John Deere 4440 Turbo Issues

On my 6700+ hr 4440, about a month ago I noticed oil around the intake manifold gaskets and around the coupling hose between the turbo inlet pipe and the intake manifold. I took the air filter to turbo hose off and pulled on the turbo shaft to see how much play it had. It had ~3/8-7/16" play, so I figured it was just wore out.
Ordered a new aftermarket turbo and turbo exhaust adapter. Got them in on Thursday (9/26) and put them on last Saturday (9/28). I ran a piece of rope through the return tube to make sure it was not blocked. Attached the return tube, then filled the oil inlet with oil and spun the turbo with my hand until the oil and had run through. I repeated that 4 times. Then, I pulled the fuel shutoff out and cranked the engine to double check that oil was coming through the supply line (since it was leaking into the manifold, we know lack of oil flow isn't a problem). Then I hooked up the oil supply line, and with the fuel shutoff out, I cranked the engine until oil pressure was showing normal on the gauge, pushed the fuel shutoff in and cranked the tractor. I let it idle for 30 minutes and it ran great. I then went to about 1800 rpm and let it run for about 10 minutes, then went to full throttle and let it run for about 15 minutes. It was then that I noticed it starting to smoke around the turbo. I looked around and saw some oil on the exhaust manifold, so I sprayed it off and kept watching. Then I noticed oil around the turbo inlet pipe again and oil around the compressor housing mounting flange. I turned the engine off, pulled the air filter to turbo hose off and checked the play on the turbo shaft. It had ~1/8" of play. All that done, I assumed the new turbo has a bad bearing/bushing in it and is just as bad as my old one. I took the new turbo off, and after it cooled, there is no more play in the turbo shaft.

Got another turbo in this week, and it is blowing oil out the compressor housing as well. One difference, this turbo does not have end play when heated up. I checked the engine oil pressure, and am at 50 psi at 1900 rpm, right at the top of the tech manual spec.

Am I missing something? Did I do something wrong? Any advice is welcome.
Thanks
Scott

I am no John Deere man! Just wondering if you
checked the oil drain for turbo to see if it was
plugged? Sounds like it maybe to me

Yes, the return tube is open.

I had read online that crankcase pressure can prevent the return tube from flowing on turbo applications. To test this, I ran the return line into a bucket instead of the oil pan. When doing this, oil was flowing fine through the return line, but was bubbling out of the oil pan feed thru that the return line would have went in to. So I unhooked the vent line coming off of the valve cover and the bubbling out quit, but the oil is still right there at the feedthru.
I would have expected that the oil would not sit at that feedthru. What would cause this? Is there somewhere other than the valve cover vent that I should check to make sure it is unclogged? How about the oil cooler? Is there anything there that can clog up and cause an issue like this?
Thanks in advance.
Scott

Your oil leak/ slobber could be from a weak injector .. giving you what we call "wet stacking" the raw un-burnt fuel mixes with the exhaust and looks like old oil..

When I have pulled the turbo off to test different things, oil is always dripping out of the compressor side of the housing. Would that still be from what you described?

Thanks

I really think I have narrowed it down to excessive crankcase pressure, but I am not sure where to start on that. I haven't found anything in the tech manual for that yet.

Any thoughts?

Thanks

No,, if you have oil on the compressor side it must be coming from the turbo seal...and it sounds like the first turbo had a lot of shaft play....with the second turbo there could have been residual oil in the exhaust side from the first turbo failure,,it may have cleaned up after running a while...

If anyone is interested, or in case anyone has this issue in the future and finds this post in their search for help.

Turns out the problem was clogged air filters.

I talked to an older diesel mechanic and explained what was going on, he said, did you check your air filters, I said no and asked why. He explained that when the the turbo is running at high RPMs that if there was a restriction in air inlet side that the turbo would suck oil through the seals as it tried to get more air from anywhere it could. I removed the air tube from the air filter housing and ran the tractor and that was it, no more oil leakage on the turbo.

One other issue that got solved from this was the the air flow sensor was replaced. Turns out it was bad and I was relying on it to let me know where there were air flow problems. Put a new sensor on with the old air filters installed and it lights up at about 1700 rpm. New filters installed now and the tractor runs great.

Scott

Technically the sensor detects pressure not flow.
Fooled me on this one. I had assumed that the tractor had clean filters.