Noise level went down running on Diesel Purge, now noisy again - PeachParts Mercedes-Benz Forum

E_S · #1 05-15-2008, 12:13 PM

I ran through two cans of Diesel Purge last weekend. The engine sounded sooo smooth running on the diesel purge. I hoped it would last, but when I connected the hoses back to the diesel tank again, the noise came back and the engine is almost as noisy as before. I've heard other OM603 engines run very smooth, but my engine is not quiet at all..

Why did it run that much quieter on Diesel Purge?

rrgrassi · #2 05-15-2008, 12:29 PM

How noisy is noisy? Bio-D makes a diesel run quiter also, but that is due to lower BTU output of bio-D.

E_S · #3 05-15-2008, 12:36 PM

Well, too noisy?

Even when warm, it's as noisy as stone cold after the glow plugs turn off. Lots of clacking and typical "diesel noise", and it's not the fan belt tensioner or the valve lifters. As I wrote, it was running really smooth on the Diesel Purge, but is now back at the old noise level. Biodiesel makes it a little bit quieter, but still noisy. I will try recording it and posting a link to the clip here tonight.

rrgrassi · #4 05-15-2008, 12:46 PM

Which car and how many miles?

Have you had the injectors pop. pressure and spray tested?

E_S · #5 05-15-2008, 12:49 PM

The one in my signature, '92 300TDT. I live in Europe, which means it's a OM603.960 engine.

185k miles/310000 km. I have not had the injectors tested yet, but I think I'll bite the bullet, change the nozzles and have the injectors tested and adjusted.

Video soon to come!

Dionysius · #6 05-15-2008, 12:57 PM

Is the noise the infamous 'nailing' signature??? If so it may be caused by poor injector spray patterns.

Bajaman · #7 05-15-2008, 12:59 PM

I think the consensus is that there is more cetane in the diesel purge, and this is why people notice quieter running followed by more noise after switching back to diesel

E_S · #8 05-15-2008, 01:04 PM

Yes, it is the "nailing", I think. I have it on video now, just have to compress the video to be able to upload it somewhere..

tobybul · #9 05-15-2008, 01:10 PM

Quote:

Originally Posted by Bajaman

I think the consensus is that there is more cetane in the diesel purge, and this is why people notice quieter running followed by more noise after switching back to diesel

bjm, could you explain why cetane helps quiet it down?

E_S · #10 05-15-2008, 01:19 PM

Engine idling:
http://www.youtube.com/watch?v=S_hl2Mh7vco

Hatterasguy · #11 05-15-2008, 01:39 PM

Its not to bad, sounds like your injectors are not spraying as good as they could.

Yank them and have them tested, only fix as needed. The new nozzels are usualy of worse quality than the originals.

Bstef · #12 05-15-2008, 04:41 PM

Quote:

Originally Posted by Bajaman

I think the consensus is that there is more cetane in the diesel purge, and this is why people notice quieter running followed by more noise after switching back to diesel

That's my belief. When I've purged it was quieter as well.
Didn't see it as a symptom of anything.
Pretty sure you shouldn't either.

Dionysius · #13 05-15-2008, 05:23 PM

Interpreting noise is subjective.

Try this.

Get the injectors cleaned and tested at a shop (runs about $12 each).

Redo the video under as close a set of conditions to this baseline as possible. Car in same place, audio and video in same distance, etc.
Let us then compare.

If you have moved the problem and you have the need to know then run with lubro moly and redo again.

See if the clean injectors are same sound with and without the lubro.

LUVMBDiesels · #14 05-15-2008, 05:24 PM

The engine will run much quieter on DP due to the cetane level and I would expect the noise level to go up when yo are back on diesel. However, if the injectors were dirty, the DP should have gotten them somewhat clean. What color was the diesel purge as it was flowing back into the container from the injector return lines?

When I did my car, the DP was almost black coming back from the injectors. I ran two cleaning sessions (two cans each time) and got everything clean. My 603 is so quiet you can harely hear it at idle - not like my 5 cylinder diesels.