increased oil consumption post valve cleaning

My 03 Jetta (120K) has been burning (NOT leaking) oil at a rate of about 1 quart every 2000 miles for at least 30K. This car has been running WVO for 40K, diesel only for last 1000-1500. After scraping the serious carbon build up off the intake valves and ports, the power is way up, smoke is way down, and oil consumption has about doubled. My compression has always been good (~480 x 4), turbo does not seems to be overly loose (tiny bit of side-to-side play, zero in-out) but I don't know what the tolerances are.

There has always been liquid oil in the CCV/air intake tube. The intercooler never drips when I pop the hose, though there is always a 1/8" to 3/16" film on the bottom inside it.

Can the increased air flow be sucking more oil thru the CCV? (was max of 550 mg/str before cleaning, now >900 mg/str)

Could worn/shrunk valve stem seals cause more oil loss than normal during idle? I spend at least 30 min/day in bumper-to-bumper between long hwy runs. WVO in the CC blew out my rear main seal about 30K ago and I suspect it had the same effect on the valve stem seals.

Any other ideas of where the oil is being lost?

Help please

oil rings in the engine is my guess.

I think I'll wait for Franko6 to comment. He has disassembled a number of WVO engines and can comment better.

Why would oil rings be affected by cleaning the intake ports and valves?

Just tried to do compression test. 1 & 2 were both 490, tester sprung a leak while doing #3. The car has plenty of power and speed, turbo runs great (not noisey), no smoke at start up or idle, black smoke on hard acceleration, maybe a slight haze during normal acceleration, no hard starting, block 13 is good (all +/-0.3).

How do I trouble shoot turbo oil loss or CCV oil loss? Can the CCV fail?

I would guess valve stem seals. DId you reuse the seals after cleaning your valves?

bsalbrig said:

I would guess valve stem seals. DId you reuse the seals after cleaning your valves?

Click to expand...

ditto - you worked the valves and the seals suffered - maybe a ester base oil would give them some new life or replace te seals.

I'm thinking that it's the same thing that I've told you all along...

I told you that when you find that kind of build up on the valves in a WVO engine, the rings are catching a lot of stuff. The damage is usually in line with the wrist pin and you get galling from the volume of debris that falls into the cylinder at a steady pace.

The reason that oil consumption has accellerated is that the volume of air that now can pass the intake valves has dramatically iimproved... larger combusion is available and the forces the larger combustions create are showing the true nature of the damage in the cylinders/ pistons/ rings. The rings are damaged and each stroke allows a bit more oil into the cylinder head to be burnt.

The next step is pulling the head to examine the damage. You will undoubtably see the striations in the cylinder walls. Upon removal of the pistons, you might find badly varnished pistons and the top ring might be stuck in it's land.

For those that think it's vavle guides, I say this over and over...

Valve guides in a turbo diesel reduce the oil usage neglegibly. Since a turbo engine is pressurized on the intake as well as exhaust, you do not get oil sucked into the intake valves like you would with a N/A engine. The seals help with blow-by to a very minor extent.

Not trying to be a PITA, just trying to understand.....

Assuming that the cylinders/rings are damaged, shouldn't that show up as lowered compression?

Is the intake pressurized during idle and/or decelleration when the turbo is not running? I spend a lot of time sitting in traffic after running on the highway.

What's it going to cost me to have the head pulled/replaced/rebuilt?

Thanks again Frank, hope you are staying high and dry.