somehow seal the dipstick better, an o-ring maybe?
My 91 NA diesel Jetta has only 126k miles on it but has very bad blow-by. The vent from the valve cover vents fine but I'm still getting oil pushed out the top of the dipstick tube. No other oil leaks currently.
Other than new rings, any remedy to prevent or slow the oil loss out the dipstick tube?
I've bypassed the intake for now and have a hose that leads to the ambient air. I no longer have oil coming out the top of the dipstick tube - which is a great relief. There are no other oil leaks. Apparently I will need to do new rings but I don't want to do that until the fall.
vacuum leaks will make more blow by than normal.. 126k miles isnt enough miles for an engine to be running away on its own blow by..
and check that the ports in the intake are not even PARTIALLY BLOCKED.. you should take the intake manifold off, and clean everything out of those ports.. they like to get clogged often.
it goes from the valve cover, then the hose splits to 2 hoses, and the hose feeds 2 ports on the intake.. one side of the hose feeds cylinders 1&2 with blow by gasses, the other side of the hose feeds cyls 3&4.. well, the actual ports in the manifold LOVE to get clogged up with gunk. they dont get 100% clogged, but they clog enough to make problems for you..
and venting your crank case to the atmosphere is probably the best thing to do, for the time being..
OK. I pulled the vacuum line from the vacuum pump, started the engine and loosened the oil filler cap. With my finger plugging the pump I observed slightly less venting from the loosened oil filler cap as compared to venting without my finger plugging the pump. I'm assuming this means that vacuum leaks are not contributing significantly to the blowby I'm experiencing.
With the vacuum line re-attached to the pump, I observed about as much blowby as with my finger plugging the pump.
It is more likely the valve stem seals and/or guides are worn out at that mileage.......which will give you a lot of blow by.
The factory inlet manifold has cast into it, 'restrictors'....to prevent a run away engine if too much blowby is present. You can drill them out to the size of the vent hoses, but you risk a runaway engine.
Venting to the atmosphere will stop the oil leaking out the dipstick and other seals for now.....it will vent better than through the restricted manifolds.
If you go around a long corner, like one of those freeway onramps that are curved 270 degree's....and it smokes like a pig when coming out of it at full throttle....the valve guide seals are worn out. What's happening on corners, is the oil is pooling deeper than usual at one end of the head, the oil is going past the valve stem seal on the exhaust side and clouds of smoke appear out the exhaust.