Last autumn I started the engine after the van had been off the road for 2 years due to Covid. A lot of oil began coming out of the rocker cover on cylinders 3 and 4 (passenger side of van.) The engine had done 150,000 miles,so I installed new barrels and pistons,and lapped in the valves. But the problem has not gone away. It's as if there is a lot of pressure in the rocker cover,forcing the oil out. I don't understand why,because surely the crankcase ventilation would deal with any build-up of pressure. Has anybody got any ideas? I'd be most grateful!
Welcome to TLB Phil. If you are concerned there may be crankcase pressure remove the oil filler cap and see what comes out.
Indeed and I doubt if it is crankcase pressure but it’s easy to eliminate by just removing the cap. After being laid up for a couple of years the cover gasket could have dried out and I’d be looking at the gasket condition and quality, bail pressure or simply a misplaced gasket. I wouldn’t have changed B&Ps to try to cure a rocker cover leak unless there were other symptoms that we don’t know about.
Normally a breather box set up drains back into the rocker cover, so I’m thinking it is not under pressure? Try swapping rocker covers and see if the leak moves? My thinking it is a physical thing. It is either the rocker cover, bail clip or gasket?
The 3/4 side could be a spray of pressurised oil from the oil cooler or oil filter assembly on that side.. .. not necessarily the cylinder head itself.. In normal running there is a pool of oil in the head but it should be under very little pressure or in fact slight negative pressure if the crank case PCV is working properly. Oil will still run out of the gap between the gasket and the head if there is a gap, and air will get in and mess up the mixture by rushing through the ventilation system into the intake.. Is the rocker cover flat .. nobody trod on it ? .. and the bail spring still springy, and the gasket actually in straight so it contacts both sides all the way around ?
Thanks for all your ideas. I renewed barrels and pistons while I was sorting out rough running,which turned out to be a burnt exhaust valve on no.4 cylinder. All seals and gaskets were new,and positioned correctly,so I remain puzzled.
I guess over my years of VW ownership the thing I've failed to get right on so many occasions is refit the rocker covers so they don't leak, though I think I've got it these days. Applying the bail springs can push the cover sideways so the gasket is distorted. You may think you've got it on right but there it is dripping onto the heat exchangers again. The covers fit two ways round and also the springs lever off to the top or the bottom and this has some bearing on how well they seal. People disagree which is correct, but I put the covers on so the VW symbol inside the cover is upside down, and I lever back on from the bottom.
Did you use any sealant on the rocker cover gaskets. Also are they the proper cork jobbies. Very odd that it should be only on one side.
Either the leak is not from the rocker cover at all or the gasket is too thin (poor quality from JK for instance), or the gasket has moved as you’ve fitted the bail, or the cover is distorted, or the bail is weak. Check that the cover face isn’t being held away from the head (especially if you are using thin gaskets) a film of sealant on the cover can help retain the gasket in the correct position - but don’t use sealant on the head.
One thing I ended up doing on my T1 engine was to take it out, take the fan housing and tinware off and put it back in and start it up. The jet of oil from the cracked oil way (specific T1 under-oil-cooler-boss fault) became obvious. As it was for only about a minute running, you dont need air flow at idle. [If you read the books on the highest output aircooled drag racing engines, they disconnect the fan for more power, or even rely on storing the waste heat in massive billet cylinders and heads without fins.. ]
This is what was happening to one of mine, the casting boss on the front of the head was stopping the cover sitting properly, some of the gaskets for sale, not just JK's, seem to be thinner than previously, credit to @Zed for spotting that one
Anyone advise which gaskets are the issue. JK swell victor reinz I think. Got a box full of em! Not noticed any difference for years since the wider ones became no longer available. Problem with the ones you currently get is they aren’t wide enough on the faces unless your bang on they leak. Plus they do wriggle around a bit before they’ve been compressed a bit. Tbh the older ones which I haven’t seen for some time were vastly superior. You couldn’t get it wrong really
Pretty certain the ones I had the problem with were M7, they're fine after I filed the casting's boss/sprue down a tad.
Victor Reinz and Elring worked for me, the cheap ones from JK didn’t. Other suppliers also have poor quality.
I’m confused which cheap JK ones are these? Buy my rocker cover gaskets from JK and they are elring! Can’t recall them ever selling anything else!
