A diesel purge is not going to remove the small price of rock or dirt that ran thru your fuel lines, Polly from your old gas tank and got stuck in your injector, thus making the nailing injector noise that you speak of.

I real injector cleaning from a Bosch certified injector shop maybe will help. The only thing that will for sure fix it is to get new injectors.

You can also check which one is bad, I think, is to unscrew the top of each injector one by one while the engine is running until fuel is seeping out. When the nailing ticking noise stops that means the injector that is unscrewed at the moment is the one which is bad. If it's more than one u can still do this but u have to be systematic about it.

This method of finding the bad injector worked for me, please correct me if I just got lucky and if I'm giving bad info.

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Pretty much this.

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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.

that's sort of what i guessed but wasn't sure. Will try that when i get a chance. beyond ready to get this thing back on the road

ok, so now here is where i'm at.

i readjusted the valves, all of the exhaust ones were fine except one, but most of the intake ones were out of spec. there is one intake valve (3rd valve from the front) that i can't get adjusted perfectly because the nuts are horribly rounded off . i got it as close as i could, it is around .012 when it is supposed to be .004.

so buttoned everything up, and cranked it up, the noise was there but very faint. After it warmed up, the noise completely went away. 100% gone.

So i have been driving the car since Saturday. Probably have driven 100 miles or so.

Last night the noise returns. First just at idle, then up to about 2k rpm before it smooths out. no power loss. just the same annoying tapping/knocking noise


So you guys for sure think dirty/bad injectors? because that's what im leaning towards now

If the noise went away with a valve adjustment, it won't be injectors. If the valves were really off, it's entirely possible you need to adjust AGAIN. It isn't uncommon to have the valves need adjustment more than once in a short period if they're way off.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

SO here is the noise. Kind of hard to hear because i have my exhaust pipe off at the moment lol


https://www.youtube.com/watch?v=T94ZG5z39Ao


Car still runs great and barely smokes (blueish smoke)


but it does sort of "miss" when it makes the knocking noise.

The noise is only there around idle and i would say up until 2k RPM (guessing, my tach does not work) and it doesn't do it in park


im baffled now

well im honestly unsure what happened last night, but it didnt sound good.

i was backing the car up the driveway to start pulling the valve cover back off, when the car started making the same noise but much much louder, and also lost ALOT of power. Hopefully a valve did not drop or something of that nature

Don't panic, especially in front of the car. MBs can sense panic and for heaven sake don't let the car know you need it to run right away. Act like you don't care, at least when your in the presence of the car.

Do your crying inside the house and act as if life is good when you walk out the door.

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84 300SD
85 380SE
83 528e
95 318ic

^ ha. you are spot on with that.

i took my first two injectors out last night and man the second one is sad looking. very very dirty. i dont think they've ever been serviced.

if i buy 5 new monark nozzles, do i just drop them in the housings (after cleaning of course) and then im good to go? or what

Buy the new monarch nozzles and bring them to a fuel injection shop near you with the injectors. They will set the PSI/pressure, clean, decarbon and torque all injectors for you.

Also buy 5 new heat shells for your injectors, can get them at dealership. These businesses have $10,000+ equipment to do everything properly... you can buy $100-300 kits.. but you use them so rarely it's not worth the investment for a cheap piece of equipment.

Once the injectors are out and your heat shields are removed, clean very carefully with a microfibre towel with some brake cleaner on it. Spray a little bit around the injector area and clean everything properly. The new heat shines should be put in (make sure to put them in properly and not up side down) and then you can torque your injectors (70-80NM). I did 80.

Mercedes Injector Nozzle Replacement

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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

Hi, wondering how this went as i'm having injector issues as well. :'(

same noise, only happening when cold and touching the throttle. Noise goes away when engine has warmed up for a couple of minutes.

It's pretty strange as i've got about 5000km on the injectors since they were done at the shop, set to 145 BAR. And the fuel filters have about 2500km on them.

Any particular reason you have them set at 145bar?

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Hmm...

To be completely honest:

I purchased 5 new monark nozzles, cleaned/lapped all surfaces, torqued to spec, and dropped them all back in with new heat shields. Didn't get them balanced or anything.

About a month later, it started running terribly. Smoking, missing, sounded like knocking, etc.

After investigating a little, I found that the glow plug tips were all "melted" off, and one actually broke off inside the prechamber.

Piss poor decision on my part for not replacing them as soon as I got the car, especially since the PO told me he had to spray ether in the intake to get it started.

It basically pooled up in the bottom of the prechamber, and I was getting no fuel I suppose. The car actually still ran and drove. It became very apparent something was bad wrong when fuel was spraying out of the side of the body of the injector.

This ended up cracking the internals of the injector. The end of the nozzle was smashed in, bad, I assume from metal fragments flying around in there.

I purchased a new prechamber, new glow plugs, and a whole new Bosch injector, installed them, and haven't looked back since. That was 15k+ miles ago full of long road trips, offroading adventures, and daily driving.

I will say, I need to put a monark nozzle in one of my original injector body housings and have them balanced. Something just doesn't seem right about 4 original injectors with new monark nozzles, and one cheap Bosch India unit.

On cold start ups, the car sort of shakes and such, occasionally, for about 15-30 seconds. Nothing terribly bad. No smoking.

Hope this may help some. Let me know if you need any help. I am no where near as experienced and knowledgeable as most on this forum, I've only been messing with these cars for ~2 years now. But I am more than happy to share info in an attempt to help.

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'84 300D Euro 5 spd
'83 240D 4spd
'83 300D/5 spd manual/Lifted+28" AT Tires
'83 300SD
'10 E63

Parting out- '79 Euro 280TE Green/Green & '89 300SEL White/Grey

I had the same sound on my 300D...it sounded just like a rod knock and in the same area of the block...turned out to be a sheared flex plate bolt between the ring gear and the torque converter. Evidently, if someone has serviced the tranny and doesn't use locktite on the bolts, they can come loose or hear, and I'm telling you, you'd swear it was an engine problem! If you can, just pull the inspection rubber plate/plug at the trans, and have a friend rotate the crank to see if all the bolts are there...there should be a total of six in groups of two...worst case, at least you can eliminate this possibility...good luck!

Your car has a different speed related hum than any of the 300D cars Ive owned, but you say the exhaust is off.

The random knock sounds to me like an injector, Im in that camp.

Id lay off driving much until I got the injectors done. If it ends up being something much worse, a popped and balanced set of injectors can surely be sold for near the price of what you paid to have it done, so to me its a no brainer to get someone knowledgeable to do them for you...

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)