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Discussion Starter #1
Hi Folks,

After months of successful wrenching - thanks in no small part to the expertise here - I've hit upon a problem with the transmission that's well beyond my experience. I recorded a video clip of the problem I'm trying to diagnose and have uploaded it publicly to YouTube at:
. All feedback and advice welcome, but I'm especially looking for the three things:

1) Help me diagnose the noise. What has broken in my transmission?

2) So it's broken. What next? I'm curious about opinions on rebuilding my original transmission vs. sourcing a used one from eBay with marginal history, vs. sourcing an already-rebuilt one from a company like Adsit.

3) Any folks near me in Seattle, Washington have recommendations for transmission specialists?

More context: The car is a 1991 560 SEL with ~165K miles. It's in great overall shape. I think though a series of unfortunate events - my fault largely - triggered the failure. 1) I recently replaced all the vacuum lines and connections in the car, including the one down to the transmission. Unfortunately the transmission modulator vacuum line melted against the exhaust crossover, leading to zero vacuum and really hard shifts. I was in another part of the city and drove the car for ~25 miles this way before I was able to replace and re-route the vacuum line; the hard shifts may have done some damage. 2) It was time for a transmission service anyhow, so I did one, following the service manual and Kent Bergsma's instructions. I used high quality Amsoil ATF as replacement, new filter, new gasket, etc. I was very careful about not overfilling the transmission. 3) I had the old style pressure modulator so, at the same time, I replaced the modulator. I think it's the combination of these 3 things that over-stressed something. Since I did #2 and #3 at the same time, there was a short period of time where I ran the engine without adjusting the modulator, in order to bring the new fluid level up to the proper point. It was after this that I set the modulator pressure level, as shown in the video. That's also when the noise showed up... I did notice some small amount of metal particles in the old fluid when I changed it, so that's a pretty clear sign the transmission was on its way out overall.

OK, I think that's all that's pertinent to start. Thanks in advance for your sage advice!
 

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312 Posts
Not quite the scraping noise mine made before I had the trans rebuilt, in my case it turned out that the reverse clutches were worn completely out allowing the reverse apply piston to rub against the front drum, $3,000 later all is fine. On a side note even though the clutches were shot there was no delay or hesitation in the apply or operation of the trans.
 

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Premium Member
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Discussion Starter #3
Thanks for sharing your experience! I think regardless of the details, it's a bad noise from inside the transmission. My experience has been once you open a transmission up, you just rebuild the thing.

Where I have no experience is the wisdom of 1) rebuilding my existing box, 2) sourcing a good rebuilt box from a reputable place (Sun Valley Mercedes / Transmissions seems to be a leader), or 3) taking my chances with an eBay purchase that claims to be lower miles. I'm leaning towards one of the first two, choosing 1 or 2, with the deciding factor whether I can find a nearby shop (Seattle WA) that has a good track record with rebuilds.
 

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Discussion Starter #5
since the noise is there when the driveshaft is spinning you could have a bad center bearing on the driveshaft or something might be rubbing on the output yoke. check the simple stuff first
I hadn't thought about that possibility. Thank you! I can try to identify more specifically where the noise is coming from.

Sent from my moto x4 using Tapatalk
 

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W201, W212, W221, & W222 Moderator
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I had a somewhat similar noise that turned out to be an issue with the pump bearing having failed causing something to begin scoring the torque converter. New pump resolved the issue and the torque converter was still serviceable as the scoring was just superficial.
 

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Where I have no experience is the wisdom of 1) rebuilding my existing box, 2) sourcing a good rebuilt box
There is a guy on here in the for WTB fo sale section that was selling his recently rebuilt trans from his car as it got totaled or something. Then he posted that he was giving it away because he needed the space, but he’s located in NY. I forgot his handle on here. I’ll look it up and edit in a minute.He is member jac9f you may want to email him pm him.
Good luck.
 

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His name is Jack, this is his email address [email protected], contact him and arrange picking it up if still available.




There is a guy on here in the for WTB fo sale section that was selling his recently rebuilt trans from his car as it got totaled or something. Then he posted that he was giving it away because he needed the space, but he’s located in NY. I forgot his handle on here. I’ll look it up and edit in a minute.He is member jac9f you may want to email him pm him.
Good luck.
 
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