Strange engine noise - Page 5 - PeachParts Mercedes-Benz Forum

MB140300SD · #61 04-23-2020, 09:34 PM

If you want to spend money you can pull it apart and have the crank turned. I think you can but I seem to recall something about these having some sort of special treatment that will be taken off if you turn the crank. Otherwise you can drive it till it blows up then put a good used engine in. Or, put the good used engine in now. This usually happens when they get ran low on oil. Not enough to lock it up but enough to take out a rod bearing, usually #1. I have ran across many cars over the years sounding exactly like yours.

yuke · #62 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 · #63 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 · #64 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 · #65 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 · #66 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 · #67 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?

Bigdaddybenz · #68 04-25-2020, 03:35 PM

Check your timing chain

ROLLGUY · #69 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.

yuke · #70 04-25-2020, 09:10 PM

Yes your right Rolly it was a wild shot I did check any way if I had any combustion gases in the coolant none showed up. Guess I'm gonna just face thats its a connecting rod bearing and pull the motor. Do you think it's possible that I could just replace the rod bearing w/o pulling the head just work on the bottom end if thats where my noise is coming from?

MB140300SD · #71 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

ROLLGUY · #72 04-26-2020, 08:48 AM

Quote:

Originally Posted by yuke

............... Do you think it's possible that I could just replace the rod bearing w/o pulling the head just work on the bottom end if thats where my noise is coming from?

Yes, read post #60(only if it is #1or2)

yuke · #73 04-28-2020, 04:49 AM

Rollguy I saw a while back you worked on a customers car that you had a lot of trouble establishing what was causing the knock which finally came down to the piston I think it was 1 or 2 suffered heat damage from low oil and made the piston a little egg shaped you got another piston new rings and were good to go
I'm thinking that is what might have caused my noise as when I drained the oil I was about 2 qts. low and that along with the rpms jumping up to about 4,000 when it downshifted might have had a starved oil area or spun bearing which to work on bottom engine comes out. Possibly has anyone ever had a broken valve spring that possibly my valve is not closing fast enough and piston is tapping the valve? Is there 2 spings that close the valve or just 1. Just about ready to start pulling it and put a doner in. It is strange that I ca'nt distinguish if the noise is comeing from top or bottom its a fooler.

Usaguy · #74 04-28-2020, 08:41 AM

Quote:

Originally Posted by yuke

I sure hope it did not blow a prechamber down into piston as I lost 1 engine already to that.

Quote:

Originally Posted by yuke

Just about ready to start pulling it and put a doner in.

the pain

ROLLGUY · #75 04-28-2020, 09:39 AM

Quote:

Originally Posted by yuke

Rollguy I saw a while back you worked on a customers car that you had a lot of trouble establishing what was causing the knock which finally came down to the piston I think it was 1 or 2 suffered heat damage from low oil and made the piston a little egg shaped you got another piston new rings and were good to go
I'm thinking that is what might have caused my noise as when I drained the oil I was about 2 qts. low and that along with the rpms jumping up to about 4,000 when it downshifted might have had a starved oil area or spun bearing which to work on bottom engine comes out. Possibly has anyone ever had a broken valve spring that possibly my valve is not closing fast enough and piston is tapping the valve? Is there 2 spings that close the valve or just 1. Just about ready to start pulling it and put a doner in. It is strange that I ca'nt distinguish if the noise is comeing from top or bottom its a fooler.

Yes, that was the engine that I fixed the knock by sanding down the rod cap. IIRC (it was a long time ago), that fixed most of the noise, but the piston was still the main problem. Not long after getting the engine running perfectly, it was ran out of oil. A turbo engine was then put in the car.