oil leak

hi everyone, my 300tdi disco is leaking alot of oil out of the rocker cover (under the gasket at the front to be precise) just wondered if you guys have any ideas? i took the oil filler cap off and there was some whispy white smoke coming out (not alot though) any help would be really great cheers

The fumes and whispy smoke is fine.

Just fit a new rocker cover gasket. Do it carefully, clean the head where the gasket sits, and clean the flange of the rocker cover.

If it was MY car, what I would do would be to glue the new gasket to the rocker cover using Hylomar or similar, and wait for it to set before fitting it to the engine. This way means the gasket comes up in one piece with the rocker cover next time.

CharlesY

thanks (once again! fuel problem seems to be gone now!) CharlesY! your always a great help! just to put my mind at rest though, should there be much pressure under the rocker cover its not blowing the oil cap off when driving or anything but there is alot of oil coming out should there be a breather or anything? thanks again

I have the same problem with the rocker cover leak and I think its a common one. I will do as CharlesY has suggested and get a gasket and some Hylomar. As far as pressure goes I dont think it should be too much. There is a crankcase breather that takes fumes away into the inlet tract i think. If theres a blockage in the crankcase ventilation valve or pipes somewhere then the pressure could increase I guess. However, I'm no expert.

If there was no "breather" system, as used to be the case on old cars, there would always be a slight trail of wispy steamy vapour leaving the engine from the vent pipe that allowed the fumes to escape to the atmosphere. Really bad cases left trails of fumes like a smoke screen.

Fumes? What fumes? How come fumes?

Well, it is a mixture of stuff, almost all of which has come past the piston (despite the rings) from the combustion chamber space ABOVE the pistons, and thus into the crankcase space BELOW the pistons. If there was no vent, the crankcase would pressurise, probably blow out oil seals, and generally make a big mess.

These fumes are a mixture of AIR, unburnt fuel, and exhaust gases. Nasty.

Modern cars have simple methods of sending these fumes back to the inlet manifold and into the engine to get burned up, thus cutting down pollution, and making your engine a bit less oily.

If the anti pollution fume breather valve(s) are working, there should be a very slight depression (low pressure compared to outside) inside the engine, thus cutting down on the chances of oil leaks. Better, all the water vapour that passes the piston (steam ...) is taken away, and without that water the nasty acids that eat your engine cannot form, at all, or so quickly.

Moral - make sure your engine breather system works. Clean the filler cap in kero (petrol if you take care to dry it well) and make sure all the pipes and hoses are clean inside. They can gunge up till there are BLOCKED in no time at all, and this can cause monster oil leaks.

CharlesY

So if you are getting a lot of pressure at the oil filler cap that could mean loss of compression due to bore /rings worn and thus a pressurisation of the crankcase. I had an astra that had a nasty habit of chucking all the oil into the air filter via the PCV and then out all over the exhaust manifold. I finally took the head off and found the reason - a holed piston. The amazing thing was that the car was still running quite well apart from long periods at high revs when the oil would finally all come out and you had to stop!

just had chance to have a closer look its not coming out of the rocker cover gasket at all, its coming out under the thermostat housing at the head gasket just bubbling out, there is no loss in compression or anything it just seems that the oil is seeping out. was bubbling but tweaked the head bolt a little and it stopped bubbling but after a short drive there still seemed to be some coming out.
just towed the vets td5 defender up the yard hill so am glad to see its not just my landy that has gremlins!!