OM616 idle clatter? - PeachParts Mercedes-Benz Forum

herring · #1 03-14-2008, 11:37 PM

I've only had my car about 2 months but have driven it to work every day (outside of days when it was snowing or single-digits in the morning).
It seems that during that time it has begun to clatter (if I'm understanding the noise correctly) at idle somewhat. After buying it I've had the valves adjusted, some engine seals replaced and I replaced the air filter. The mechanic said the timing chain looks good. The engine does have 307K miles on it but is continuing to run just fine. No odd behavior at all at speeds above idle. Oil level and pressure is fine. I am running it on regular dino fuel.
Is this a sign of problems to come? I did the oil cap test before I bought it and there was not much blowby at all. I ask because the car needs some rust-related bodywork done and I'm not sure I want to sink the money into this one if it's going to need an engine overhaul soon too.

t walgamuth · #2 03-14-2008, 11:44 PM

My diesel repairing farmers say if it has a good diesel clatter at idle the fuel is adjusted JUST RIGHT.

Whenever I have had a 616 or 617 adjusted by them it runs really well afterword and no difference in fuel economy.

Tom W

300SDog · #3 03-14-2008, 11:50 PM

I'm curious about the mechanic saying "chain looks good." Did he measure actual stretch? Sprocket teeth worn to fangs? Tensioner gone slack?

herring · #4 03-15-2008, 12:11 AM

Quote:

Originally Posted by 300SDog

I'm curious about the mechanic saying "chain looks good." Did he measure actual stretch? Sprocket teeth worn to fangs? Tensioner gone slack?

Well, I didn't pursue it. It was my initial experience with that place and my initial garage visit as a diesel owner. However, the place has been in business for decades, the last name of the guy who told me this matches the name on the sign, and they regularly have similar vehicles to mine in their lot.
He doesn't seem to be a verbose guy, but his summary of the car was that it had "had a lot of stuff replaced".
I don't know whether I'm becoming more paranoid reading these forums regularly or whether it is actually clattering a bit more in the 2 months since then. If idle clatter (absent any other issues) is no biggie then I won't worry about for now--took it out on the turnpike this morning and it performed like a champ (for a 240D automatic).

barry123400 · #5 03-15-2008, 01:02 AM

I have a couple of 240ds with really good engines. They do tend to as you describe it clatter at idle quite a bit. I just consider it normal.
I wish I could say all the engine noise totally disapears at speed with the 240ds but that is not so. Yet one is quieter at speed than the other.
The only self inflicted contributions to more noise I can think of is using thinner engine oil. Noise then would pick up. Or perhaps a load of different fuel might change things a little. Try a different fuel supplier for a tank of fuel next time. You do check your oil dipstick at every fillup yourself? With an older car it is a good habit especially. You can develop an oil leak at anytime.
On a long shot since you think the general din has increased check the air filter container. If the mounts break or get loose there is a noise increase under the hood.
Actually on volkswagons earlier diesels if that clatter was missing you knew everything was not well with the engine. Almost a case of more was better within reason.

turbobenz · #6 03-15-2008, 01:28 AM

maybe its a different batch of fuel you got, its very possible. Im guessing by varying the cetane rating you can make it clattewr or nopt, I know biodiesel doe not clatter AT ALL.

if it just started, its probably just your fuel

herring · #7 03-15-2008, 12:49 PM

Thanks guys--now that you mention it I really did notice it more this week--and I filled her up last weekend. It's probably just the fuel--that I paid $3.97 a gallon for. This was a major-brand station, too.
I don't necessarily check the oil at every fillup but do it periodically and did do it last weekend, it was fine...will try to do it at fillups. Thing is I haven't been shutting the engine off while filling. I carry two keys and for stops that only take a minute or two I've taken to leaving her idling, to save wear on the starter and everything else. I understand diesels use next to no fuel at idle anyway.
I will check the air filter container.

herring · #8 04-30-2008, 08:23 AM

I finally filled her up again a week ago and it definitely quieted down a bit. It still clatters but the "harshness" (don't know whether that's the right word) that caught my attention is gone. It seems it was the fuel.
Air filter container was tight (although like an idiot I lost the darn nut, the lid's just held on with the clamps now. Must have forgotten to put it on when I replaced the filter a couple months ago.)

dieseldan44 · #9 04-30-2008, 08:34 AM

A standard metric 10mm nut from your hardware store will replace that nut I believe.

Glad to hear you clatter subsided. Here in MA I have noticed clatter differences depending on where i get dino. Of course, bio makes the clatter go way down.

a local forum member has a 617 running on WVO and the sound difference of our two engines, mine on dino, his on WVO is remarkable. youd never believe they are the same thing...well his is a 951 and mine a 952 :-)

dd

Mark DiSilvestro · #10 04-30-2008, 10:06 AM

Miss Diesel, my automatic 240D (well thrashed by the PO's teenagers) seems to have a pretty loud idle clatter that diminishes somewhat after warmup. Beirut Taxi, my 4-speed 240D, is better, but my 300TD Wonder WAgon is the quietest.
In the past, there has been some confusing Forum discussion of a noise referred to as 'nailing', and attempts at cures by using Diesel Purge or replacement nozzles. Don't know if any of this applies to Miss Diesel but she's not my sole transportation, and in over a year it hasn't gotten worse, or blown up, so I stopped worrying.

Happy Motoring, Mark

herring · #11 05-05-2008, 12:18 PM

Quote:

Originally Posted by dieseldan44

A standard metric 10mm nut from your hardware store will replace that nut I believe.

Mine was 6mm. 46 cents at Home Depot.