240D Ringing noise during acceleration
 

Gentlemen, I have learned a great deal from reading all of your insightful and interesting postings. Thank you!
This is my first "thread" so bear with me.

I recently acquired an 82 240D She's beautiful and I love her but there is a few qwerks here and there that need some tlc.

My question is: During a hard acceleration (which is most of the time, to keep from getting killed)

I hear a very faint ring-ting noise almost as if there were bells under the hood. But it is a very very faint noise, it would go totally unnoticed to average (non-diesel forum type) folk.

Would anyone be kind enough to lend and opinon?

Could it possibly be weepy injectors causing pre-ignition?

Now this is a new one!

I get a distinct sound at heavy load in the 220D, but it is more of a clank that a ringing sound.

You may have dead engine mounts that allow something to tap on something else (as in the air filter housing on the hood or something) under load -- there should be a rubber "bump" visible between the engine mount and the arm that goes to the block. The ones on my 220D were flat, and when I replaced the subframe bushings the AC compressor knocked on the fender. Quite a racket!

Peter

when my air filter housing mounts were bad (when I first got it from the PO, I replaced em the next day) it was prety obvious it was the housing making the noise because you could hear it through the firewall in the housing's general area. Also it only made a noise at idle, when the engine was under load it would kinda "float" there where it wouldn't bang on anything.


On my 300D there's a minor rattling when I'm accelerating from where the center heater vent door is (the door that directs flow when you turn the air on) but it's barely audible.

Is that what your talking about?

Use an additive
 

I had the same problem with my 240D, tinkered with it for weeks.
Than just did one ‘LubroMolly Diesel Purge’, an excellent cleaning agent. I think it comes with instructions, you just need a mason jar and some clear tubing.
After that I have used an additive with every fill up, 1/2 pint of ‘Power Service’, mixed with a bit of 2cycle oil.
You learn all this, just cruising this great forum. These guys an gals are a trip and have an enormous knowledge.
You get her going, mine is just ticking away.

Good Luck
Wolfgang

Some more suggestions.. could be "nailing" or stretched timing chain??

Thanks gentlemen for your excellent suggestions.

I guess I should have mentioned that the engine was rebuilt in Germany about 55,000 mi. ago (1994). I have paper work from the shop that did the work. Although difficult to read since I do not read German, but using general deductive reasoning of prices etc., I do not see anything that shows engine mounts were replaced, or injectors for that matter. I would assume that everything internal was replaced or remachined, ie. timechain, valves pistons etc.

Once again the sound is NOT: a rattle, vibration, clatter, kling, ding, klunk or anything of that nature.

It IS more of a barely audible: mutliple ring-ting only during hard acceleration. It is almost a musical like pleasant ring ring sound.
At the risk of opening myself to jokes, it is best explained as if you could imagine there were 1/2 dz miniature fairys under the hood ringing tiny bells! Go ahead and have a chukle, but I can't think of a better description.

My concern here, is that, if in fact pre-ignition is occuring, then unnecessary and harmful wear may also be occuring, (rod bearings, wrist pins etc).

I am inclined to use the "diesel purge" suggested by WOOFI
Is that designed to clean injectors & nozzles?

Assuming these are the orginal 1982 injectors with 177,000 mi. of wear on them. Would it not be prudent to just replace them with new freshly calibrated ones?

Or can I expect these originals to last longer?

Do MB diesel cars require intervals of injector maintenance? Or do we apply the "if it ain't broke, don't mess with it" rule?

fuel economy is around 27mpg, 75% highway 60-80 mph (additives include some cetane boost + shot of marvel myst.oil)


I know...... lots of questions. sorry. Any more coments would be greatly appreciated.

Thanks again.

PURGE IT
 

The 'Purge' did the trick for me no more ringing, it sounded in my case like wrong timing on a gasoline car.
I get consistent 27-29 miles per gallon, city and highway.
I also changed to schedule my fill ups only at a local truck stop, where I know the diesel is fresh, some ringing was audible after fill at random gas stations.

I think your model came with two fairies per cylinder. Their bells need to have the lash adjusted 's my guess.