Slight jerk from Auto box

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ms500

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Jun 18, 2008
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When I move the gear lever from 'P' to 'D' or 'S' on my car, there is about a two second delay before it engages, and when it engages the car jerks forward a bit, it can be quite jarring if you rev the engine before it engages.

There is also a rattling noise when the car is stopped on the brake pedal and left in 'D', this goes away when I put it in 'P' or 'N'. Not really a problem, just thought it might be related

Otherwise, the box is very smooth and doesn't have any problems once it has engaged, it changes up and down smoothly through all gears.

Just a niggle really, does anyone know what this could be?
 
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Depending on how jerky you mean I know that a couple of auto's did this, as obviously the car is trying to move so you have to keep your foot over the foot brake. So might be normal?(ish). I never used to rev the engine as once engaged it could shoot off!
 
Mine has grumbled in D when stationary for since I bought it in Dec 06 16k miles ago. I changed the engine mounts which made no difference, have had the oil and filters changed without effect. I have no idea what it is, nor has anyone else who has looked at the car.. In all other respects the gearbox is fine.

Re the delay for selecting gear, mine takes a second - 2 seconds sounds a bit too long. Most gearbox issues are either ATF or vacuum system related. That's about the sum of my knowledge :eek:. Best of luck.

Ade
 
Thanks for the replies; I did have the gearbox oil pan replaced by MB recently because there was a small dent in it , so I would imagine they changed the fluid then.

It's not really a problem, just something I've noticed. It's silky smooth when driving.
 
The clunk could be a worn diff...

But it's much more likely to be worn diff mounts, worn prop doughnut, worn engine mounts or worn gearbox mount...

The delay is common with gearboxes in older W124s. I think it signifies wear (well there would be wear at that age and mileage) and perhaps low pressure from the gearbox oil pump

Nick Froome
www.w124.co.uk
 
>> The delay is common with gearboxes in older W124s

Up to about 3 seconds of delay is OK, beyond 3 seconds, and the gearbox is becoming worn - particularly if there's more delay in reverse.
 
It's probably a bit less than 2 seconds, more like 1-1.5 come to think of it.

The engine does rock very slightly when idling so it could well be engine mounts.
 

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