... But that wouldn’t define the oil found in the inter cooler. Not excessive although wet. 280k miles later ... I hear they all get a little wet as some oil slips through the turbo. The core question is can excessive oil level allow more than the traditional small amount to seek through the turbo?
I’m trying to determine if the turbo is completely in need of replacement.
Again - many thanks for feedback.
A small amount of oil will seep past the impeller seal. This is normal. Since the turbocharger spins very fast, and the temperatures are very high, a normal neoprene type seal that would eliminate all oil leakage is not possible. Instead, they use what is called a labyrinth seal. It allows a seal to happen, while not perfect, it works well and allows nearly frictionless seal operation past 100k (yes, more than 100,000) rpms, which is where the turbocharger will operate sometimes.
When the turbocharger isn't working hard, the charge air pressure in the impeller is low, and that is when some oil will seep past the seal. It isn't a large amount.
As has been mentioned above, the CCV vapors are far more likely to be the source of the condensate you are finding downstream of the turbocharger. The vapors come in, condense in the intercooler, and can pool there a bit when the engine shuts down. What you get as condensate are oil vapors, combustion byproducts, and water. There wouldn't be enough to cause a runaway.
If run well, the accumulation will not be excessive. If the engine is always run gently and never ever gets floored, then you can have more buildup. I ran into one where the owner complained about it 'surging' on startup. I found that on startup, the rpms would surge up and down about 100-200 rpms worth. I did a timing belt job on that car (which is why I was there) and drained quite a bit out of the intercooler when I disconnected the lower hose. After the job was finished, we fired it up and I then ran it up and down the street outside the subdivision and fogged it for mosquitoes at the same time. I doubt my efforts were appreciated however, as it was Phoenix in December where mosquitoes aren't really a problem. But the surging went away after the blowout.
Just remember that paying attention to the engine oil level will tell you whether there is excessive oil leakage past the turbocharger seals. A failed turbocharger will cause heavy smoking and the oil level will indicate a consumption of oil faster than the fuel. There will be no question. If it happens, you shut down immediately and don't bother looking for a convenient place to pull off the road or try to make it home. That would be a disaster. If you have to, leaving it in gear and hitting the brakes to stop would work.
If you are getting boost when needed, the oil level is stable, and the exhaust is not driving a petition to kick you out of the neighborhood, you're fine.
Cheers,
PH
This was the clean version!
