hello guys, hopefully i have something like a bad/sticky injector here. here's the story

bought this 1983 300d back in march for <$500.

I have done a good bit of work to it so far such as:

new driver seat
new console wood
new console
some new vacuum lines
new pads/rotors
new wheel bearings
new water pump
new alternator and bracket
new fan clutch
all new belts
valve adjustment
changed oil 500 or so miles ago

im sure im missing something.

But now the car is making a funny knocking/ticking noise. no i don't have a video at the moment, but here is how it is.

-car has unknown mileage (243k on odo, odo is broken)
-car sat for 7+ years when i got it
-unknown maintenance history
-oil/coolant levels are good, the two aren't mixing, temp stays around 80*c
-noise only happens once the engine warms up, and when it does start, the noise starts very abruptly. car goes from running like a sewing machine to sounding like its about to fall apart
-very consistent with the RPMs
-sounds like it is around the top of the engine (maybe?) but does not sound like a rod knock (i may be wrong, considering a rod knocking or something of that nature is what i am hoping is not the issue )


This all began last night. I was coasting down my street at around 25 mph and then BAM it started making the noise. Ill try and get a video later.

The car still seems like it has power, but i will say, lately it has been running ever so slightly worse than before. under full acceleration, you can feel the engine kind of.. missing. it's like it loses fuel for just a split second and then keeps going.

the noise doesn't really get louder with RPMs, but it definitely is consistent with the RPMS.

What do you guys think? im hoping its anything other than having to tear into the engine.

maybe a lock nut backed off from my novice valve adjustment?

i've never worked on one of these before, so i was having some trouble doing the adjustment


any help would be greatly appreciated. i will post a video when i get a chance

I would bet on the valve adjustment, particularly since you said you were having problems with it. The best/fastest/cheapest thing to do is pull your cam cover and have a look.

The bottom end of the OM617 is virtually indestructible so that would be the last place I would look for trouble.

good to hear. im sure it wouldn't hurt to run some diesel purge through it either? it's probably never been done

It's an injector for sure - replace all 5 with new. Replacing the nozzle is easier, but then you have to have them set to PSI and pop tested.

Replace all, do a diesel purge and finish it with a valve adjustment and throw in a fresh oil change. You'll be laughing!

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1976 Mercedes 240D (Sold)
1985 Mercedes 300D Turbo Diesel: 500,000KM
1986 Mercedes 300E (Sold)
1988 Mercedes 300E (Sold)
2002 Mercedes C240 (Sold)
2008 Mercedes C350 4matic

A great site for purchasing industrial rubber products!

Industrial Rubber

https://www.youtube.com/watch?v=4WEVOghmxP8



pulled the valve cover, 1, maybe 2 valves were slightly loose but i dont think that would be the source of the noise.

side note: how the hell do you turn the engine over with the ps pump? when i did it the first time i had my crank pulley removed so i just turned it off of that bolt. my belt just slips when i turn off of the ps pump. should i tighten that belt a little? i got it moving by having a friend turn the crank pulley by hand from underneath the car while i was turning off of the ps pump but that turns into a hassle

i think im going to try diesel purge first, then on to injectors

thanks for the input guys

I would not try to rotate the engine using the power steering pulley. You need to remove the fan and shroud so that you can put a nice long wrench on that crankshaft pulley.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

oh but i am going to scream if i have to remove that fan one more time

I may be off base here, but the noise in your video doesn't sound like valves or injectors to me, that sounds mechanical...

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Rotating the engine by power steering pulley is fine. Tighten up your belt a little. I do it all the time for valve adjustments and so do many others. There are a few purists that advise aganst iit but it is a viable shortcut. Their argument is that it can "overtorque" the ps pulley nut. I call bullhockey on that. I put a torque wrench on it to check.

The same cannot be said for the camshaft nut. DO NOT USE IT.

SO, i ran two cans of diesel purge through the system, the noise is almost completely gone at idle, but is still just as bad when you give it some throttle. Im not getting any smoke, nor losing any power. It revs fine, so im still baffled. from my very novice past experience of catastrophic internal engine failure, you can usually tell when it is something serious either due to a severe loss of power, smoke, heavy misfiring, etc etc. this confuses me because the car still seems to run great. I still haven't gone and re-adjusted (tightened) my valves, if that doesn't fix it, i would hope it just needs the injectors cleaned or replaced.

Here is another video. sorry for the poor quality, phone was too low on battery to use the flash so i was trying to wield the flashlight. also, the consistant "rattle" you may hear is my air cleaner housing. two of the rubber mounts are missing

https://www.youtube.com/watch?v=0M6JSKI4O4s

It sounds mechanical to me too...wouldn't even conjecture as to what it might be though. If you say this showed up sometime after a recent valve adjustment, that's where I'd start. Whenever anything new happens right after something you've done, that's usually the first place to go looking.

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1983 W123 300TD US spec Turbo engine, with Euro bumpers and manual climate control, and manual transmission.

If it was rods, it would be losing oil pretty fast. I'd check the valves if anything.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

My car made a very similar noise a while back, hell it was worse.Skip to 1:50.
https://www.youtube.com/watch?v=WqLeQhujiyk


I reseated the injector bodies and it went away.

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

stupid question but, how did you go about that?

I believe that FoG means is that he pulled out the injectors, removed the old heat shields and installed new heat shields, and re-installed the injectors, seating them with the proper torque using a torque wrench.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC