Where is my oil going?

[JDuval]

Hey guys,
I know I've asked this question a thousand times now, but we have yet to really debunk it.
I have been consuming alarming amounts of oil in my AAZ since the day I got it. It was leaking past the rocker cover and past the ccv grommet. I fixed these leaks. It also seemed to be leaking down the line going from the air filter to the turbo as there was a large oil spot on the engine mount directly beneath. After replacing the ccv and cleaning the engine I cannot see any external leaks at all.
Over a ~750 mile drive yesterday I went through 4 quarts of oil. I'm losing A LOT.
Where is it going? If its not leaking, I must be burning it right? I'm not getting any noticeable blue smoke though.
This engine had the head gasket and head replaced a while back by the PO. I have heard that a rebuilt/new head on an old block can cause the piston rings to die prematurely. Is this a likely source of my problem? I would just expect to see blue smoke if I was going through oil like that.

Could it be the turbo seals? Oil getting forced straight into the exhaust and clogging in the cat or muffler?
Any insight of any kind would be awesome.
I'm planning on getting a leak down test soon. Would that narrow this down significantly?
Will any old garage be okay do a leak down test on these diesels?

[libbydiesel]

Step one would be to run the crank vent in a catch can.  Be careful when driving an engine that is consuming that much oil.  It can run away.

It's very UNlikely that the turbo seals are the issue.  Even if the shaft seals were not present at all, they wouldn't cause that much oil consumption unless there was another issue like a plugged oil return line or plugged crank vent system. 

A new head won't do anything negative to the piston rings.

While a leakdown might show bad rings and bad rings can cause high oil consumption, I have an AAZ engine that got excellent leakdown results and yet burned a massive amount of oil.

[JDuval]

Okay, thanks for the info.
Is the catch can just to see how much is going through there?
I just run the line from the ccv to a bottle instead of to the intake tubing right?
I think I need to make holes in it too, right?

[8v-of-fury]

If you can run the catch can so it drains back in to the front of the block, there will be no more oil burnt through the CCV to intake pipe.

I too must look in to making one of these up. lol

[JDuval]

How would you go about that? You wouldn't just drain into the line from the block to the ccv would you?

Catch can aside though, I can't really be losing that much through the ccv system, can I?

[8v-of-fury]

If the block is pressurized with crank gases, it is the easiest and least restrictive path for the oil to flow. Directly in to the intake system lol.

[JDuval]

I guess so yeah. But why would the crankcase be getting that pressurized?

[hillfolk'r]

Its either going past the rings or valve guides,under boost id suspect.
yea rig up a catch can,clean out the intake boot,and the hose off the compressor to the intake also....drive it around some,see if ya get oil back in the compressor side..thatll determine if its the turbo or not...
yea a leakdown isnt really gonna show bad oil rings,and the excess oil will or can mask a" bad" cyl if theres enough...
you could just run the pcv hose into an open antifreeze container with the hose going to the bottom,and some holes towards the top...see how long it takes to fill up..dont forget to plug the intake nipple u took the pcv hose off of.
hey heres a little radical idea..do the hose in the antifreeze bottle deal,and remove your hood.drive around and see if your bottle is smokin and chuffin alot,especially under boost

[burn_your_money]

A clogged air filter can also cause high oil consumption, probably not this high but it could contribute. Remove the air filter, and then look at the pre-screen in the airbox. That thing usually gets full of junk and no one thinks to clean it. I'm assuming MK3 or B3. Mk1s and Mk2s don't have this.

If the oil was being dumped straight into the exhaust side of the turbo you would have very white smoke blowing out the tailpipe. Also, because it's a diesel you are not very likely to see blue smoke when oil is being burnt, simply because the engine can actually burn the oil fairly cleanly. It's just more fuel in the engine and likely all you'll see is increased black smoke.

You can remove the oil filler cap with the engine running and rev the engine up. If it's blowing smoke you've got issues inside the engine, or a very bad vacuum leak. For those people reading this that don't have an AAZ, make sure your car has a cam baffle before doing this or you'll spray oil everywhere.

[JDuval]

Thanks for all the info guys, I will check all that out this afternoon.
I have noticed that when I remove the oil filler cap after I've been driving and need to top up the oil, a looot of smoke comes out.
So there is something wrong internally, then? I have looked for vacuum leaks before but I guess I could have missed something.

[burn_your_money]

It could also be a clogged air intake, I forgot to mention that in my last post. It pretty much rules out your turbo though (hurray?)

[JDuval]

Haha, I'm not sure that's something I want to be excited about. But, I'm happy to be narrowing down the issue.
So cleaning the air intake tract would probably be a good place to start then, right?

EDIT: about 290k on the engine, and I'm not sure if the intake was ever cleaned. It's probably worth doing, right? I can't see if it's really dirty because of the 90degree bend on the manifold, but I would assume it is.
Is it a pain to remove and reinstall?

[burn_your_money]

If you don't have an EGR, you don't need to worry about the intake. If it's dirty enough to need to be cleaned, your engine is probably toast from all the junk that got past the air filter.

The part you need to clean out is in the airbox.

[JDuval]

Makes sense. I'll take care of the airbox either tonight or tomorrow and report back.

[JDuval]

I cleaned the airbox--it wasn't plugged up to begin with though. So what are we looking at now then? Internal issues?

I also noticed what appears to be a little oil floating in my coolant...I'll get a picture soon. I know this car had head gasket issues before...and the mechanic that replaced it screwed it up the first time, resulting in him needing to put on a different head. Maybe he botched it again?