Engine running rough and clanking.. :( - PeachParts Mercedes-Benz Forum

wilburtual · #1 10-09-2011, 07:35 PM

my 81 240D has been running fine up til this morning... when it started running a bit rough and now there is a little bit of clanking going on in the engine area.. its no too bad- i've read on the forum people talking about 'nailing' where it sounds like metal hammer hitting metal., its not that bad, just sort of a diesely clanking sound- i have a 77 240D that hasnt got much love from me yet, and it clanks a bit when it goes, so now my 81 sounds a bit like that. i also have a ford psd 7.3, same thing, has that school bus diesel clank thing happening..
BUT, unlike my PSD or the 77, the 81 is running rough with the clanking, so it seems to be more of an issue. its kind of an uneven chugging during idle rather than a smooth purr. almost like it might die, but it doesnt. it still gets up to speed on the highway, just feels a little rougher and a louder chugging & clanking noise when running.
i realize this is probably very vague,, and could be lots of things, but any suggestions on where to start? i for 1 want to make sure continuing to drive it isnt going to be harmful, and 2 how to get her back to a smooth purr.
i havnt done anything to it recently that would have changed things, or affected how it runs. i recently changed fuel filers, and topped off the engine oil. i havnt done a valve adjustment before, but have been meaning to learn how to do one, im not sure when the last time the PO had one done.

from what ive read around here, people seem to suggest injectors, IP, vacuum pump... ???

kerry · #2 10-09-2011, 07:39 PM

Best way to get opinions is to take a video, post it on YouTube and link it to the thread.

wilburtual · #3 10-09-2011, 07:40 PM

oh, yeah, forgot to mention, i did just notice that the braided injector hose returns is leaking near one of the injectors... not sure if that would cause anything besides a leak though.? any suggestions on where to get that braided hose? my local shops seem to just have regular fuel hose

wilburtual · #4 10-09-2011, 07:42 PM

got it, great idea. my GF has the car at work right now til late, but i'll take a video in the morning and post it to youtube/ link here. thanks for the suggestion

kerry · #5 10-09-2011, 08:18 PM

You can get the braided return fuel hose here by clicking on buy parts at the top of the page or lots of people get it at VW dealers since VW diesels use the same hose.

Zacharias · #6 10-09-2011, 08:55 PM

Quote:

Originally Posted by wilburtual

i've read on the forum people talking about 'nailing' where it sounds like metal hammer hitting metal., its not that bad, just sort of a diesely clanking sound- i have a 77 240D that hasnt got much love from me yet, and it clanks a bit when it goes, so now my 81 sounds a bit like that. i also have a ford psd 7.3, same thing, has that school bus diesel clank thing happening.

I wouldn't get too concerned. It's most likely a dirty injector.

But the video will certainly help.

surveyguy · #7 10-10-2011, 01:00 AM

top of my head even makes me wonder about 1 bad injector; basically one cylinder on strike.

wilburtual · #8 10-20-2011, 03:27 AM

so, the car started to run normal again for a couple days, now back to the rough running, clanky clank... here is a youtube vid with the rough idle and the clanking sound when running...

merc stutter.mov - YouTube

maybe dirty injector? should i try a diesel purge? or some other injector cleaner in the fuel..?

wilburtual · #9 10-20-2011, 04:00 PM

oh yeah, forgot to mention, when it runs rough like this, it has white smoke coming from the exhaust, where normally, it doesnt smoke at all.

kerry · #10 10-20-2011, 06:27 PM

That's an awful noise. I don't think it's nailing. Bad headgasket sucking water into a cylinder? Got a picture of the smoke, that might help.

wilburtual · #11 10-20-2011, 10:50 PM

i'll try to get a pic of the smoke tomorrow- it wasnt a super thick smoke, more like the kind i see sometimes when i first start up on a cold day. where it puffs a little out on startup and then goes away. where this looks similar smoke, but is more constant..

Zacharias · #12 10-20-2011, 11:34 PM

I don't want to stick my neck out too far but I've had that sort of noise from a dirty injector. I agree it isn't nailing but not all bad injectors nail.

My 85 300d nailed really badly when it arrived. It scared the living shinola out of me until it cleared up. It was the only time I've ever heard an actual sound like a ball peen hammer clanging on the head. Other times it was more like what I hear in the video.

You can try diesel purge as a troubleshooting step to see if it improves temporarily. But I would say that if it is a dirty injector, you would be better installing new injector nozzles than trying home or professional cleaning.

I am not a big believer in diesel purge as a cure-all.

Zacharias · #13 10-20-2011, 11:35 PM

Quote:

Originally Posted by wilburtual

my 81 240D has been running fine up til this morning... when it started running a bit rough and now there is a little bit of clanking going on in the engine area..

I should have asked right off the top: has the car been run on WVO at any time?

wilburtual · #14 10-21-2011, 12:04 AM

the car has been run on WVO in the past, -- why i was thinking it might be injector related... it is running on diesel now tho.

how do i know if i should replace just a nozzle vs the entire injector? i was thinking of doing the test of loosening each hard fuel line off one at a time while the engine is running to see if i can find a single injector culprit...

t walgamuth · #15 10-21-2011, 06:18 AM

Yes, that is the drill to locate the cylinder that is down if one is down. Then once the cylinder that is down is isolated you can swap the injector with another and see if the problem stays with the original cylinder or follows the injector.

If it does not follow the injector you have a compression problem most likely. Then it will be necessary to run a compression test.

Good luck.