W460 automatic transmission 720.xx

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ozzievito
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Joined: Fri 15 Apr, 2016 12:53 pm
Model you own: I own multiple different models

W460 automatic transmission 720.xx

Post by ozzievito » Fri 15 Apr, 2016 1:29 pm

First gear has a significant lag upon selection; it appears / sounds to be slipping as it attempts to pickup to gear; after a few seconds of hesitation there is a positive engagement and once engagement occurs there is no sign of slippage and old faithful will climb any gradient. Anyone have troubleshooting suggestions?

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kimrh
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Model you own: w126
Location: Perth WA

Re: W460 automatic transmission 720.xx

Post by kimrh » Fri 15 Apr, 2016 4:09 pm

Time for a full service with new filter and trans fluid.
Your can re-set those electronic trans to see if that helps as well
https://www.google.com.au/webhp?sourcei ... on%20reset

The electrical Conductor Plate in those trans is renowned for playing up and can easily be replaced (watch the MercedesSource excellent youtube videos on this trans and you will learn a lot without having to spend a fortune in a Service Shop by DIY yourself)
https://www.google.com.au/url?sa=t&rct= ... bs.1,d.dGo

Also watch this excellent video on the SONNAX valve body repair kit instal that does wonders to reviving simple wear & tear failure issues with this trans valve body-
https://www.youtube.com/watch?v=aOrLM4MpU4I
https://www.youtube.com/watch?v=vpQlnibuZdo

Also the electrical plug connector at the bottom of the trans is renowned for fluid leakage into the plug via the o-ring causing electrical issues - that is also an easy fix by swapping out the plug connector body in the trans case with a new one (not expensive) - worth pulling the connector to see if any seepage/dampness in there.
https://www.youtube.com/watch?v=8c7pDR83d_E

Also this video explains very well how the trans planetary gears work - very fascinating on how these great trans work for the layman to understand - Great watching
https://www.youtube.com/watch?v=zQwN2-9mLME
87 White Euro 500SEC "ECE" 195kw
88 Black Euro 560SEC 220kw
89 Midnight Blue Euro 560SEL hydro 220kw AMG Kitted
http://www.flickr.com/photos/krh2013/sets/72157632548663623/
https://www.flickr.com/photos/krh2013/albums/72157668572599252

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ozzievito
Posts: 3
Joined: Fri 15 Apr, 2016 12:53 pm
Model you own: I own multiple different models

Re: W460 automatic transmission 720.xx

Post by ozzievito » Mon 18 Apr, 2016 12:39 pm

Thanks kimrh - new oil and filter are the next on the to do list; also planning to check the B2 brake band piston for sticking and replace the seals / O Rings; the transmission is a 720.108 if anyone can point to a service guide. Will update once the above has been competed.

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ozzievito
Posts: 3
Joined: Fri 15 Apr, 2016 12:53 pm
Model you own: I own multiple different models

Re: W460 automatic transmission 720.xx

Post by ozzievito » Tue 26 Apr, 2016 1:48 pm

Removed the transmission filter but the sealing "O" ring that should be fitted to the top of the filter neck was nowhere to be found!

After an extensive search did not find anything resembling the missing item, I now believe that the "O" ring was not fitted last time the filter was changed at transmission service. Interestingly the work was completed by a "specialist" Mercedes mechanic. The attached image shows the filter neck where the “O” ring seal should be / is fitted – the oil was dirty and when the removed filter was disassembled (cut open) and the filter element washed in gasoline, a very small amount of fine metal was also found although this does not appear to be excessive amount of "silver".

I find it difficult to imagine if the “O” ring was not fitted to the filter neck at the last service how the transmission worked at all! Have I missed something?
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