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Turbo Scavenge Issues??????

Last sunday drove the 87 930 home from California Speedway and the oil supply line to my turbo separated. The end fitting pushed the rubber line off the bead and mucho oil pumped all over the engine. I was a block from home and drove it up in my driveway and it caught on fire. Put it out with the garden hose and no real damage to the car. Luckily!

High pressure washed it to find the leak! Found the culprit and reconnected it with a hose clamp.

I put 4 quarts of oil in it and started it up and it ran fine. I drove it around alittle and when the oil temp reached 190 Degrees it started smoking like a forest fire.

I took the zork off and checked the runout in the impeller on the exhaust side and it had .030 plus play in it.

I took the turbo off and had it rebuilt. $550 dollars later I re installed it and prepared the turbo as follows

. Filled the oil supply tube (on top) with oil the connected the supply hose.

. Disconnected the coil wire and cranked her for 1 minute and had 20 pounds of oil pressure indicated.

. Started it up and let it idle for 15 minutes or so. No smoke!

Drove the car for a mellow cruise staying out of boost. Drove about 20 miles and got off the freeway and the car was idling for a while. Got stuck behind some slow trucks and all of a sudden the turbo was billowing smoke. oil comming out of the zork. Oil Temp was about 190 degrees.

Called a tow truck and towed it home.

When I drove it off the flat bed it didnt show a sign of smoke..Weird? but it was cold.

Started thinking about scavenge issues. I drained the turbo scavenge tank and did a pump check and it seemed to scavenge all the oil until it got hot~190+ then the scavenge couldnt keep up with the flow of oil from the turbo.

I saw another picture of a test that showed conciderably less flow than mine.

I cant find any data that states pump volume over time with a temperature coefficients.

Does this look like the right amount of oil volume at Idle.

BTW I took the ball bearing out of the banjo to the supply fitting and made sure it was there and reinstalled it. I didnt see a spring?

Does this flow at idle look excessive? The car doesnt smoke at temperature with the turbo draining as shown.

What do you fellas think? Bad turbo? Scavenge?

When you rev it up, it pumps 3 times that much volume. The scavenge is trailing the flow by about 5 percent and will eventually fill the drane tank and drown the turbo. It will smoke like hell. No smoke until that point!


Thanks

Bob






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Old 04-13-2008, 08:22 PM
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There is no spring to my knowledge at the oil supply line banjo assembly. Just a 8mm? ball to regulate flow volume.

Sorry can't help you with flow volume as I didn't have to check that before...
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted
Old 04-14-2008, 06:34 AM
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Quote:
Originally Posted by hobieboy View Post
There is no spring ...........
+1

Gosh, that seems like a lot of oil coming out of the sump! Is that at idle?
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'85 930 Factory Special Wishes Flachbau
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Old 04-14-2008, 07:22 AM
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Flow is at idle @190 degrees. It seems excessive. I think I'm going to put an orifice in line with an ID of .125-.150 to begin with and see what happens???

Does anyone know what the oil pressure should be at the turbo at operating temperature?

Thanks

Bob

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Old 04-14-2008, 09:55 AM
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What kind of turbo is it? I've had/seen trouble on 930's over the years with garret turbos. I'm not sure why but they seem to flow a lot more oil than a KKK and usually require a restrictor. Is it possible you had a restrictor that could have gotten lost upon turbo rebuilding? That happened to me once on a tricked up 930 w/garret, similar sump as yours while rebuilding the engine. It smoked like hell once the sump filled up. What can I say, I was young and dumb, now I'm just dumb...

The flow of oil looked about like yours FWIW... Nice pics BTW
Old 04-14-2008, 10:11 AM
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This is from another thread...look at his flow...it seems rather meager...


My turbo is a k27HFS



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Old 04-14-2008, 06:17 PM
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Wow, KKK huh? I wonder if when the turbo was rebuilt, did they maybe change the center section? Perhaps they used one from a Mercedes Truck or something weirder. I have a friend fighting a similar battle on a crappy homemade 935. It has 2 K27/29 hybrids, and 2 scavenge pumps separate from each other. One side works fine, the other flows way too much oil... they've been into multiple times by some German turbo guru down here. Looking into the drain hole the messy one looks completley different inside... Just a thought good luck!
Old 04-14-2008, 07:35 PM
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Not to insult your investigative work thus far, but here is a basic question. The ball bearing you inspected......is it the size of the ball bearing picture below?

If so, I would ship back the turbo to the rebuilder and state they did something wrong during the assembly of that turbo. IMHO, don't put a restrictor on the oil line. You would be treating the symptom and not the problem.
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'85 930 Factory Special Wishes Flachbau
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Old 04-15-2008, 07:44 AM
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Maybe there is a restriction elswhere in the oiling system before the pressure reference for the turbo and is diverting more oil to the turbo than intended?
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Old 04-15-2008, 06:26 PM
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What weight oil are you running?
Old 04-18-2008, 05:18 PM
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I am currently stripping my motor to fix a few oil leaks and noticed that the ball bearing was missing from my banjo fitting.
I am planning to put one in when I reassemble and need to know correct size. Its a bit hard to tell if it is 8 or 9mm from WERK's photo.
Old 04-19-2008, 06:18 AM
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Quote:
Originally Posted by billjam View Post
. . .when I reassemble and need to know correct size. Its a bit hard to tell if it is 8 or 9mm from WERK's photo.
8mm
Old 04-19-2008, 08:18 AM
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Guys,

Jim 2- I run castrol 40 wt.

It's been a few driving hours since I installed a .100 restricter. The Car runs fine. I took off the zork and check the play in the turbine impeller and it is about .020 full deflection meaning about .010 either way. I assume at this point it is OK, the oil has to flow through some size gap between the shaft and bearings. I tried to find the specs on this gap after breakin and nobody seems to know or have the specification.

I will continue to monitor the play...I did open her up and tried to abuse it this weekend. Just sling shotted on to the freeway and burned up some expensive gas..

This gas thing is getting crazy....Every excuse to raise crude prices. I think the devaluation of the dollars excuse is getting alittle OLD!

Bob
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Old 04-21-2008, 11:31 AM
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This turbo WILL fail with the restrictor in there. Your rebuilder couldn't have used the correct bearings hence your continued oiling issues.
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Old 04-21-2008, 07:59 PM
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The restrictor will hinder hydrodynamic flow to the bearing in the turbo. For those that havent heard that word before (it sounds funny) it is simply the film of oil that forms as a result of pressure entering the bearing and results in lubrication as well as centering the turbine shaft. It is very much like the principal that drives crank and rod bearings.
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Old 04-21-2008, 08:07 PM
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The restrictor will hinder hydrodynamic flow.....are you sure? Huh beats the crap out of me?
Isnt that the idea? Not one of you have entered a plausable PSI or flow rate that the KKK needs. This is mostly lore and gibberish. Hydrodynamically the shaft requires a few mathematical considerations, diameter and mass and supporting pressure (Viscosity). What flow rate and pressure will suspend the shaft for free rotation in a series of bushings that have a specific surface area. Do the math! .25-.30. diameter shaft (3.1416) will give you area circumference and calculated by a .75 bushing radially will give you ample suspension at 1 PSI at any temperature, this is a much bigger equation that noted but i think you guys are being to bleek. The flow is the same as a factory and may blow up and send shrapnel into my arse. But, I already made the mistake of having someone else rebuild it. $600 down the tube for a proprietary turbo. I will have it rebuilt again when it fails. Maybe...
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Old 04-21-2008, 11:16 PM
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40 weight oil is good, just need to make sure that you're not running water. I'd also ask, how old is your oil (probably relatively new from the amount you've added) since oil thins as it is used.

The turbo scavenge pump is positive displacement in sync with engine speed. Oil pressure is not. What is your idle speed set at? you may need to turn it up a little if it's really low.
Old 04-21-2008, 11:43 PM
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Dawg, dont get mad at me- Im not trying to see a fellow forum member get screwed by a blown turbo. Hydrodynamic flow is contingent upon volume, in where the turbine shaft clearance is supposed to provide the restriction in order to create the pressure. I dont want to see you pop the turbo, thats all. 1 psi is only enough to center it, not enough to keep it centered under load.
If I am wrong and your turbo lives a happy and prosperous life- that is great, but I dont think that it is going to.
As for a solution without the restrictor- I believe that it is Power haus that makes a high volume oil pump for the turbo scavange.
Dont get mad at Stephen or myself for not wanting to see you go through the agony all over again. I know this has got to be an aggrivating problem- Ive had similar issues.
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Old 04-22-2008, 06:04 AM
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Guys,

Maybe I'm just in denial....It hurts to blow $6 bills. I figure if it lives a short life I will know it soon. smoke...the ear retching sound of an impellers grinding away on the housing.. But like I said I have a zork which takes 3 minutes to remove and check the bearings. I wont let it blow. See fellas, I'm married and my wife is tolerant...to a degree. Another G for turbo repair will mean I will have to make this up big time and be over tolerant to her annoying habits.
I will have to go to church or something every Sunday for the next year. May be good for my stress level???

I'll be nice..

Bob
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Old 04-22-2008, 06:24 AM
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Comprimise is a pain in the @ss- I got rid of my girl before I got rid of the car.
Well all I could say is good luck and just keep an eye on it.
Oh..... tell her to go out with her friends for the night while you pull the turbo if it comes down to that. (hopefully not)
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Old 04-22-2008, 08:23 PM
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