I thought it could have been exhaust when I first heard it bouncing off buildings and bridges but now that I have opened the hood I can tell it's coming from the engine.

After running a few minutes it quieted down a bit but was still there just audible over the engine.

It almost sounds like a steel-bristled brush running back and forth over concrete.

Just by locating it by hear it almost sounds like it's coming from an injector.

I don't believe you can adjust the valves on this engine. Is that correct?

I suspect something in the rotating parts on the front of the engine.

High pitched sounds are extremely difficult to localize.

OM603 has hydraulic lifters. No adjustments needed.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Check for something caught in the fan shroud. Then loosen the belt and see if you still hear it. Alternatively, trans flex disk. Everything vacuum working ok?

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I'll check that.

I did change out the fan clutch last weekend but I didn't hear the noise until today.

I used the ACM brand and I did hear somebody else using that brand that had issues with it making noises.

I'll double check to make sure the shroud is still securely attached and I'll give the fan a spin to see what I find.

Everything vacuum is still working as far as I can tell.

EDIT: I just went back out and I couldn't get it to make the sound again.

I did put my fingers on all the injector lines coming out of the pump, however.

Two of them seemed to have a much more pronounced impulse as felt by my finger tips than the other four.

They are the second and third lines from the back and they were "freestanding" meaning they weren't in any kind of bushing or holder like the others.

I'll just have to keep an eye on it to see if it intensifies.

Locks certainly do.

The sound is a metallic sound but a strange one.

It isn't high-pitched like a bearing or belt.

It is rhythmic and "wooosh, wooosh" or just "shhhhhh, shhhhh" sounds.

Did you see this recent thread? Does it sound like the video provided here:
Help diagnosing engine noise 87 300D Turbo

__________________
1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Unsecured injection lines will lead to failure.

Remember there is 3000 psi fluid in there.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I did see that.

The noise I had was nothing like that.

Now that I know what the inside of a fan clutch looks like the sound could have been made by the clutch plates sliding past each other.

I also have heard of another person buying the same brand fan clutch having odd sounds shortly after buying it.

I didn't get it to happen the last time I started the car but I have a feeling it will come back.

Well, unless something is missing I didn't see any bracket for these two lines.

They are to the injectors that are closest to the pump.

There should be small plastic clips that attach the lines to a bracket and keep them separate.

Failing to do this results in failure of the line. Either by rubbing between lines, or possibly cracking by flexing.

Jim

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Probably was the last part you changed out. Especially if you heard someone else had the same issue more or less. May be a break in noise of some sort that will go away.

Although I thought the linkage was just fluid driven. But you see clutch plates so it is a little more complex and could easily make noise. Did you check the fluid level? I thought I heard somewhere that they are to be stored in a certain position until installed but not sure. Dry friction plates only partially engaged would make noise for example. Was the outside of the case bone dry when you got it? I suspect you will have to verify there is adequate fluid in there.

Strange set up. Low on fluid and they slip excessively was my understanding. So they perhaps incorporate a combination drive coupling. Partial hydrostatic in combination with friction clutches. Although I have never had one apart to see.

Well in my haste, I actually ordered two of them.

I ordered the first one and found out after the fact that it wouldn't arrive for a week.

So, I ordered another one and had it to me in two days.

The one that got here first was the cheapest one and the metal flat spring on the front (whose purpose I don't know) was loose and popping out of one of his places.

The one I just got today was much sturdier and the flat metal spring on the front had some white adhesive holding it in place.

I suspect this flat spring flexes depending on temperature and causes the clutch to engage.

Since the first one was loosey-goosey I suspect that could be my problem but I don't know for sure.

The sound seems to be coming from the head/injector/injector pump area but it's hard to know for sure.

I'll do some more sleuthing this evening and tomorrow to see what's going on.

Worst-case I'll take off the cheapie and send it back for a refund.

There is a noticeable difference in quality between the two just from my visual assessment.

This is a big deal I know because on my 1993 300D I ignored the racket the fan clutch was making until one day it disintegrated and the fan blade broke free and bounced around in there poking a massive hole in my radiator.

Luckily I was in town and a mile or two from home.

UPDATE: I'm pretty sure the noise I was hearing was the bad bearings in my water pump.

It got worse and I replaced it today.

The engine has only a diesel combustion sound now without any screeches or shhhh sounds.