Strange noise from engine... - PeachParts Mercedes-Benz Forum

300SD81 · #1 05-02-2007, 10:03 PM

It hard to describe, sounds a little like metal lightly tapping metal, or maybe sliding against it. I might just be paranoid and be hearing things I don't normally though, was working on the alarm system and got a dead battery, kept thinking I hooked something up wring when the glow plug relay started buzzing.. There just wasn't enough power to keep it on. I also have all the center console, floor pads, and stuff out, so there is no sound insulation.. The engine was fine the last time I shut it down. Am I hearing things?

Hatterasguy · #2 05-02-2007, 10:04 PM

Turn up the radio. If its a real problem it will get louder so you can track it.

deerefanatic · #3 05-02-2007, 10:17 PM

ForcedInduction will probably pipe up on this.... His motor taps quite loudly.. But I believe it started out softly.........

Problem is, I don't think he's quite sure what it is..

300SD81 · #4 05-02-2007, 10:25 PM

I'm pretty sure its coming from the valve cover. Could jumping the starter with a screwdriver have damaged anything? Can I open the cover without getting a new gasket? It'll take at least a few days for one to ship...

Matt L · #5 05-02-2007, 11:45 PM

Depends on how old the gasket is. You can certainly reuse it and see if it holds, but get a new one on hand anyway. If it's old, it will likely leak. Don't try to seal it by tightening the bolts beyond specs.

t walgamuth · #6 05-03-2007, 05:40 AM

it sounds like you are probably listening a little more closely.

but keep listening. i dont think starting it that way can hurt anything mechanical.

good luck

tom w

Hatterasguy · #7 05-03-2007, 12:39 PM

I find with these old cars if you start listening to closely you start to hear all sorts of things. If its a serious problem it will get worse and to the point where you can track it down.

Your engine is not going to blow up. Your oil pressure is fine right? Fuel mileage is fine? Fires right up? Just drive it.

You can re use the valve cover gasket if its still pretty soft and not that old.

After spending a small fortune I learned to just turn the radio up, and live with the weird sounds that old cars make sometimes.

300SD81 · #8 05-03-2007, 02:51 PM

I made a recording on my PDA, the sound quality isn't good.. The engine definitely sounds different than before.

http://76.17.36.16/New%20Folder/Recording2.wav
http://76.17.36.16/New%20Folder/Recording3.wav

Play them in windows media player, the quicktime browser plugin on firefox that came up didn't sound right..

300SD81 · #9 05-03-2007, 05:02 PM

I think its getting louder,

http://76.17.36.16/New%20Folder/Recording4.wav

It seems to be coming from the valve cover, maybe loose valves? Should I try a valve adjustment? Or it might be the timing chain sliding against something, but I think it'd be a faster sound if it was the chain.

Adjusted valves.. Still making the tapping sound, ran engine with valve cover off and got myself oiled.. Everything looks normal

300SD81 · #10 05-04-2007, 06:13 PM

Anyone know what it is?

#11 05-04-2007, 06:59 PM

It's hard to tell much from the recording, is it coming from the area of the vacuum pump?

barry123400 · #12 05-05-2007, 07:41 AM

Most of us can relate to some degree. Perhaps it's stethascope time? Just the other day I walked under my last aquisition and heard some abnormal noise around the rear of the engine or torque converter area. It should not probably be doing it. Yet I too have learnt to wait and see. Thats if the sound is not too ominous. I will check from time to time to see if it is getting any worse though.
One time I was getting ready to tear a 617 down when the noise went away. Glad I did not tear it down. Yet mechanical noises should not self extinguish.
Perhaps these old diesels are a little special. I guess the exception to this is a suspect connecting rod or chain noise.

tami · #13 05-05-2007, 08:29 AM

possibly?

Hatterasguy · #14 05-05-2007, 09:00 AM

You can't really tell anything from the recordings.