Name that SOUND? Whats wrong with this motor? SEE VIDEO LINK - PeachParts Mercedes-Benz Forum

Dieselkraut23 · #1 03-10-2008, 07:19 AM

http://www.youtube.com/watch?v=G2ORFluGZAY

Dead on how it sounds in real life guys...it comes and goes but is like a rod knock and i know for sure its not a fuel knock.

DeliveryValve · #2 03-10-2008, 07:34 AM

What does it sound like when you crack each of the injector lines open?

#3 03-10-2008, 07:37 AM

Yep, probably a more advanced version of the knock my engine has. Best I can tell is its a rod bearing or piston pin clearance issue. I've done everything externally possible for mine but its been running great, even with the knock, for the last 5 years. Not many options beyond pulling the head and popping out the problem piston.

Listen to mine.
http://www.youtube.com/watch?v=QrjCgPfxj4g
http://www.youtube.com/watch?v=xMgVuGDf8xQ

MB-Owner-in-ind · #4 03-10-2008, 09:31 AM

Kinda hard to tell because the shakyness of the video but it looked like the knock was in conjunction with the valve train ie every other time the piston comes up. If this is true I would be looking for a loose tappet.

jcciem · #5 03-10-2008, 10:17 AM

http://www.youtube.com/watch?v=czV3fwZ73gc&NR=1

Youtube grouped your video with this one.

I can't stop laughing, it's very entertaining.

kerry · #6 03-10-2008, 10:23 AM

I also thought the knock was in the valve train. Sounded a little too tinny to be in a piston or rod in my opinion. I'd carefully put a mechanic's stethoscope on the moving camshaft in various places to see if I could narrow it down.

Cervan · #7 03-10-2008, 10:44 AM

I once had an engine that had a dead knock sounded metallic to no end. it turned out to be a bad injector and it was just purely nailing on that cylinder. Might want to check that out. Or remove the rockers and turn the engine over (Im not sure if the cam will hit the valves without the rockers..

Alastair · #8 03-10-2008, 11:22 AM

Defo worth checking out if its the injectors causing that knock....

My current DD W201 190D 2.5, I was convinced had a rod or piston-slap type knock, until I replaced the Injectors--its done 174K, so I thought it was about time.....

(It still has a hydraulic tappet/lifter knock when cold though....

)

My original old 300D OM-617 had a 'knock'....More of a 'nunk' type noise ,but that was just sheer old age and piston-slap at 350K miles. The engine was otherwise really quiet and smooth--Just annoying that noise....

It never got any worse during the near 100K I put on it, and will still run well (If it were in a car that is!)

Dieselkraut23 · #9 03-10-2008, 11:59 AM

Like i said guys its intermittent, totally smooths out for no reason then with out warning it will come back just like a switch was flipped......almost like rings crapping a sleve then smoothing the metal ...then catching again and scraping again.

Well for ****s and jiggles guys to help other people out today im gonna go replace all 5 injectors to see what it does.......the reason i think its the sleves/rings is i SWEAR for a lil bit i heard kind of a scraping sound but like i said it goes away.

ill keep everyone posted.

tobybul · #10 03-10-2008, 12:45 PM

Here I go again with suggesting syn oil (unless you are already using it). Its a cheap fix to start with and IMO does not hurt anything.

(Scares me to watch that video with the coolant line disconnected).

DeliveryValve · #11 03-10-2008, 01:05 PM

Quote:

Originally Posted by Dieselkraut23

.....eve then smoothing the metal ...then catching again and scraping again.

Well for ****s and jiggles guys to help other people out today im gonna go replace all 5 injectors to see what it does.......the reason i think its the sleves/rings is i SWEAR for a lil bit i heard kind of a scraping sound but like i said it goes away.

ill keep everyone posted.

Before replacing all the injectors, try cracking open each of the lines one at a time to while the engine is running to see if it has any effect. By doing so, you may narrow down the bad cylinder and help you determine what problem is. i.e. if the cylinder quiets down it could be a bad wrist pin, injector, pre-chamber or even a bad injector pump. If doesn't quiet down, then it would be bad rod bearing.

DeliveryValve · #12 03-10-2008, 01:07 PM

Quote:

Originally Posted by tobybul

...
(Scares me to watch that video with the coolant line disconnected).

It wouldn't be a problem to run is without any load for a short time. These diesel never warm up while in idle anyways, even with the coolant hose hooked up.

Dieselkraut23 · #13 03-10-2008, 02:13 PM

Quote:

Originally Posted by DeliveryValve

Before replacing all the injectors, try cracking open each of the lines one at a time to while the engine is running to see if it has any effect. By doing so, you may narrow down the bad cylinder and help you determine what problem is. i.e. if the cylinder quiets down it could be a bad wrist pin, injector, pre-chamber or even a bad injector pump. If doesn't quiet down, then it would be bad rod bearing.

I forgot if i did that or not.....if i crack it and it spudders(sp?) but still has the sound then yeah probely pretty bad.......still can not figure out how it can completely go away for different amounts of time then just come back, but then go away again.

If i give it more fuel it gets REALLY loud and REALLY scrarry.

vstech · #14 03-10-2008, 03:12 PM

notice the thunk is in perfect time with the #2 valves... I would start there.

Dieselkraut23 · #15 03-12-2008, 02:35 AM

OK guys adjusted the valves(they were all too tight) compression is at 355-357psi........after testing i poured tranny fluid in the motor oil and let it drip through the head to maybe loosen some crap if that was part of the prob.

Long story short the sound VANISHED! for a real long time this time too and perfect oil pressure. Then about 15-20mins later it came back and also the oil pressure was lower then the normal #2 mark so i checked the dip stick as it was running: NO smoke and very lil oil on the stick.

this motor sat and got rust in it and there is was very small amounts of rust on the cam lobes and dip stick.

so guys besides motor flush and changing oil over and over....how should i get the crap out and the what can i do BESIDES taking it all apart and manualy cleaning it?