Left engine cover leak (the one that contains the starter clutch) gas engine tom

Look here, the grommet sealed originally by being crushed on all 4 sides, if it slips in and out of the notch in cover there then you can crush at the gasket face to seal all day long and still be leaking on the rounded side(s) that match the notch. Why I bring that up is that the pic seems to show frayed rubber at both ends of the notch outer corners, meaning the rubber piece is fragging out to be cracked or frayed inside at the rounding to leak no matter how tight you scrunch down on the gasket. Not yours but if the same way………

If the rest of cover has no dents in it one could simply drop the gasket and using a good grade of gasket maker seal it with that alone, but will not likely stop the leak. You’ve lost as least some of the rubber compressibility, the rubber has a notch formed in it to lose squeeze there. Yours again may be same way. You could carefully cut a piece of gasket material or even thin metal exactly the same shape and size as that notch and say temp glue it to the rubber to make a stuffer to tighter push in on the rubber to seal better, that may work. The shape and size are critical to avoid a worse leak.

More than one way to approach fixing that. The problem is not one of gasket goop, which immediately flexes/flows out of the way of crush when the part is installed, it is one of a substance/material staying exactly in place to force the existing rubber to be crushed more, gasket goop will not do that.

Look here, the grommet sealed originally by being crushed on all 4 sides, if it slips in and out of the notch in cover there then you can crush at the gasket face to seal all day long and still be leaking on the rounded side(s) that match the notch. Why I bring that up is that the pic seems to show frayed rubber at both ends of the notch outer corners, meaning the rubber piece is fragging out to be cracked or frayed inside at the rounding to leak no matter how tight you scrunch down on the gasket. Not yours but if the same way………

If the rest of cover has no dents in it one could simply drop the gasket and using a good grade of gasket maker seal it with that alone, but will not likely stop the leak. You’ve lost as least some of the rubber compressibility, the rubber has a notch formed in it to lose squeeze there. Yours again may be same way. You could carefully cut a piece of gasket material or even thin metal exactly the same shape and size as that notch and say temp glue it to the rubber to make a stuffer to tighter push in on the rubber to seal better, that may work. The shape and size are critical to avoid a worse leak.

More than one way to approach fixing that. The problem is not one of gasket goop, which immediately flexes/flows out of the way of crush when the part is installed, it is one of a substance/material staying exactly in place to force the existing rubber to be crushed more, gasket goop will not do that.Yep, my grommet is pretty much in the state of the one in the picture.

However, the grommet’s flat face (the one that goes against the gasket and the engine case mating surface behind it) doesn’t sit tight against that line. When the cover is off, I can easily push it with my finger below the cover mating surface. I thought it wasn’t that critical because there’s no real oil pressure there (or so I thought).

But with what you said, I think I would partially fill the groove in the round part of the grommet with some RTV that would make the flat face stand out of the cover mating surface a bit and let it cure before installing the cover. Ideally, it will "prop" the grommet and push it harder against the case. The idea is to "add rubber" to the grommet where the rubber has shrunk with time.