knocking 606 - PeachParts Mercedes-Benz Forum

mdisav · #1 12-07-2005, 09:07 PM

Hi there. I have a newly acquired 96 E300 Diesel. I just took it for a ride and really got on it. Afterward it is really knocking and it does not sound good. It knocks as I rev it and slightly misses. These are pretty stout motors right. I hope something is not about ready to let loose. Any ideas of something that is not serious? I have put pressure on the front motor shock to see if it is bad and it still knocks while I have pressure on it. I also had the intake off so I guess maybe some egr gunk got sucked in. But would that make it knock or just idle rough.

Any thoughts are greatly appreciated.
Thank you.

mdisav · #2 12-07-2005, 09:26 PM

All is well. That was scarey though. I just took it for another ride and got on it again and it all went away. Something must have gotten sucked into one of the cylinders and I guess I blew it out. It sure did sound like it was going to throw rod though.

Hatterasguy · #3 12-07-2005, 09:40 PM

I have never heard of a 606 blowing up. Quite a few owners here use the pedals as on off switch's and can't hurt them.

Next time it knocks start cracking the injector lines and see if you can't make it go away.

barry123400 · #4 12-08-2005, 02:16 AM

Sounds like perhaps a piece of carbon broke away in the cylinder and your piston smashed it up after a little while and blew it out the exhaust valve. True engine knocks like rod bearings or main bearings as well as wrist pin problems etc. never can self heal. Pretty scary when carbon does this the first time. Remember years ago it really concerned me for a few minutes. Actually thought a rod was going bad.

DR.DIESEL · #5 12-08-2005, 11:22 PM

The ususal suspect on the 606 is carbon. The valve springs are pretty light
for those valves, and when you r&r the intake or plumbing, carbon can tumble down and get stuck on the valve seat. This causes a heafty compression leak and misfire.
The compression pops are what you are hearing..."knocking."

The non turbo 606's are cool, because you can sit there and watch them run with no intake manifold.
If you do have a leaking intake valve, finding it with the intake off will be easy, rev her up and watch for sparks getting past the valve. That will be your carboned up valve.

Beware of the busted chunks of plastic fuel line retaining clips. They love to fall into open ports when pulling the intake. That will be a BIG knock that does not go away when rev'ed up.

Regards,
Dr.Diesel

turbodiesel · #6 12-09-2005, 12:09 PM

I have similar symptoms.. Dr. Diesel.. how do you reccomend blowing out the carbon in the head? I cleaned my intake and EGR a few months ago.

DR.DIESEL · #7 12-09-2005, 08:18 PM

Quote:

I have similar symptoms.. Dr. Diesel.. how do you reccomend blowing out the carbon in the head? I cleaned my intake and EGR a few months ago.
Yesterday 08:22 PM

Well, with a few months of driving, the carbon should have gone away by now. It usually goes away after 20-30 minutes of driving. Quicker if you drive harder. You may have some other issue in there.
Does it misfire or stumble?
Possible bad injector or valvetrain noise.
Carbon will blast out of there with the first WOT full speed acceleration run in
most cases.
I hope nothing fell in there with the intake off.

Dr.D

turbodiesel · #8 12-09-2005, 08:22 PM

It only misfires on a cold start below 40F for about 2 minutes. But I have a very loud "injector knock".. It goes away while running diesel purge through the system, but comes right back on straight diesel.

Hatterasguy · #9 12-09-2005, 09:55 PM

John have your girlfriend start the car and start cracking the injector lines. When you trace it down to one injector swap that one with another and make sure the problem follows it.

Then just send that injector out and have it rebuilt, or order a rebuild from Phil. That way it will only cost you a couple of bucks to fix it.