearing off, don't ask how I know

Chris.

Thank you engineers who put a shoulder on those bolts

I imagine the shoulder is to prevent anyone putting to much pressure on the cam cover seal by over tightening the bolts, also by having shoulders on all four bolts that gives even pressure on the c/cover seal all the the way round.

I'll see if I can find the one I stretched, if I can I'll post up a photo.

I think your theory on what happened to yours is feasible,

Chris.

[tony.mon]

The shouldered bolt is so that the rubber cam cover seal is compressed just the right amount to seal the cam cover in place.
As the seal goes through heat cycles, it effectively shrinks a little. Honda don't want you to simply tighten the bolts a bit more, they want to sell you a new gasket each time, so designed the bolts with a shoulder.

Having said that, I simply use a thin smear of silicon on the seal each time, but try not to get any squishing into the engine, as it will clog the oil pickup filter and wreck big ends, mains and cam journals.

[sirch345]

I found that stretched cam cover bolt today I mentioned above. You can clearly see the threads that are stretched right next to the collar

Chris.