Knocking Diag by Video - om602 92' 300D - PeachParts Mercedes-Benz Forum

johnmharte · #1 07-16-2015, 10:02 AM

I've been doing a ton of reading and watching of other videos for the "knocking" at idle sound. Trying to see if what I'm getting is normal.

This is my 300D/om602 turbo this morning.
https://picasaweb.google.com/113269285636978370799/1992Mercedes300D25#6172098210648443602
Here it is again from last night during a diesel purge.
https://picasaweb.google.com/113269285636978370799/1992Mercedes300D25#6171936610792593122
I do more racing/reving of the engine in the diesel purge video. The loud pinging at idle goes away above 1000-1500 rpms, which gives me some comfort.

Just wanted to check with the knowledge trust here. She has most likely 200k on the engine. I'm really thinking I should've rebuilt the injectors but wanted to get rid of some of the pre-chamber leaks and other issues first before going that big.

So, i've gone down to the injectors two times in 3 weeks just doing small things. I didn't do a compression test, see my other post about the adaptor not working and I didn't want to pull the glow plugs to test from there. She starts up quick without stumble.

History of work just completed, most recent first:
diesel purge
diesel kleen in the fuel (most of the time when I remember)
this month, pulled the injectors, new heat shields, cleaned, two diesel prechamber pulls to fixing one prechamber leak on #4. Intake cleaned/blasted, all new vac lines, shutoff valve new, cooling system re-worked, water pump, thermo, ect...
In short, a ton of catchup maintenance on a car owned by one of my neighbors that I bought.

All pictures and videos of progress here, well not all..but as much as I uploaded to share.
https://picasaweb.google.com/113269285636978370799/1992Mercedes300D25

I've read these threads as reference:
http://www.peachparts.com/shopforum/diesel-discussion/361611-clank-clank-when-cold-new-engine-time.html
http://www.peachparts.com/shopforum/diesel-discussion/370099-79-240d-ticking-new-here-well.html
http://www.peachparts.com/shopforum/diesel-discussion/369139-w123-knocking-sound-diagnosis-2.html

Phillytwotank · #2 07-16-2015, 11:33 AM

WoW! you've done a lot of work and it's looking good.

It doesn't sound too bad to my ear. Maybe a little bit of "nailing" perhaps a bit of lifter "tick" as well. You said " nearly warm".. is that what it sounds like after driving? does the sound change after it is FULLY warm?

Have you had the injectors rebuilt or have you just cleaned them? One of the best "bang for the buck" jobs that i've done on my diesels. especially the 2.5turbo. When i got the 2.5turbo it ran decent, not much smoke, had decent power but was LOUD as hell. when i had the injectors done injector man found that 2/5 injectors where basically non functioning.. almost no spray. With newly rebuilt injectors it's been excellent. Much quieter, zero smoke, super smooth and great MPGs.
I do also run regular high blends of BioDeisel which definitely helps with the smooth sound. When its on pure Diesel i do hear some light "nailing" sound untill she gets good and warm.

johnmharte · #3 07-16-2015, 11:41 AM

Thanks! Yeah, she was in a pretty bad place. Dead trans, past due on nearly everything.

I've done VERY little to the injectors. Just simple cleaning when they were out and the diesel purge. I also have some Liqui Moly diesel injector cleaner solution as well. I thought about doing one more "purge" with that solution as well.
I have no idea why I bought it or what makes it different from the Liqui Moly diesel purge solution.

I have the guides on how to take them apart, clean, lap, and then pop test... but I really really didn't want to do that. I'm sure we all know how the first attempt at a new job is, slow....

I'm thinking the same, next option is to send the injectors off to be rebuilt. I believe it is greeser in Columbia, SC that is here on the forums. I was thinking about tearing down, pulling one more time, and let him do his thing. I tried the injector o-rings first just to see if there was some kind of leak there that might cause some pressure issues... no big change.

As for the difference in temp. I'm about to take a 3-4 hour trip down to middle GA tomorrow and then on to FL if that goes well. I'm wanting to get a good number of hours on the engine after all that work... see if anything shakes out. I'll take another video then, fully warm after some highway miles. I don't get much over 60 mph around here in the small town.

Phillytwotank · #4 07-16-2015, 12:23 PM

Yeah. Highly recommend Greazzer. He's done all mine so far. Excellent service. His charge above the cost of the nozzles is very small compared to the cost of acquiring the tools for the job, learning the job and the uncertainty of first times and all that.

Phillytwotank · #5 07-16-2015, 02:04 PM

A quick clip of mine running for your comparison.

johnmharte · #6 07-16-2015, 02:13 PM

I'm dialed up to 11 compared to yours.

Similar sounding, I'm just stupid loud and much more tinny/metallic at idle.

I'm thinking injector rebuild and at that point might as well pull the glow plugs for compression testing.

johnmharte · #7 07-20-2015, 09:54 AM

https://picasaweb.google.com/113269285636978370799/1992Mercedes300D25#6173030211639984434
New video after running her for the first long distance test after all the work. That was about 4.5 hours, 65-80mph.

Only one little issue a new fuel return line was wanting to leak. Got that fixed along with new trans shift linkage bushings. That rattling was driving me crazy.

She is better after that run but not perfect. However, a family member heard about her and she is now purchased. I'm sure I'll be helping with various repairs still but she's one household removed now.

I also restored/corrected her paint last Friday before the weekend trip.