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"Slipping clutch feeling" but in an auto car??
My sister in law has an A series Merc,(auto) and she is describing a problem pulling away that sounds like a slipping clutch, - revs rise with no road speed then eventually bites and off she goes.
Do these have clutches or is it done via a torque converter, I have no idea how auto transmissions work really? Also if anyone has any idea of the costs involved that I could pass on to her, that would be great. :) |
Have you checked the fluid level .You need to check it with engine running .
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Originally Posted by skinner
(Post 9209294)
Have you checked the fluid level .You need to check it with engine running .
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A class gearboxes are known to be weak and often break
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Originally Posted by what would scooby do
(Post 9209324)
A class gearboxes are known to be weak and often break
Surelu if the gearbox had let go then it would be mashing itself to bits, it drives fine from what I can gather after its managed to pull away. |
Yes low fluid levels can or else its probably the torque converter :( but either way if the low (possably low) fluid level hasnt been sorted for a while your probably going to have to replace the torque converter anyway :(
Tony:) |
i have just repaire a toyota that was finding it hard to get gear and then lost drive due to fluid loss through a rotten pipe to auto fluid oil cooler.Some auto boxes have a filter in this could be blocked if you ring mercerdes parts they will tell you if it has a filter inside the box .I have changed filters on mercerdes auto boxes before.
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Originally Posted by cookstar
(Post 9209341)
Surelu if the gearbox had let go then it would be mashing itself to bits, it drives fine from what I can gather after its managed to pull away.
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Originally Posted by TonyBurns
(Post 9209344)
Yes low fluid levels can or else its probably the torque converter :( but either way if the low (possably low) fluid level hasnt been sorted for a while your probably going to have to replace the torque converter anyway :(
Tony:) Ok cool, I'll have a check of the fluid then, will this be on a dipstick on the gearbox? Or is it another fluid I need to check, like I say I have never done any work whatsoever on anything auto. :confused: |
just like a engine oil dip stick that goes in to auto box.
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Originally Posted by skinner
(Post 9209366)
just like a engine oil dip stick that goes in to auto box.
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Originally Posted by cookstar
(Post 9209280)
My sister in law has an A series Merc,(auto) and she is describing a problem pulling away that sounds like a slipping clutch, - revs rise with no road speed then eventually bites and off she goes.
Do these have clutches or is it done via a torque converter, I have no idea how auto transmissions work really? Also if anyone has any idea of the costs involved that I could pass on to her, that would be great. :) Cookie, Promise us one thing. Whatever it is, you won't be working on it!! :nono: :nono: :p ;) |
Originally Posted by what would scooby do
(Post 9209355)
Good link that, thanks. :thumb: |
Originally Posted by Adidas
(Post 9210056)
Cookie,
Promise us one thing. Whatever it is, you won't be working on it!! :nono: :nono: :p ;) |
The gearbox let go completely the next day, first gear disintegrated, in the garage now having a £1500 rebuild. :eek:
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Actually to be pedantic, it will be the clutch pack for first gear that will have disintergrated. The lining material and metal particals from the failed clutch discs will contaminate the valve block and the rest of the gearbox, necessitating a total strip down, clean and replacment of all the seals, valve block, solonoids, actuators and other clutch packs. Running the gearbox low on fluid also does similar damage as the clutches are wet plate clutches (designed to be used in contact with oil), if the clutches run dry, the friction material quickly wears out (its only a few mm thick).
The physical gears used for first gear is also the same gears for second third and fourth etc. Sorry, just I find epicyclic/planetary gears fascinating with how they obtain different ratios just by using a few brake bands and clutches. Also give good insight in how a automatic gearbox works. :) Here's some of pics of a old BW automatic with a failed front clutch pack (used for 1st and reverse IIRC) that I rebuilt (click to enlarge): Sump metal sludge: http://i91.photobucket.com/albums/k3...h_109_0930.jpg Valve block seperator plate, more metallic sludge (all the black stuff is sludge - its a stainless steel plate): http://i91.photobucket.com/albums/k3...h_109_0939.jpg Metallic sludge in clutch actuator: http://i91.photobucket.com/albums/k3...h_110_1037.jpg The source of the metal (front clutch pack, one of the steel discs): http://i91.photobucket.com/albums/k3...h_110_1059.jpg What it should look like: http://i91.photobucket.com/albums/k3...h_111_1107.jpg The source if the sludge (one of the friction discs from the front clutch - whats left of it): http://i91.photobucket.com/albums/k3...h_110_1055.jpg What it should look like: http://i91.photobucket.com/albums/k3...h_111_1104.jpg |
Originally Posted by cookstar
(Post 9209280)
My sister in law has an A series Merc,(auto) and she is describing a problem pulling away that sounds like a slipping clutch, - revs rise with no road speed then eventually bites and off she goes.
Do these have clutches or is it done via a torque converter, I have no idea how auto transmissions work really? Also if anyone has any idea of the costs involved that I could pass on to her, that would be great. :) Told him to book it in for them to look at. He hasn't of course. :rolleyes: |
it might help to think of an auto box as a big hydraulic pump working at v high pressure
that is why fluid level (and quality) is important -- low = low hydraulic pressure hence slippage |
I guess she will have to be more carefull with checking her fluid levels in future then, thanks for the explanations as to the workkings of an auto box, I can't see the pics at the mo as work PC blocks them.
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