Friend just picked up a nice 1991 300D Turbo - he'd like to check valve clearances... how difficult is to do that on that car? I did the valve adjustment on my '85 300D but this newer engine looks quite different?!

Any advice -

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

there are no valve stems / valve lash to adjust like your '85.

the FSM mentions shimming the lifters, but most would just replace them.

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I'm pretty sure that the valves on that engine are self-adjusting.

I have one and that is my understanding.

I felt very lucky to have that added maintenance burden lifted after my W123.

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1993 W124 300D
-297K on the clock as I type this.

I see... well the car runs well - it's smooth when you accelerate and keep your foot on the pedal, but when it's idling it has a very pronounced 'clanking' or 'slapping' sound that's intermittent... I thought it needed a valve adjustment but that must not be it - what else could it be: rocker arms?! Hope that's not a really bad sign...

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Hydraulic lifters tend to punish one for poor oil-change maintenance.

Many here have had good luck with running Mobil Delvac 1 / Turb Diesel & Truck (synthetic) for an oil change or two to clean/quiet the lifters.

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Gone to the dark side

- Jeff

Harbor Freight sells an inexpensive Mechanics Stethoscope you can use to listen and find out exactly where the sound is coming from.
Check the sound in the Vacuum Pump area.
If yo do not want to buy a Stethoscope you can use a piece of Broom Stick or something else that conducts sound placed on the part you think is making the noise; put your Ear on the other end and listen.

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84 300D, 82 Volvo 244Gl Diesel

Very likely to be the belt tensioner shock absorber, the bushings go and it makes a clacking noise, but only at idle.

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1991 W124 250D - 130k Miles

+1 on the belt tensioner shock.

The cam rides directly on the lifters. No rocker arms.

Sixto
87 300D

The early 601 in the 190D 2.2 might have had shimmed lifters. Definitely not the 602 in the 91 300D 2.5.

Does it say if it's VW style shims between the cam and lifter or old Toyota style with shims between the lifter and valve stem?

Sixto
87 300D

I misread section 05-211. I quickly ran over it once a while ago and thought they were shimming for compensation when they showed the lifters disassembled. They are simply describing a refurbishing process to eliminate blocked passages which can cause poor lift compensation on 601, 602, 603.

Sorry about that.

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Tom -
Do you mean belt tensioner or chain tensioner?! Could you clarify?

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

(the whole serpentine belt Tension apparatus is plagued with potential failures!)
[Much,Much too complex]

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'84 300SD sold
124.128

Could this be the source of a metallic ping/clank I hear every time I shut off my engine?

At one point I was worried that it was timing chain slap until I measured stretch and found it in almost new condition.

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1993 W124 300D
-297K on the clock as I type this.

Is this the part/section to check for the belt tensioner: http://www.ps2cho.net/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/13-343.pdf

Man.... that's really complicated - not sure I would want to tackle that one... maybe time to take it to the mech.

Also, the car has a very fast shake at idle - if you're sitting the driver's seat with your hand on the steering wheel, it will vibrate your hand and your teeth... it's fast and furious...

Is this further evidence of problem(s) with the belt tensioner device?!

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Yeah thats right. Its actually very simple, only 4 parts:

1) There is the pivot arm (with included bolt) that screws into the timing chain cover. The bearing on this can fail, either partially by being rough to turn, or totally with it falling apart. This probably isnt a problem in your case, but check the bearing anyway.

2) The spring to provide the tension, not really a problem.

3) There is a shock absorber to stop the belt slapping around at idle when the power pulses are irregular. This fails a lot, the original versions had bushings which failed, and they also stop damping properly. 2 simple bolts to remove and replace, can probably do it without removing anything else on the om602.

4) The pulley, doesnt really fail, but the bearing went noisy on mine cuasin a high RPM whine so I replaced it.

Check the shock by holding it with your finger or a screwdriver. Replace it if your unsure, its cheap and probably getting worn out.

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1991 W124 250D - 130k Miles