My sump plate isn't sealing against the sump very well. The aluminium is very pitted. What the best route to take. I'm thinking thicker gaskets or maybe silicone.
If and only if the engine block can be got oil free for a while it can be possible to make a smooth surface with something like good old JB weld. BUT you have to clean it thoroughly. Silicone sealant wont stick properly to oily metal either. Go for the silicone sheet idea. Then if it still leaks the engine comes out, you turn the engine block over and clean it thoroughly ending up with carburettor cleaner to degrease then surface it with JB weld, sanding it flat carefully so the silicone seal has a chance. Then if it still leaks , build a new engine with a newer block or exchange it for a recon engine with a different set of problems.
Its a vege engine which was not long fitted before I purchased it last year. I've just made a gasket out of uncured rubber which we use at work which withstands very high temperatures. Will report back how I get on.