Replaced IP Pressure Valve Seals- Now Have Injector Knock-Why? - PeachParts Mercedes-Benz Forum

ezrider · #1 02-26-2003, 07:07 PM

My mechanic replaced the the O ring and copper pressure valve seals on my 350 SDL resulting in a significant improvement in my rough idle condition, however, I now have a continuos injector knock noise up to about 1300 RPM.

I had an intermiitent injector knock before the seals were replaced.

Good news= much improved idle, bad news= injector knock (embarassingly loud). My mechanic used the three step 30 Nm, 30Nm, 35 Nm torque procedure when he tightened the seals.

What could be the cure for the injector knock noise?

Thank you.

CJ · #2 02-26-2003, 11:03 PM

They have to be torqued and retorqued in a very special way or else you end up with the problems you are describing. Look at the factory manual for specifics.

surfblau · #3 02-27-2003, 12:01 PM

Did you try and identify which injector? It should be pretty easy by opening each fuel line at the injector and seeing if the knocking goes away. Depending on results, you could test or replace the offending injector(s).

You could always try diesel purge- before or after.

alec

leathermang · #4 02-27-2003, 12:12 PM

CJ, That is SO true... I worry all the time about people using the forum as their primary source of information instead of an addition to the shop manual...
No telling how much damage has been done over the years due to this situation....

surfblau · #5 02-27-2003, 01:53 PM

It is not like I take my car to the shop, but if I did, it would probably be an independant shop because of the cost.

So, I was thinking- How realistic is it for an independent shop owner to know all the proceedures, for example, how to tighten the IP delivery valve seals on a 603?

It seems to me that a lot of "professional" mechanics would not use the shop manuals- since they may not own them all, or have the time to look up the correct proceedure. So they do a job the way they think it should be done, and the results speak for themselves.

I agree, the factory manual with this forum as an adjunct is the best way to go for do-it-yourselfers, but it sounds like the original post stated that he took it to his mechanic...who I doubt uses this forum.

alec

sixto · #6 02-27-2003, 03:45 PM

The procedure described is the procedure in the TDM or very close to it. Certainly the torque specs are right.

Sixto
91 300SE
87 300SDL
83 300SD

ezrider · #7 02-27-2003, 04:03 PM

I think I my have misstated my problem. What I'm hearing may be clatter. I'm not sure I know the difference between clatter and injector knock noise? Can someone describe both?

The noise I'm hearing is quite loud, opening each line at the injector decreases the noise a little (maybe by 1/6th). The noise sounds more like clatter to me than knocks. I know what a rod knock sounds like and it is not like that.

I had the noise intermittently before the seals were replaced, now it's there all the time at idle and up to about 1300 RPM.

My mechanic swears he used the correct torque procedure and I believe him, I even gave him a copy of it as it was quoted on this forum. 30/30/35 NM. He says there may be some air in the system that has to work it's way out. He did bleed the lines at the injectors. I think it sounds slightly better today, hope I'm not just getting used to it.

My injectors have 148K miles on them. They probably need to be rebuilt or replaced?

The good news is the idle is way better now.

Thank you.

surfblau · #8 02-27-2003, 04:48 PM

Delvac1 or Mobil1 makes the clatter virtually disapper after a couple thousand miles. I was impressed.

I bet all your injectors are fine. I once thought that mine were bad, so I had 5 of them tested at 220K miles. They were all ok.

I bet you are using dino oil.....

crf250r · #9 10-10-2004, 10:56 PM

30/30/35 Nm Torque ? Does this mean that you first torque to 30, then back it off, retorque to 30 and again back it off, then do a final torque to 35 ? Also what is 30/30/35 in foot lbs.

tomm9298 · #10 10-11-2004, 11:49 AM

Synthetic oil can decrease injector noise?

I have nailing or some noise at maybe #1 piston, replaced injector, ran Diesel purge, still noisy under 1200 RPM. When I crack the line the noise lessens, yet is still present. Could it be chain slap? All the threads I have read say Nailing is VERY LOUD, mine is loud but not deafening. Can nailing be in varying degrees of loudness? Sorry I have nothing to compare it to other than VW TDI's. And they are almost silent. It is not valve chatter, I know that noise. I want a set of balanced injectors for Christmas.... Santa, are you listening???