My 83 300SD has a very odd rattling noise I am hoping someone can help identify.
The car has 350,000 miles and runs very strong but recently a loud rattle / knocking noise at idle and up to 1500 rpm regardless of load has me puzzled.
I was able to identify where the noise was coming from by using a stethoscope with a rubber hose. It was the loudest when placed into the inspection hole between the engine and trans.
I took it to my local import repair shop and with the car in the air found a cracked flex plate and a torque converter bolt sheared off, never seen that before.
I was positive this was causing my noise since it was exactly where the noise was the loudest.
I had the flex plate and the bolt replaced.
Installed the flex and the torque converter with all new bolts and.......the noise is still there, just as loud.

Has anyone ever heard of the torque converter making a rattling noise?
It has been suggested that the torque converter has play either internally where the input shaft fits or in the front pump of the trans where the converter flanges engage the pump.
I have no drive-ability issues at all, the trans shifts as it has for the 7 years I have owned the car.
The fluid is clean and has a new filter.

It sounds like it could be the torque converter but it's hard to figure something like that out. You may need to take it to a good tranny shop and have them look at it. I've had torque converters out on Mercedes cars and they all sounded like they could have something loose in them but there was nothing wrong with them. I'm wondering if the guy torqued the torque converter bolts to the flywheel correctly. I had a car long time ago that had a knock when idling and would make a terrible sound after revving the engine. It turned out to be simply loose torque converter bolts.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

All bolts have been replaced and properly torqued. Also no apparent other damage was visible during R&R of flexplate.

Anyone have any ideas or ran into this before? I am stumped...of course that does not usually take much.

I hope they didn't replace the bolts with ones that are too long. They could bottom out and seem like they're torqued right yet still be loose.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

This is not a bolt issue. All new parts and bolts were purchased from the local dealer and properly installed.

Has anyone out there in this great forum ever had this happen to them or diagnosed this on one you may have worked on?

I think I have the same problem on my 300D N/A. I'm taking it to a local trans shop that does alot of vintage work in addition to newer cars. I'll let you know what they say.

Kevin

1978 300D
1979 240D

Yelllowbenz,
Thanks, I appreciate the help. BTW where in MO are you?

I live about an hour west of Columbia. Had planned to take the car in this afternoon but the snow changed my plans. Hope to take it in on Tuesday next week.

Kevin

1978 300D
1979 240D

My buddies '84 300d has a harsh rattling noise on idle also near the rear of the motor. We are figuring it is a cracked flexplate. Hopefully in the next month we are going to tear into it and see for sure.

Is there a way for you to post the sound. I am curious if it is the same sound.

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1983 123.133 California
- GreaseCar Veg System

Here is a clip of this noise, maybe that will help with identification. Listen for a mettalic clatter, rattle not normal for this diesel.

Attached Files

Benz_noise_1.wmv (62.7 KB, 1008 views)

It's kind of hard for me to hear it, but I almost certain that is the same noise my buddies 300d is making.

So let me get this straight...

Had a cracked flex plate/flywheel and one (or two) bolt(s) attaching to the torque converter sheered off.

The whole flex plate/flywheel was replaced and the you installed new bolts.

The question I have is, how were the threads on the torque converter? Were they stripped out?

This is helpful for my investigation on my buddies car.

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1983 123.133 California
- GreaseCar Veg System

That's my noise exactly. I don't see how it can be a flex plate as this is happening in neutral.

Kevin
1978 300D
1979 240D

The flex plate is what the torque converter is mounted to Kevin.

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Gone to the dark side

- Jeff

Thanks, I thought the flex plates were in the driveline aft of the transmission.

Kevin
1978 300D
1979 240D

I'm not sure what those are called, flex-disk?

__________________

Gone to the dark side

- Jeff