Less obvious source of oil leaks on B4?

[sfierz]

Hey guys, I just got done with changing out the oil cooler O-ring, oil stand gasket, CCV tube and a leaky oil pressure sensor, but it seems I may still have a pesky oil leak somewhere. I'm not sure if the is just residual oil caught up in the foam of the pan leaking out or if there is indeed an active leak. I have had the intermediate shaft and crank shaft seals changed, the valve cover gasket and cam seal replaced, and of course timing belt, water pump, and harmonic balancer replaced. I have checked connections at the turbo oil line and they don't seem to be leaking, so where could engine oil leak other than these? The clutch has been replaced and the rear main oil seal replaced as well. I suppose it is possible that some of these were not replaced correctly, but I know I bought quality German parts and had a trusted shop well-versed in VW and TDI's put these parts in. I'm just kind of at a loss as to where oil could still leak.

The oil cooler repair seems to have helped, but I guess I was expecting near zero oil leaks but maybe that is too much to ask on a 96 Passat TDI with 236k miles. I'm thinking when I get time I will go in and check some easy places like the valve cover gasket since this would be easy to R and R in case a seal might have gotten pinched on install. I don't know about the oil pan gasket, I suppose that could be a point of failure if it hasn't been replaced or if the clutch install disturbed it in some way.

Other than that, I am just grasping at straws here and need some help. I suppose time may tell since things may be "settling in" or residual oil may still be leaking off the engine pan. It was pretty soaked when I removed it for the oil cooler fix.

 

[Chessie]

Leak check..

You have covered most of them! The trouble is, oil could leak from LOTS of places, and you'll need to narrow down the source rather than just say "where can it happen?".

The main seals (for example, the rear seal, at the tranny) can indeed leak after installing a new seal.

If I were you, I would remove the lower engine cover and look around. This will probably prove fruitless. The trouble is that oil flows nicely when its warm and at 60 MPH. So you need to clean things up and look again.

Look after it has just been cleaned and you have run it for about 5 minutes, up on jack-stands or car ramps. If you can't locate it yet, let it run a little longer, and try again.

If still no, then drive it for 5 minutes and drive up the ramps and look again.

As a final helpful diagnostic tool, some people will put baby powder on the area where oil is suspected to be leaking from and see if it gets wet with oil.

You're going to have to be a detective and "think like an escaping oil molecule".

Either that, or just put a pan under the car in the garage and just ignore it!!!

Chessie

 

[TonyJetta]

I would also inspect the turbo oil feed line, and the return line to the crankcase.

How much oil and how frequently are you adding oil?

Have you checked the lower intercooler hose for oil?

How many miles on your turbo?

Tony

 

[Warthog]

Chesie's right. Remove the bottom cover and clean things up really good. then go for a drive. Immediately have a look.
Usually fixing the oil cooler and surrounding connections stops the nastiest leaks.
It did for me, and my Passat has about 180K...

 

[Abacus]

I didn't see the EGR weep hole mentioned, that is an issue on mine I will rectify today. It's dripping down under boost and running off the back side of the motor. I am going to tap the hole and thread in a hose barb and direct it back into the engine where it belongs.

Also look at the valve cover and basepan gaskets, if they are overtightened, they will leak oil.

I have eliminated all but the EGR weep hole on mine, and it has 341K on it, so it is possible.

 

[sfierz]

It's definitely leaking on the ground not into the intake tract. The turbo is original and has 236k miles on it. I find very little oil in the intake when I check it. I have been trying to track these leaks down precisely because I find it leaked on the ground. That jet black diesel oil makes a pretty nice spot especially on concrete.

I'll take a look at the pan and valve cover gaskets next. The turbo oil feed seems fine.

Update: there seems to be quite a bit less oil leaking now after the oil cooler/CCV tube fix. I am still disappointed that there are any leaks at all, but at this point they are extremely minor. I'll look at the valve cover gasket since that was recently replaced and the oil pan, which is suspect. I don't believe the turbo oil feed is leaking since that would put a huge mess on the ground unless the cylinder head banjo joint is leaking as I reused the old crush washer. Overall, much better now with the leaks.

 

[sfierz]

Ok, I think you are on to something here. The T-belt was recently changed and the valve cover gasket replaced. I've found fresh oil around the valve cover area and suspect it has been overtightened. I'm going to remove and retighten as soon as I have a couple hours to spend in the garage.

I didn't see the EGR weep hole mentioned, that is an issue on mine I will rectify today. It's dripping down under boost and running off the back side of the motor. I am going to tap the hole and thread in a hose barb and direct it back into the engine where it belongs.

Also look at the valve cover and basepan gaskets, if they are overtightened, they will leak oil.

I have eliminated all but the EGR weep hole on mine, and it has 341K on it, so it is possible.