i have been in the process of tracing an oil leak to it source for some time, i originally notice this last summer during the hot weather after the engine temp got upto about 100c on the odd slow bit of riding, i moped it up and it seemed to disapear, till this year i noticed again after some slower riding when the engine temp had been up a little puddle of oil once again behind the rear cylinder, at first i though it was coming from the rocker cover, but since renewing the gasket and being precisely careful (as if performing surgery to her) replacing the cover and sealing it, i found it odd that i still had a leak on my return from france the other week. From further examination it appears that the leak is coming from under the belt cover near the rear cylinder head nut area.
whats the next thing to do?
whats under the gasket to the side of the cylinder, could it be coming from under there? do i attempt this leak myself? looks like a belts off job??
The piccie is a bit blurred but from what you've said, I'd guess it could be the oil seal on the camshaft itself. Belts off, pulley off, pull the seal and replace.
possibly could be the camshaft, but im more enclined to think that its a leak somewhere in the cave type recess of the head retaining nut, there seems to be some gasket mounted horizontally adjacent to this point?? cant see any traces of oil falling down from above this point after a clean off and re examine?
Just been looking at the parts diagrams and if you're 100% sure the gasket isn't leaking, it looks possible it could come from the join of the cam journals?? The bolts that hold these down have a secondary thread on them for the covers to screw down onto. If one of them undid itself when the cover has been removed, it could be enough for a leak???? Especially when it warms up. Long shot??..........they should be tighter than the cover screws but so are the pulley bolts on the 748/996 but they sometimes unscrew when the tensioner nut is undone.
I've had a chat about this and apparently it's not uncommon for the oil to get up the stud hole. There's an O-ring at the bottom of each stud that doesn't work too well?? The trick is to cover the threads and washer in Threebond or such like and re-torque the nut down. This saves pulling the barrel off to sort the O-Ring. Might not be the problem in your case but another thing to check out.