Still sounds like a sewing machine. - PeachParts Mercedes-Benz Forum

winmutt · #1 10-01-2007, 12:07 PM

All the recent work on my engine is going to turn me into a perfectionist. Now that my car has decent prechamers I can actually hear the engine a little more clearly. Under load it sounds distinctly like a sewing machine. I have :
Adjusted valves
Replaced injectors
Fixed prechambers

Still makes the sound. Any other suggestions? As I said this is only under load and almost completely disappears when using bio. Injection pump?

#2 10-01-2007, 12:14 PM

I think what you are hearing is called "combustion".

Bio burns slower which results in less of a pressure spike when it ignites.

benzforlife · #3 10-01-2007, 12:39 PM

if u dont want sound coming from ur motor, then dont buy a diesel.
I f u dont want a pur/hum/beautiful clatter, then dont buy a mercedes diesel.haha

winmutt · #4 10-01-2007, 12:53 PM

Quote:

Originally Posted by ForcedInduction

I think what you are hearing is called "combustion".

Bio burns slower which results in a less of a pressure spike when it ignites.

Heh

. I hope so. I have to redo 2 of the prechambers, they are bubbling

. I cant begin to tell you how much better my car is. Time for a new muffler.

Anyways, this sound is unlike any other I have heard in any of the multitudes I have been in now. And it sounds literally like a sewing machine.

vstech · #5 10-01-2007, 02:13 PM

Hmm, ok you are familiar with Klatta... the sewing machine sound could be vacuum pump, cam followers, cam lobes, etc... look everything over real well.

lonewolftek · #6 10-01-2007, 02:32 PM

I'd guess either valve train noise (worn springs, cam lobes) or... how many miles on the new injectors? They may still be breaking in.

winmutt · #7 10-01-2007, 03:04 PM

Quote:

Originally Posted by lonewolftek

I'd guess either valve train noise (worn springs, cam lobes) or... how many miles on the new injectors? They may still be breaking in.

The injectors were slightly used (1k or so) injun rebuilds... Cam lobes looked ok to me (hardened cam).

Vac pump might be the culprit. I have the rebuild kit just havent gotten around to doing it yet.

tobybul · #8 10-01-2007, 03:15 PM

...... it might help...

pawoSD · #9 10-01-2007, 03:38 PM

Our 300D has a little bit of a sewing machine sound to it....when I was messing with the vac pump (testing its performance with a gauge) a while back, I noticed the sewing machine sound would change when I plugged the line or unplugged it....so I bet that sound is coming from your Vac Pump.

Our 300D will be going to synthetic here soon (within a few weeks) and we'll see if it runs/sounds any differently.

Monomer · #10 10-01-2007, 05:32 PM

"Nailing"

yes - sewing machine describes my car well also. It's in DIRE need of a tune-up. The engine has 421k on it right now, and the most work I know it's had is a head gasket at 380k.

I'm not looking forward to what this will entail; I'm starting with injectors and any fuel hoses that I can get a hold of.

These cars are bulletproof; This one been run at 120c before - not a problem (it was about a 15 miles trip...)

winmutt · #11 10-01-2007, 05:42 PM

Nope no nailing here. This is the same sound that was made on the old injectors.

Ara T. · #12 10-01-2007, 07:20 PM

Mine never sounded like a sewing machine, just a roar at full throttle.

A 300E i drove in did, however. It was a straight six though and revved to 6500 rpm or something like that though so I'd guess it would have a higher pitch.

tjseitz2001 · #13 10-01-2007, 09:20 PM

What kind of shape are they in? I had a noise kind of like that. A new set of belts fixed it, well at least that noise

. Just a thought. Tom 82 300D