1983 300sd 145,000 kms or about 95K miles.

I have this weird whining noise that seems to occur most often when the engine rpms are between 1500 and 2000 by the tach and the transmission is just about to upshift from 2 to 3 or 3 to 4. Once the transmission upshifts the noise seems to go away.

All I can say is that the noise seems to come from the passenger side of the transmission or the passenger footwell area.

No similar noise if you rev the engine in D or P or in D while holding the car stationary with the brakes. Only happens while the car is in motion.

Tranny has been regularly serviced and filter and fluid recently replaced. No problems with vehicle operation, transmission or performance apart from this weird noise problem. It is getting worse....

Any ideas?

Turbo whine?

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

If it was turbo whine would I not hear that with the tranny in neutral as well?

I think I only hear turbo whine under load. ?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Does it go down in pitch as you take your foot off the accelerator?

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85 300D 75K Anthracite Grey 0-60 in 13 seconds **For Sale**
84 300D 333K Black (The Velveteen Rabbit) 0-60 in 14 seconds
00 Toyota Sienna 208K (Sold)
15 Subaru Outback 43K
11 Subaru Outback 67K
98 Ford Taurus 100K (Gertie - Was Grandma's - drove it to church and shopping - really) Daughter's car now.
30 Model A Ford 2 Door Sedan (Sold) 0-60 in . . . Never reached 60

Yes noise either disappears or drops if (a) I take my foot off the accelerator or (b) when the tranny upshifts

When the tranny is in neutral you're not putting the engine under any load, you're just increasing the RPMs. The turbo will not spool up until you're actually driving and putting the engine under stress.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Does it occur right after an upshift? I had a horrible whistling/shreiking noise on my 85 300D. Turned out to be the Air Recirculation Valve by the turbo. Do a search on ARV or try to find previous posts by me. I put a BB into the vacuum line going to the ARV and the noise went away. Hope this helps.

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'85 300D 190K miles
running on B100 Biodiesel since 156K, SCRATCH THAT! I can only find Biodiesel at 1 location in Houston! (not very convenient)

No, the noise disappears as the transmission shifts up.

My EGR valve is already blocked off.

So if we suspect the transmission not the culprit and it may be the turbo - how do I diagnose that other than re-building the turbo?

I can hardly put a stethoscope on the turbo while the car is driving down the road to get it under load!!!!

I am having a hard time believing it's the turbo at so low a mileage.......

It doesn't necessarily mean your turbo is bad. Whines can be caused by loose connections in the air inlet.
Opening the wastegate and driving it might be a useful test.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I am not sure if we have the same noise. When I am going up a hill, and coming home I go up a winding hill that is about a mile long, I do not have any whining noise until I let off the accelerator. The first time I noticed it, I was traveling up a hilll in a wooded area with the sunroof open, at night, and I heard what I thought was some kind of screeching owl from the woods. But then I heard it again, and again and I thought, there cannot be that many owls out here. Then I realized that it happens when the car is under load and I take my foot off the accelerator. I find it interesting but have not worried too much about it. It seems like a rushing air noise and I thought it might have something to do with the vacuum system. It does not seem to affect the performance of the car at all.

__________________
85 300D 75K Anthracite Grey 0-60 in 13 seconds **For Sale**
84 300D 333K Black (The Velveteen Rabbit) 0-60 in 14 seconds
00 Toyota Sienna 208K (Sold)
15 Subaru Outback 43K
11 Subaru Outback 67K
98 Ford Taurus 100K (Gertie - Was Grandma's - drove it to church and shopping - really) Daughter's car now.
30 Model A Ford 2 Door Sedan (Sold) 0-60 in . . . Never reached 60

In looking at other posts on turbo whine I am going to pull the "u shaped" tube between the air filter and the turbo air intake next and see if that makes any difference. it will probably be the weekend before I can do that due to work commitments.

I'll also see when the inlet of the turbo is open if I can feel any play.

After that I will probably take it to my trusted indie as I cannot think of anything else to do to further isolate the cause between turbo or tranny.....

And the noise comes just before an upshift under mild to moderate acceleration to answer a couple of questions.

Noise gone, no need to replace the turbo

Turned out the new seal I put on the u-tube from the air cleaner assembly to the turbo was not seated properly. Clamp had worked a little loose and the jet engine noise had begun!

Re-installed seal, tightened clamp, problem fixed.

Cheers