TurboTommy

But then that nipple would never see vacuum; aren't all the vacuum lines inter-connected?

Oddjob;
when you say you think the oil is getting to the boost control system via the "intake runner/banjo", I'm assuming you mean from the charge pipe going into the IC. Yeah, I would think that's the only way the oil would get there. And, I guess, that amount of oil can only get there from the turbo. Maybe the oil that's lubricating your turbo is not draining properly. Even with a newish turbo, that oil might get through to the compressor.

Van

Tommy, there are banjo bolts between the 3rd and 4th intake runners.

Also, I believe the nipple at the bottom of the throttle body will see vacuum (but not as much as after the throttle body) from both the low pressure caused by air rushing by when the throttle body is partially open and the turbo's not spooled up; and by the blow off valve releasing pressure from the hard pipes/intercooler back to the j-boot when you take your foot off the gas (the air rushing through the BOV will leave low pressure behind).

TurboTommy

Yeah, I know there's a banjo fitting between 3 and 4.
But, he couldn't get oil to his boost control system from there.

Oddjob

Yes, from the banjo connection line in the runner pipe between the turbo outlet and intercooler inlet - my reference was just a reply/answer to the below question:



I could put an in-line air filter (like a moisture separator) in the "banjo line" to see if that collects a lot of oil and eliminates the excess oil throughout the rest of the system. That would reduce the possible sources down to the turbo and breather blow-by (which I think is unlikely because of previous catch can installation and excellent leakdown #'s).

So, if the oil is coming from the turbo, why so much from 3 different turbos, rebuilt and new units? Either very bad luck or the oil supply and/or a drainage problem causing higher than normal oil pressure in the bearing housing? Last time I swapped out the turbo, I poured oil down the drain/return and it seemed to drain fine.

Also, regardless of the source and amount of oil mist blowing through the intake, the oil should mostly end up in the cylinders, since that is where all the intake air flow goes - many of the vacuum and control lines are static pressure lines, so Im not sure why oil mist would be carried to the places Im finding it (waste gate and diaphram valves). If you blow through a straw, spit will fly out the other end, carried with the air flow. If you put your finger the end of the straw, you pressurize the air in the straw, but there is no airflow and no spit is carried down the straw to your finger tip.

The only thing I can think of, is if the diaphram membranes in the valves and WG are leaking, then the airflow would carry oil out to these components. But Ive had the WG housing apart and it looks fine, and seemed to seal fine when I bench tested it with air pressure to chart a valve opening vs pressure curve.

So I dont think this is normal because it doesnt seem like it should be; but I cant find anything wrong so just wanted some feedback to see if others are getting oil in these places - doesnt seem like anyone else is (?).

951and944S

Jim, keep in mind that air charge pulses (containing oil) oscillate due to open and closure of valves.

The stream of flow in an intake system isn't solely one directional as your spit in a straw analogy.

T

Oddjob

Youre right with respect to the intake manifold and associated flow pipes and hoses, but I will still try to argue that the "straw" is reasonably correct for the control lines to the WG and to the charcoal canister diaphram, heater control valves, etc, which are in effect dead ended - should be nearly zero airflow to those items.

The oscillation in these control lines would be from positive to negative pressure depending on boost (pressure) vs. off boost/closed throttle (vacuum). So back to my simplified analogy: blow, then suck, then blow into the straw with your finger continuously plugging the end - its not actually zero flow, because the straw is evacuated under vacuum, then refills with air when pressurized; but the flow rate and velocity would be so low that its not enough to carry a significant amount of entrained liquid particles (especially a very viscous liquid like oil).

But if Im wrong, I would be expecting some others to chime in that have seen/found oil in these same places (?) - which is why I started this thread. So keep the ideas coming.

Thanks,

vette951s

Jim- My previous questions were in query for association with my excessive oil in the intake tract being attributed to a Garrett ball bearing turbo speced by Milledge and built by Innovative Turbo. After no improvement in my situation after a turbo rebuild, a whole new turbo center section was installed with Innovative's "latest and greatest" with some improvement.

For your situation, I would look towards your Evaporative Emissions System. You may have a problem such as a ruptured diaphram in your carbon canister purge valve and a plug in the fresh air vented portion of your carbon canister. When you run your engine, the fuel in the gas tank is heated and expands. When cooled, it obviously contracts and if your evaporative emission system is defective/altered, it can draw from the intake tract towards the purge valve. I don't know if your vacuum routing somehow interconnects your boost valve and the purge valve.

All turbo cars seem to suffer from some amounts of oil in the intake system. Cleaning out the intercooler of oil is a normal maintenance item for a track car.

John