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ME 109 wrote:I think the head is more often the problem than the cover.

Theoretically, could the observed air leak result from a cylinder head stud having stripped its threads in the crankcase?

tsa wrote:

ME 109 wrote:I think the head is more often the problem than the cover.

Theoretically, could the observed air leak result from a cylinder head stud having stripped its threads in the crankcase?

I don't think so.
The valve cover gets crank case pressure through the push rod tubes.

ME 109 wrote:

tsa wrote:Theoretically, could the observed air leak result from a cylinder head stud having stripped its threads in the crankcase?

I don't think so. The valve cover gets crank case pressure through the push rod tubes.

Re-reading how I worded my question, I'm not sure if I got it right. I was more thinking of if a stud pulled its threads, could that cause distortion of the cylinder head, that eventually will show up as an air leak?

My understanding is that pulled stud threads more often will result in oil leaks from the cylinder base, or loss of compression, than air from the top of the head, though.

There I said it: air-head

tsa wrote:

ME 109 wrote:

tsa wrote:Theoretically, could the observed air leak result from a cylinder head stud having stripped its threads in the crankcase?

I don't think so. The valve cover gets crank case pressure through the push rod tubes.

Re-reading how I worded my question, I'm not sure if I got it right. I was more thinking of if a stud pulled its threads, could that cause distortion of the cylinder head, that eventually will show up as an air leak?

My understanding is that pulled stud threads more often will result in oil leaks from the cylinder base, or loss of compression, than air from the top of the head, though.

There I said it: air-head

I knew what you meant tsa, but I can't see it having any significant affect on the gasket.

In my opinion, the heads are too strong to warp from a loose stud. The ones that I have seen with a warped surface were due to trauma, as in crash.

Duane Ausherman wrote:In my opinion, the heads are too strong to warp from a loose stud. The ones that I have seen with a warped surface were due to trauma, as in crash.

Heat also plays a big part in warping the valve cover surface of the head, particularly below the exhaust valve. Ime.

SteveD wrote: ↑Wed Jun 15, 2022 11:24 pm Are silicone gaskets still an available and useful option? They got some net time a while back but I don't read so much about them any more.

I've only tried soft silicone ones once on my bike and they were total crap. Never again.
They bulged out and got flattened on all the contact surfaces making them almost impossible to re-position properly for a second go around.

I change my oil every 5,000km, oil & filter every 10,000km.
This might seem a bit excessive, but I like my oil clean.
Doing it at 'round numbered' intervals eliminates the need to keep a record or log book or to remember when it was last done.
Each time I change the oil, I remove the valve covers to drain out the oil that's in them.
This also allows me to do a quick rocker 'wiggle' test, and slight tappet adjustment if I 'feel ' like it needs it.
I re-use the same gaskets over and over and over.
From my experience NOTHING beats the OE valve cover gaskets for durability in this situation.
I just give them a (very) slight coating of grease; I've never had one leak. No goop or sealer ever.
This makes for clean and easy replacement when necessary (maybe every 80,000 -100,000km or so).

All the aftermarket ones I've tried that initially seemed to be as good quality as the OE ones tended to distort and lose their shape and/or crack after only one or two re-uses and needed to be replaced quite often.

My bike only has 540,000km now. Time will tell if I'm doing things right as it gets older.

Nobody ever notices my large r90s style exhaust nuts and black cylinders