OK, this might be vague, but I get a rattling/rapping noise (not valve related) from my 1978 300D's motor.

sounds like "tang tang tang tang"

Here are the symptoms:

especially prominent when not hot, gets a lot better once hot, but not totally gone

only happens when you are starting off, once you are going 40 mph or more, you can even flog it and it's smooth/silent/non existant.

could this be a cracked or damaged prechamber?

could a faulty, incorrect, or leaky injector cause this?

any thoughts appreciated!

280GE

So did this just start or did you just get the car? Most diesels "rattle" on start up. I got a new to me 240 the other day and the engine was rather noisy. Started easy, low millage, little chain stretch. I adjusted the timing this way and that, not much change, still noisy. I put in another set of injectors and that quieted her down. Have you checked chain stretch?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I've have familiarity with other diesel benzes, but have never heard this type of noise, definately not normal.

How do I check for chain stretch?


-ms

Dumb question, but how are your air cleaner mounts?

Is it definitely coming from the motor or is it from under the hood? Can you isolate where the sound is coming from? Last weekend I tightened the a/c compressor mounting bolts (I was even missing one) and it made the car a lot quieter.

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Fred Johnson
1977 240D
1983 300SD

Stevo, there is a pressure device which screws to the back of the oil pump I believe.... which ( of course ) had several updates over the course of the engine production... but which the manual suggests might be an easy cure for some of that noise....

Air cleaner flopping around due to broken mounts?

__________________
Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

"pressure device which screws to the back of the oil pump "

Greg.....Are you thinking rack damper, that wouldnt be on a 616 tho.

What hes describing sounds like nailing to me but could but could be the air cleaner mounts or something banging due to bad motor mounts like others suggested.

280GE

If I were you I would adjust the valves and check the chain stretch, do a search on timing chain. (oh, check that other stuff on the engine to make sure its not the air cleaner or AC as mentioned) Did you just get this car, or did this rattling show up all of a sudden? Do you have a manual?

Allot of glow plug problems this time of year. Do you have whiteish smoke with this rattling when you fire up?

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

nope its definately coming from inside the motor.

does anyone know what a cracked prechamber would do>?

how about if there are incorrect injectors?

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.....this program is not letting me be in charge of which photos I post.... LOL... HAL all over again...Close the air lock door quick!!!

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because i have the same noise and it sounds like valves. To me it sounds like, not being facetious, "rattle, rattle" and it really drives me crazy because I am really like this car and i would like to solve his.

I hope to adjust my valves this weekend. Recently i replaced my injectors which solved 70 % of my other problems and I don think this noise is injector related.

Its an irritating rattle you dont hear at full load, but during stop and go driving it is very prominent...if you have any further ideas, please let me know.

Thats a familiar sound on all Mercedes 123 300D's as the rubber mounts deteriorate and break off..I know that sound but thats not this one...

If it is a sound that seems to be at a constant interval, it could be the bottom pulley (that is bolted to the crankshaft) that has come loose, and is hitting the fan.

Take a look at that from under the radiator area. If that is the case, there r 6 allen bolts that hold the pulley in place. These bolts have been known to break or come loose.

The other problem could be that ur vacuum pump may be coming apart. If that is the case, u have to address this problem immediately. Parts coming loose in vacuum pump can cause alot of damage.

Hope this helps.