1985 300D, approx 350,000 miles. I have a bird noise under load around 2500 - 3000 rpms.

This is not a single pitch whistle, but more like a warbling sound that increase in volume and pitch as rpms increase, then drops off after upshift or I let off the throttle.

I have checked the following:
Air filter hose connections
ARV - put nut under spring to increase pressure and disconnected vacuum
EGR - disconnected vacuum

My next check would be the inner and outer sealing rings between the turbo and the boost pipe. How likely is this?, or do I need to look elsewhere.

Thanks, Grezer

One member said his boost pressure went up after changing the Seal where the Turbo Outlet attaches to the Intake Manifold.
(Make up a spray bottle with Dish Soap and Water. With the Engine cold; spray it around the areas you believe that might be leaking and reve the engine and see if you get any Bubbles that would indicate you have an Intake Manifold Pressure Leak.)

Is this only a sound that happens while the Car is moving or can you duplicate it while the Car is satationary?

Sounds are hard to pinpoint and deceptive. Last Thursday my 300D was making a sould like the Transmission Flex Plate was rubbing on something. When I got under the Car I found that 2 Eahaust Pipe Bolts had come loose where 2 pipes join near the tail of the Transmission.
After tightening no more noise.

It could even be that Support Bearing on the Driveshaft, the Turbo Wheel/s rubbing on the Housing or just a slipping Drive Belt.

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84 300D, 82 Volvo 244Gl Diesel

When you disconnected the EGR, did you do it at the EGR or where the vacuum is split off from the main vacuum lines? Try disconnecting the main lines one at a time and see when the noise goes away. I had a similar issue with an 84 300D and I had to disconnect the EGR vacuum system completely (by the oil filter canister) for the noise to go away.

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mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)

Don't laugh, you might want to try placing a thick rod on the muffler exhaust tip. My whistle occurs when RPM's are between 2k-3k, 2500 rpm's to be exact.
Will happen when stationary or driving but always at the mentioned rpm's. Good luck.

I'll need to dig a little further, but so far it only occurs when driving the car, not when it's stationary. Also, it seems to be more load dependent versus speed. If I accelerate very gradually, I will get little to no noise. This would seem to eliminate driveline issues as the problem although I initially thought it might be a transmission noise.

That sort of noise can be caused by a slipping fan belt. I dont know if that helps.
Maybe you need to put a cat in the trunk & go for a drive !

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

I had 2 baby Robin's under the hood of my diesel last summer.

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

That noise sounds a lot like the one I had. I assumed (after a lot of searching on this site) that it was the ARV. I put a BB in the vacuum line going to it, and it quit. 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)

heh, I was thinking eagle screech!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

You know mine did too.

What happens if you remove the spring that you put in to increase the pressure? I bet that may be the problem.

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-Typos courtesy of my mobile phone.

I smell a bent tensioner spring.

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Matthew McIvor

2016 E350 4Matic Black/Black
2007 GL450 4Matic with Off-Road Pkg Silver/Black
1995 E300 Diesel White/Gray
1994 S600 Euro Black/ Black Velour
1986 560SL Blue/Blue/Gray
1986 190E Blue/Blue 93k

check the intake manifold bolts, sometimes they vibrate loose.