Hello, Sorry if wrong thread, I am new to this forum.I have an 1983 300d Mercedes turbo diesel with 279,000 miles. Been my daily driver for the past 10 years as if it was given to me by my great grandparents at 16. They purchased it brand new back in 1983. Today I took it out for a ride/2 errands. About 2 mins away from being home and suddenly the engine started making an awful clacking noise idk how to describe. It sounds like a semi truck. Car still drove with good power it was just the noise coming from the front of the engine it sounds like. I have a video but it won’t let me post the video in here. I suspect it’s either vacuum pump related or timing chain related? Injectors were placed with German monarch nozzles approximately 90,000 miles ago.If it was the vacuum pump though would the brakes, door locks, and other features on the vacuum pump not work? Thank you

I can try to share the video another way if anyone’s interested.

Take a small hose or stick and hold it to each injector one at a time to see if you can isolate it to one injector, it may be just that a bad injector. Check the air cleaner for a broken mounting bracket, this is common. Check all of the bolts one is big and the other are small on the harmonic balancer for tightness. Is there any chance someone put the wrong fuel in it?

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

https://youtube.com/shorts/M7m0g5ZfbAE?si=UoXAe_U_oymH4tEC

Hello,
I have already cracked each injector which made no difference.The air cleaner bracket is steady and not making any noise. The harmonic balancer appears to be tight and all. The vacuum pump is still workin. If it’s the timing chain or tensioner would the noise go away at higher RPM?Just put diesel in it last week when I changed the oil.

I posted a video of the noise on YouTube. The link is above, should be available.

https://youtube.com/shorts/M7m0g5ZfbAE?si=YK3A4HpBmB-RiNH1

Link posted to the noise my 83 300d is currently producing. Noise related to original post above

Hello,
Today I pulled part of the front end of the car off. I reached up into the crankshaft pulley/harmonic balancer to find a Metric Hex size bolt that sheared off and found another exact same bolt on the ground that appears to be in good condition still. With these bolts loose or missing is there any possibly of the risk of any metal components fall backing into the engine or a cylinder potentially? Still trying to figure out the cause of the noise. Shear pin?

No internal engine problems. Potential thread damage though to the bolt holes, this failure is relatively common. Get the broken pieces out, check the threads, get replacement hardware of Grade 8 or better, Loctite and torque it down and you should be good.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Hello.
Yesterday pulled off the belts, crankshaft pulley,large crankshaft bolt, harmonic balancer with puller after we finally were able to get one of sheared bolts out of the balancer to get the puller in.Got all the other sheared bolts out of the balancer and hit it with a thread chaser all looks good. Crankshaft seal looks good but am gonna replace it since we’ve gone this far. Is there any sort of gasket that goes down where the seal is held down by the u shaped metal plate? Or is gasket sealer gonna be my best option since it is a horizontal and vertical seal surface? Ordered new bolts and all the parts needed.

On the harmonic balancer there are 2 metal dowel pins that help hold harmonic balancer in place. Does anyone know the size of them and where I can find 2 replacements? I can’t find them anywhere. Thank you.

Have you pulled valve cover yet. Also note the dowell pins are not 180 degree apart. I may have a couple and will look in tool box tomorrow.

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Jim

I have not pulled the valve cover yet. That is gonna be a tomorrow’s task potentially I did notice that about the dowel pins If I can’t find any I figure that I would try to call Mercedes on Monday and see what they can come up. Every time I give them the VIN number they say the car shows up in there system as as a W126 but it’s clearly a W123 and even the original receipt for the car says W123.

2 things can happen here , the 6 small bolts that hold the pulleys are falling off , easy fix , in that case you leave the main crank pulley alone if the 27mm head bolt is tight .If it is loose , then you have a much larger problem , because then the crankshaft tip will be damaged .So if the 27mm bolt is TIGHT , leave it alone .

That exactly what happened. 3 of the pulley bolts completely sheared and 2 of them had back out.The sheared bolts we’re stuck good in the back of the harmonic balancer threads.The 27mm bolt was tight but in order to get the sheared bolts out and with the limited space the best way was to pull the harmonic balancer after marking them all. I plan to change the crank shaft seal while I’m at this point anyway. So far the end of crankshaft and everything looks good just still in search of the 2 metal dowel pins.

Are the dowels damaged, if not reuse them. The front crank seal can be tricky to replace as the lip of the seal can roll out of place as the balancer slides inward. I think there is a special tool for this procedure.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Oh yeah. I've looked in one place for the pins. Ive got another place I'll look tomorrow.

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Jim

Hello,
Apologies I have been away for several days out of town. I ordered the two metal dowel pins from my local Mercedes dealership for the balancer and I was surprised that they were the exact size of the old ones that came out. I did purchase a new crankshaft seal and the installation kit from **************.com. Made the installation easy though it did not specify how far the seal should go in. The seal sits flush but I am concerned the inner portion may be too far in or might rub on the chain/leak? That is my only holdup right now from getting the car back together. Will take a look at it again this upcoming week and give an update.

How much did the old seal protrude? I honestly think you'll be fine. If it leaks it would be from the inner lip having rolled over on the metal sealing ring.

Can you post a picture of any tool or device in the seal install kit? I'd like to see one, thanks.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer