Strange engine noise - PeachParts Mercedes-Benz Forum

fireman1073 · #1 04-21-2020, 09:10 AM

another engine knock post with video i never figured mine out. im still driving it

yuke · #2 04-22-2020, 12:39 PM

A fter giving this much thought and talking to a lot of mechanics I really believe I have a collasped lifter or faulty spring in one of my lifters because the noise started after the car down shifted on its own and rpms rose to about 4,000 traveling 65-70 mph. I really would like to try to pinpoint the noise to a certain cyl. by running with valve cover off and some cover to contain the oil fling while listening with stethoscope. Really thinking coming from 3rd cyl. If I can narrow noise down to certain cyl. how can I remove that lifter for cleaning and inspection or should I just put back together and run some marvel mystery oil through it and hope that fixs my lifter problem if that indeed is what I have? I'm thinking one of my lifters either has a broken spring in it or it is starved for oil and cannot reprime itself for some reason.

Usaguy · #3 04-22-2020, 12:49 PM

Quote:

Originally Posted by yuke

A fter giving this much thought and talking to a lot of mechanics I really believe I have a collasped lifter or faulty spring in one of my lifters

But you have the OM617 so there are no lifters

yuke · #4 04-22-2020, 02:20 PM

Oh guess I was watching a vidio for a later engine so I have no collasped hydraulic lifter so do I have solid lifters in my 617? Just trying to figure out what is causeing my noise from my valve area? There are spings on top is this this what returns the valve to closed position after it is open? Will still try to run it with valve cover off to pinpoint noise better Then button it back up and hope the marvel oil will clean out and lube whatever is causing the tapping noise. Forgive me as I have never worked on the internals of these 617 motors.

Usaguy · #5 04-22-2020, 02:31 PM

Quote:

Originally Posted by yuke

so do I have solid lifters in my 617?

Yes, if you can call them "lifters"

you're supposed to do a valve adjustment every 15k miles

yuke · #6 04-24-2020, 04:26 AM

Quote:

Originally Posted by fireman1073

another engine knock post with video i never figured mine out. im still driving it

I viewed the vidio fireman and your noise sounds exactly like mine I thought at the end of it all you figured out the noise was being caused by a prechamber that had a little hole in the bottom? Was I wrong in assuming that? I thought you had the bottom off and saw no wear or play on bottom end? This is my current noise.https://youtu.be/VZK9mjfZGEI

yuke · #7 04-24-2020, 05:38 AM

300 SD I respect your experience but do'nt you think the noise is a little high pitched to sound like a bottom end noise? I think if you look back at a posting fireman 1073 made he posted a vidio that sounded just like my noise and I thought he also posted 2 pictures of a prechamber that after pulling and inspecting it saw a small hole in the bottom of it and that was rattleing around in there causeing his noise unless I understood him wrong. Do the prechambers have any holes in the bottom just the sides correct? Was just wondering before I throw in the towel and yank the motor if maybe I should pull a couple prechambers and examine. I did have about 2 glow plugs that a bit of the tips were burned or broken off but they still worked.

vwnate1 · #8 04-24-2020, 01:51 PM

I can't offer any ideas about them except that I'd certainly remove all 5 prechambers, look for damage then crank the engine with them out to see if the noise changes or a tiny bit of crap comes flying out....

*Much* less work than replacing the entire engine .

ROLLGUY · #9 04-24-2020, 02:25 PM

Quote:

Originally Posted by vwnate1

I can't offer any ideas about them except that I'd certainly remove all 5 prechambers, look for damage then crank the engine with them out to see if the noise changes or a tiny bit of crap comes flying out....

*Much* less work than replacing the entire engine .

YES-Totally agree. Also, if you can get a borescope and have a look in the combustion chamber and top of the pistons, you should be able to see evidence of a piston hitting the head if it has a bad con rod bearing.

fireman1073 · #10 04-24-2020, 04:19 PM

Quote:

Originally Posted by yuke

I viewed the vidio fireman and your noise sounds exactly like mine I thought at the end of it all you figured out the noise was being caused by a prechamber that had a little hole in the bottom? Was I wrong in assuming that? I thought you had the bottom off and saw no wear or play on bottom end? This is my current noise.https://youtu.be/VZK9mjfZGEI

no i did not find the problem, pulled all the prechambers and all were good.
im leaning toward cam chain tensioner. i replaced nozzles, cleaned and inspected prechambers, cleaned inspected delivery valves, adjusted valves, removed vac pump replaced bearings in it, new cam chain tensioner spring, dropped pan and checked for any loose rod bearings and wrist pins and could not detect any play in them, oil pan spotless with no parts/debris, compression range from 380 to 420,harmonic balancer tight, flywheel tight, cam looked ok, rockers looked ok,chain at 4 degrees stretch, last thing here is the actual chain tensioner which i probably replace because if the oil check valves in it are bad it will not hold tension on the chain. After that im done

yuke · #11 04-25-2020, 02:52 PM

Could my noise be possibly caused by a blown head gasket? I ask because when I did pull the injectors there were at least 2 that were pretty wet down at the base. Should I do a leak down test on the motor? Like I stated previously the compression check showed 2 cyl. at 360psi. and they were side by side could that indicate a blown gasket inbtween them? Yesterday I ran motor which starts pretty fast and shot 1st marvel in the intake had no change of tap then I shot water in hoping if there was carbon buildup on piston head it would break it up no change in tap slowed engine rpm down to barely running no change in sound when I rev motor up pretty sure sound is still there but not as noticable. I have a feeling that if I go to pull prechambers out I will have a bear of a time as I still have an engine sitting on my garage floor that I never was able to pull the chamber out and think only way to get it out would be pull head from inside out. Would the Harbor Freight leak down tester be good enough to do this test?

ROLLGUY · #12 04-25-2020, 06:44 PM

Quote:

Originally Posted by yuke

Could my noise be possibly caused by a blown head gasket? I ask because when I did pull the injectors there were at least 2 that were pretty wet down at the base. Should I do a leak down test on the motor? Like I stated previously the compression check showed 2 cyl. at 360psi. and they were side by side could that indicate a blown gasket inbtween them? Yesterday I ran motor which starts pretty fast and shot 1st marvel in the intake had no change of tap then I shot water in hoping if there was carbon buildup on piston head it would break it up no change in tap slowed engine rpm down to barely running no change in sound when I rev motor up pretty sure sound is still there but not as noticable. I have a feeling that if I go to pull prechambers out I will have a bear of a time as I still have an engine sitting on my garage floor that I never was able to pull the chamber out and think only way to get it out would be pull head from inside out. Would the Harbor Freight leak down tester be good enough to do this test?

If the head gasket was compromised in any way, your compression numbers would be nowhere near what they are. Also, it would run rough and/or overheat.

MB140300SD · #13 04-25-2020, 10:30 PM

Quote:

Originally Posted by yuke

Could my noise be possibly caused by a blown head gasket? I ask because when I did pull the injectors there were at least 2 that were pretty wet down at the base. Should I do a leak down test on the motor? Like I stated previously the compression check showed 2 cyl. at 360psi. and they were side by side could that indicate a blown gasket inbtween them? Yesterday I ran motor which starts pretty fast and shot 1st marvel in the intake had no change of tap then I shot water in hoping if there was carbon buildup on piston head it would break it up no change in tap slowed engine rpm down to barely running no change in sound when I rev motor up pretty sure sound is still there but not as noticable. I have a feeling that if I go to pull prechambers out I will have a bear of a time as I still have an engine sitting on my garage floor that I never was able to pull the chamber out and think only way to get it out would be pull head from inside out. Would the Harbor Freight leak down tester be good enough to do this test?

No