Need help finding oil leak on mk1

Hi, I've had my golf mk1 chico which was originally a 1.3 for almost 5 years now, it's had an engine change to a 1.8 adz about 3 years ago, but it's always had a terrible oil leak with the new engine (2nd hand), i never used to car enough to start worrying about it, but recently the car has become my main work car and now it's a problem, as soon as it goes on the freeway for about 20 k's the oil light will come on and oil smoke emanate from the gear stick and from around the engine, and the clutch starts to slip terribly, only when i avoid long trips the clutch will eventually start to grab again, after a week or so

now here's the story, i've changed the main oil seal on the engine by the gearbox side, i bought the seal which comes in the plate, used red/orange silicone sealant, let it dry for 24 hours+, after all that, the leak still seemed to be there, that as soon as the engine gets hot the oil will drip every second off the bell housing, so i've decided to try and change the sump gasket, also siliconed it up, which i suppose may not have been necasary because it's rubber, but i don't know where to look anymore, i can't figure out where the oil leak is, what are the checks that i should do, or what can i try to pin point this leak, i've tried looking with a flashlight into the bellhousing while the engine runs it seems there's oil dripping off from the big plate which seperates the engine and gearbox then in falls onto fly wheel and then flywheel to the bottom of the bell housing then it drips out

i found three bolts around my tapit cover which were a bit lose, i tightened them up, but i can't suspect the tapit cover gasket cause i can't see oil running down from it, unless it's seeping through where i can't see it, and all the oil that leaks comes off the bottom of the bell housing

Did you replace the crankshaft oil seal?

Macca said

Did you replace the crankshaft oil seal?

i changed the big round seal which goes around the crankshaft at the gearbox side with the whole plate, the old plate had a paper gasket the new one had rubber around it, we siliconed it up too, i replaced the the valve cover gasket yesterday, but i didn't add any silicone sealent to it, not sure if it could leak cause i didn't add the sealent, it seems there's alota oil around the intake manifold and around the back of the engine, the old valve cover gasket did look perished at a few places, but it's still leaking, my next step is to try and silicone up the gasket which i installed, also i seem to have mixed up those long plates which goes on both sides of the valve cover, can either side go on any side, or was i suppose to put them back the same sides? the problems are the leak uses about a litre of oil for every 30km's and the clutch slips after long rides, so the clutch slipping and the oil dripping off from the bell housing kept giving me the idea that the main shaft oil crank seal was leaking, but it doesn't seem to be, its as if there's a leak anywhere on the engine it seeps its way through to the clutch and drips down from there, i also cleaned out the breather pipes they were actually dirty and stuff, cause it has two breathers one in front of the engine and one from the valve cover, not sure how serious the engine side breather being a bit dirty was, like black sludge,

if anyone can give me a few clues id apreciate it, i also removed the plastic covers for the cam shaft belt, the belt and the pully's are dry as a stick, so i wouldn't think it could be over there, i also need to do an engine wash, it's full of oil everywhere, don't know what's spilt oil or anything anymore, cause we top it up so many times

I think the best thing to do would be to clean the oil off all of the engine then check the complete engine from the top down.
Both engines Ive rebuilt Ive never had to use sealant, just replaced all of the gaskets with new.