Having filled my B40F primary chaincase to the correct level (it has a B25 cover) oil then escaped readily from the alternator apperture. Parts manual shows it should have a gasket....which it didn't ....so have just cut one from gasket paper.
The ID of my gasket is a bit smaller than the cover mating face.... so a lip open to the oil splash.
Which raises a novice question.....does it matter here?....or generally when making gaskets?..... and would it be better to cut the ID down to match as close as possible to the mating face?
I just do a dirty finger rubbing on alloy most of the time , if it's a solid cast iron lump, I might tap around with the tiniest hammer on the edges , you can also trace around the outer edge and find something to fit nice in the bolt holes , give it a sharpen and mark all the holes , then I just free hand a 5 or 6 mm line around the inner , stamp the holes on the end grain of wooden block first otherwise you'll split your thin gasket then cut it out with scissors. Cheers .
I have a similar problem with my B44, but the oil is escaping from one of the screws holding the alternator cover in place. I only realised this after fitting a gasket (there wasn't one fitted).
I might be tempted to trim the bottom edge of the gasket, it might form a mini reservoir holding a small amount of oil behind it just waiting to find a way to freedom.
I bought a cheap set of hole punches to stamp out the holes in gaskets. I find putting one of those green cutting mats from a craft shop underneath makes for a clean cutout.
I have got an ancient bottle of engineers blue a thin coat wiped onto the engine face then press the gasket paper onto the blue and you get a nice print you can cut round. To cut out the holes a set of punches is great but any old bolt can be ground to make a punch.
Well I trimmed the gasket to match the mating face (but not at the 4 screw hole locations)
Didn't try it before the trim, but alas still leaking at alternator apperture. Not from the screw holes, but lowest part of apperture.
Hi,
Have you checked that the cover/plate is actually flat? It may be slightly distorted after years of being tightened. Also, have the screw holes become slightly raised? Or both of the above.
Dave.
Ah. Yes cover plate is not quite flat. can feel it rock a little in situ and on kitchen work top. screw holes seem ok/not raised
It fits better if I rotate it 90 degrees. The gasket I made is quite thin, not sure how thick/soft they are supposed to be but maybe I make a thicker one from something, or buy one.
I could wet sand on glass........but no guarantee that the tabs in the case are not out.
You could try making a gasket from Neoprene rubber sheet I have had success with it in the past with carburettor flange gaskets that weren't the flattest. You can buy a A4 sheet in thickness starting at 1mm on eBay for not much. Cuts okay and punches holes easily but make sure it's oil resistant natural rubber will turn hard and crack.