MB E300 TDT is ticking/ having hard noises - Injectors?

[Preben]

My car (1998) E300 TDT is having this harch / hard sound. As far as I remember the 6er should run much more smooth. So I wonder if it can be a worn out injector.

It runs a little cold now, so I will exchange the thermostat. Some says that it running cold may cause the harch sound.

But I think it might be either an injector, or that is sucks air in the diesel returns (my workshop said that might be a problem).

Is there a way that I can check the injectors myself?

For the record: I also have problems with air in the fuel lines, and am waiting for spare parts. Can air in the fuel lines cause sounds too, or is the air somehow removed from the fuel before it goed to the injectors?

[Alastair]

Carefully and at the Injector, Slacken each steel-fuel-line in turn, then re-tighten.
--It helps to put cloth over/around the nut, as diesel fuel will be ejected in squirts...

IF the regular Knock/Noise goes when one is slackened--That cyl/injector is the problem.

Take care with the diesel-fuel that squirts out, it is under very high pressure and can injure you--Must use a cloth over the injector pipe-nut

ONLY do this test with engine Idling, and only long enough to identify if that injector is causing noise. Fuel force when faster than idle is very high...

[Preben]

My idle is around 500 reps per minute I believe.

So just remove the plastic cover on top, and then carefully slacken the nut on top - to release pressure from that injector?

[Alastair]

Yup--thats correct.

Its much the same procedure on any diesel--as well as your OM.606.

--Only issue with That engine, is the fuel ejected during the test may accumulate down the tube that the injector is down inside.

--Take care of thesmall rubber 'leak-off' lines on each injector, these can be easily damaged if the spanner slips....
--Easily replaced though....

--This can cause horrible fuel-smells for a while after the test which could come into the car, so may be idea to put some tissues down around the injector first before slackening off each line.

[Preben]

Thank you.

The "leak off" lines, are those the ones that goes back to the return diesel tube that goes to the diesel tank? On my engine these are put inside some sort of "textile". Probably for making it stronger?

Gonna be careful though. :-)

First need my engine running again. It suffers from air leak in the fuel lines, so yesterday evening I couldn't get it going.

[TMAllison]

Always fix the fuel/air leaks first on the 606, then tackle the other probelms.

Purchase new clear plastic fuel lines, or simply replace the orings on each line.

Follow this fuel path and note where air is first seen, replace every oring prior to that point.

fuelflow.JPG (image)

[Preben]

Yes, am waiting for the o-rings. The local Mercedes dealer wanted $8.6 per o-ring. So I ordered a set from another dealer that sells original o-rings. I tried with non-original ones, but that didn't work at all.

I am concerned however that I can get access to fuel line #3 on the above fuelflow.jpg without needing to remove the air inlet.

[Zulfiqar]

The O rings are standard metric ones. Make sure the lines are not too old, if they are brown even new rings wont solve as they can sometimes suck air from the barb nipple fittings.

Nailing is also caused by the injection pump having air in it due to leaky fuel pipes. It is also very good practice to replace the fuel feed pipe in the engine room, In your car its behind the washer tank and they do fail.

When you are positive that the system wont take any air, test the car for a few days then inspect the injectors, first with a stethescope and finally with loosening their feed lines.

[Preben]

Where can I buy these fuel lines? Hopefully cheaper than here.

They cost $60 per piece here...

EDit: Found them in the Peach Parts Store. About $13 / piece.