What symptom = failed turbo?

[hobieboy]

I'm chasing an occasional smoking problem that I suspect its either my turbo starting to fail or I broke some rings or valve seal/stems so want to ask...

If the turbo failed, should I get LOTS of smokes and ALL the time?

I'm going to have a leak down & compression next week but in the meantime...

a) I tested the scavenge pump & its keep up with oil flow.
b) No signs of oil anywhere unless its deep inside the muffler where I can't see
c) I checked intercooler intake & its dry
d) I seem to get smoke whenever I get on boost (ok - not sure if smoke starts when I get on boost or lift)
e) I can smell exhaust thru the window; not burning oil smell but exhaust
f) Car still pulls strongly

Any guess or suggestions before leak down test?

thanks!

[Ronnie's.930]

Well, given your description, I doubt it is the turbo. When the seals on mine failed, it produced sooooooooo much smoke (all the time) that you would have thought I was driving some kind of parade float (I'm talking fogging out an entire block behind my car) . . . much oil in the up/pipe, intercooler and such and also oil trickling out of the compressor housing . . .

R

[hoyabear]

Hobieboy,

I am dealing with, what I think is, a bad turbo right now. If you do a search for "worst day ever" or "oil scavenging problems" you can read a lot of detail about my situation. I just finished pulling it off and I am going to have it sent out to get checked/rebuilt if necessary. I am still not sure exactly what caused this to happen...I think it might have been a pinched crankase vent hose that pressurized the oil system and damaged the turbo seals...but the symptoms I have experienced are:

a) Oil in IC, intake, turbo (lots here) and elbow going into turbo from airbox, but no oil in airbox
b) Oil dripping out of blow-off valve, and from under center section of turbo
c) Oily smoke coming in through interior vents (during decel, when smoke is worst)
d) Some smoke at idle, lots of smoke while driving, TONS of smoke on accell or decel
e) Reduction in power and non-functioning boost gauge
f) Turbo still spools up (can hear it), but more slowly and with less effect

I checked the turbo after removal, and it still spins freely and there is no lateral play...although I still think this doesn't mean that the seals are not bad.

Anyway, from what I have experienced and read on these boards, it sounds to me like your turbo is not the most likely culprit.

[copbait73]

I have 36 years in turbochargers with Garrett and Schwitzer (now Borg Warner/KKK).

Here is a percentage to keep in the back of your mind. With passenger cars, 70-85% of turbo removals the turbo is not at fault. The aftermarket turbo business thrives on this, meaning they will gladly sell you a replacement or rebuild yours because by percentage the core you have is perfectly acceptable to place right back on your car. Usually if your turbo is truly FAILED they will give you a token core value then sell you a replacement (not rebuild yours) or UPGRADE.

I’ve instructed a 4 hour course on turbo systems and turbocharger specific fault diagnosis. It goes into great detail to fill the time and review almost everything under the sun. In the last 5 minutes I usually pull out a small mag flashlight and flat screwdriver and inform them we could have saved several hours by explaining the following:
90% of all true turbo failures can be quickly and easily detected by:
1. Using the screwdriver, remove the compressor inlet boot (usually very accessible).
2. Point the flashlight at the outer edge of the compressor blade. If you detect the blade is rubbing the housing the turbo needs replacement.
3. That’s it.

I won’t get into specifics expect to say there is a lot of talk about oil seals leaking. The “oil seals” everyone talks about are a combination of dynamic (flingers) and small piston ring gas seals. The point being they are not oil seals in the first place. If a condition exists for them to leak the causes are in descending order:
1. Restricted air-cleaner (dirty, oil contaminated, consumer/aftermarket mod related)
2. Engine crankcase pressure is too high (failed cylinder components, consumer/aftermarket modified breather system).
3. Oil drainage is inadequate (engine component or aftermarket mod related)
4. Turbocharger bearing failure (see above)

Hope this summarizes much of the anecdotal information.

[WERK I]

copbait73,
Thanks for the invaluable advice. Item number "2"; are you referring to turbo oiling systems where the turbo sump returns to the engine crankcase? If not, please explain.

[copbait73]

Dave:

Yes, item #2 applies to gravity drain systems, not Porsche's dry sump....unless you add a vent to the catch tank.

I suspect item #3 is at the core of many Porsche issues Plus, #4 (pictures I've seen suggest there are some modified turbos with inadequate bearing systems for their larger impellers).

[JFairman]

I know what the problem is, but if I tell the truth here my post will be deleted. That has happened 3 times now.
I'll just keep posting this when I see these posts and it's frequently.

The short version is DO NOT buy aftermarket hybrid turbos... unless you like replacing them frequently and supporting these folks, it is hit and miss with them.

The hole they drill to fit the larger Holset compressor wheel is rarely perfectly centered and dynamically balancing the individual parts at only 2000rpm like they do, does not cut it.

After dynamically balancing the individual parts the completed assembly must be balanced at 100,000~200,000 rpm on a very expensive VSR balancing machine if it is going to last as long as a factory KKK turbo, and your's is not.
I know, I've been through 2 of them. http://www.turbotechnics.com/docs/turbo/balanceinfo.htm
http://www.youtube.com/watch?v=-nbr0vepBkA
3 VSR turbo balancing machines exist in the USA.


///watching. . . . .

[hobieboy]

Guys,
Thanks for all the input... seems everyone also thinks that its not the turbo. I'll remove the inlet boot & muffler and take a look at the blade as copbait73 later today.

In some ways, I'm hoping its the turbo as otherwise, it likely means severe blow-by due to broken rings, valve stem seals, etc. A much more $$$ situation Hopefully the leak down & compression test next week will reveal more info.

I also checked the crank case vent - the drip tank & filter I installed are dry as well. If I have blow-by, that would/should be wet?

[RarlyL8]

You don't mention how many hours/miles the turbo has on it or how the car is used. For racing applications the turbo is considered a wear item and could be to that point.
If you are having no issues with oiling/scavenging you might borrow a good used turbo and a zork from a fellow racer and swap it in (removing the oily muffler). If it stops blowing smoke your old turbo was worn out.

[copbait73]

Originally Posted by JFairman

I know what the problem is, but if I tell the truth here my post will be deleted. That has happened 3 times now.
I'll just keep posting this when I see these posts and it's frequently.

The short version is DO NOT buy aftermarket hybrid turbos... unless you like replacing them frequently and supporting these folks, it is hit and miss with them.

The hole they drill to fit the larger Holset compressor wheel is rarely perfectly centered and dynamically balancing the individual parts at only 2000rpm like they do, does not cut it.

After dynamically balancing the individual parts the completed assembly must be balanced at 100,000~200,000 rpm on a very expensive VSR balancing machine if it is going to last as long as a factory KKK turbo, and your's is not.
I know, I've been through 2 of them. http://www.turbotechnics.com/docs/turbo/balanceinfo.htm
http://www.youtube.com/watch?v=-nbr0vepBkA
3 VSR turbo balancing machines exist in the USA.


///watching. . . . .

Thank you for the link to Turbotechnics. I see their "new" VTR machine infringes on my patent.

Marty

[hobieboy]

Yes - my car is 99% track use. So any moving parts are consumables...

I do have a zork so can try that. But borrowing a turbo would be difficult - there aren't that many around; especially one that is not used/on the car

Originally Posted by RarlyL8

You don't mention how many hours/miles the turbo has on it or how the car is used. For racing applications the turbo is considered a wear item and could be to that point.
If you are having no issues with oiling/scavenging you might borrow a good used turbo and a zork from a fellow racer and swap it in (removing the oily muffler). If it stops blowing smoke your old turbo was worn out.

[RarlyL8]

You don't need the same turbo, just one with same oiling requirements that is known good. If it stops blowing smoke then you know your current turbo has a problem.