1995 E300D - 270,000 miles

This car has been on synthetic (Amsoil) its entire life. I bought from original owners two years ago. She has been mostly problem free but sometimes not super smooth. Especially at idle. What is crazy is that it starts up smooth when cold, but once it warms up for a few minutes, it starts making more of a pinging noise and runs a bit rough feeling with some shakes.

Just recently I replaced all of the plastic fuel lines with the updated ones. One of the regular rubber lines I did not replace as I did not have the correct line at the time. It was the main line from tank...I will replace it soon as it leaks a bit. The pre-filter and O-ring was do too along with the Delivery valve seal job. I see some air in the lines...maybe this is contributing?

Here is the cold start and warm up comparison:
https://www.youtube.com/watch?v=ayuMU_sV7Ao

This is the air in lines (which was filmed while it was starting up cold):
https://www.youtube.com/watch?v=vzWydX82YdI

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Maybe a little more information on ambient temperature, and how does it sound when at full operating temp.
The reason for asking is the after start glow cycle continues for a short while.

Sounds about like it is at shown at four minutes after startup. Never as smooth as the first couple minutes after it has sat overnight!

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Depending on ambient air temperature and engine coolant temperature, afterglow in this model can last as long as three minutes. However, with the OP and the car being in Florida, afterglow is not likely to last longer than a minute or so and probably is not related to the problem.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Couple of things come to mind. I have the same car, the air in the fuel line is definitely something to look at. The line from the tank can suck air and cause that also. The other is my car made a lot of noise at idle warmed and it was the belt tensioner shock completely worn out. Replaced it, greased the pivot arm for belt tensioner all quiet. Lastly you may want to run it on a can of straight Lube Moly Diesel Purge. It took away my cold idle nailing from injectors.

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1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)

After listening to that cold video I come back to belt tensioner shock. Once it warms up it looses it's compression

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1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)

Mine sounds the same way. 95k miles. Your front bumper looks exactly like mine as well. I call it "toothless".

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

It has a brand new belt tensioner on it but I will take a look at it again.

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

On that tensioner the damper (shock looking item) is the culprit when those make noise. Makes a crazy clack

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1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)

Had lots of noise coming from my vehicle and spent quite a bit of time changing out belt tensioner items until it quieted down.

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-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991

This might not apply to your vehicle, but its worth a look:

Alternator Pulleys 101: Clutch type / one-way pulleys

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96 E300d

I installed one of the clutched pulleys on my alternator at same time I changed belt pulley because of mileage. The clutch pulley quieted things down.

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-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991

I have the '97 NA diesel which I assume is the same engine you have. I have quietened mine down by doing two things. The belt tensioner shock will slap the head and also slap the bottom attachment. Pry between the head and the shock with a screw driver to see if the noise changes. My new shock made as much noise as the old one. I had to use a oil plug plastic washer to keep it from hitting the head. My engine really quieted down when I removed the black plastic cover over the injectors. I took it off to figure out which injector was nailing, and with the cover off there was no noise. I guess a fuel line was rapping on the plastic cover. I have spent years convincing the wife that diesels are supposed to clatter. Now it is so quiet she thinks something is wrong.

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'97 E 300 D

It is not the tensioner shock as I just rechecked it. And now I am getting a pretty rough idle with low power until I get on it a bit. It does just fine on the highway though.

I am thinking:

1. Check tank strainer
2. Check Pre-filter oring
3. Consider getting new injector nozzles

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Just with partial acceleration, right and at idle or loaded?
You could have the nozzles spray tested. I would place bets on one or more with a poor spray pattern. Other cause could be the IP but hope thats not a factor. I will consult with someone who is more knowledgeable than I and report back.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!