Oddjob

Cross posting from the 951 forum, in case any of you 911 Turbo guys can give a water pumper a helping hand...

Never seen this before. I have a pretty good guess, but want to know if anyone has seen this exactly.

Couple odd things:

Almost waxy (not oily) coating, gray color.

Accumulated over about 300+ track miles.

Only on the hose and pipe between the turbo and intercooler. Piping, hose and intake manifold after the intercooler look very normal (slight oil spray).

No change or loss of boost/power. No smoking, no noise from turbo.

Thanks for any insight.

fullquack

I've only seen that gray residue, when I've encountered water/oil/heat combination from a blown head gasket on a water cooled engine.
Although, I have no idea how water could have gotten into your intake system??? A K26 turbo on the 951 does not have a water cooling passage does it?
Mark

Oddjob

Mark,

Yes, the bearing/center housing on the KKK 951 K26 series turbos are water cooled.

I was thinking the compressor wheel is hitting the housing. But with no evidence from the inducer/inlet view, and w/ no noticeable affect on performance (boost), or sound - I am not certain this is the case. Very reputable turbo builder said I would hear a high pitched whine if the wheel was touching the housing.

There is no noticeable play in the shaft.

Next step obviously is to pull the turbo and take the cover off to see.

But thought I would throw it up on the turbo boards to find out if anyone has seen this before. I have not, and I have been tracking/racing turbos for 20+ years - this is something new for me.

fullquack

Jim,

If it were metal on metal contact alone, the residue should be shiny dry powdery aluminum flakes, not a waxy coating. Plus the edges of your impeller should show slight burrs, as a sign of radial contact, I do not see that in your pictures. Furthermore, there seems to be proper clearance between the impeller & the housing outlet in the photos.
You say there is no noticable play in the shaft, are you talking side-to-side play or end play? Side-to-side play can caused the impeller to hit the housing radially, while end play causes impeller thrust surface contact.
The photo looking down the tube, where you have run your finger down, it looks like tiny moisture trails, can be seen leaving tracks in the gray coating...hummmm.

I suppose you could be having a dual issue, a little rubbing & a little oozing of oil or water? Which would make some sense, as the impeller cannot contact the housing anywhere, unless there is wear in the bearing surfaces, thus the seals could be being compromised. Odd things happen at 30-40K rpm's.

Or, were you ever racing in the rain? Water saturating your air filter?

Mark

MUSSBERGER

Condensation and oil? It looks like the film I used to see on blast hole drill rigs which was a mixture of rock drill oil and dust suppression fluid (water and liquid detergent)

Mike Chow

​​​​​​​Hi Oddjob,
I have the same grey residue appears at my turbo and charger pipe, did you figure out what they are? Did U have any problem with your turbo and intercooler?

Mike Chow

I also have that grey residue found at the turbo and charge pipe connection. Oddjob, did U end up finding out what might have happened?

Mike Chow

Hello?
Oddjob you there?
Hope you can shed some light on my situation.

ahenthus

He's still posting in the 951 section. He only posted here to get turbo perspective from the air cooled guys.