Judder when startup - diesel

johnw100

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Hi All

I bought a 2013 Mercedes-Benz B Class B200 CDI SE Auto a few months back and i`ve noticed recently that theres a quite a strong judder when the engine starts. Is this normal ? not sure if its the colder weather we have now or something is wrong.

Thanks in advance

John
 

whitenemesis

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How many miles has it done? Do you feel any additional vibration when idling?
 
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johnw100

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Its done about 44k miles. I had it serviced about a month ago.
There is a slight vibration at idle but as its quite new to me its hard to say whether its normal or not.
 
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johnw100

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No dont really feel anything when I drive, audible yes but i guess thats the usual diesel engine. Its just the initial turn of the key gives a 2 or 3 noticeable judders. Did seem to be worse until you put it into gear and release the brake.
thanks
 
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johnw100

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No its only really when you first turn the key.
Actually I just tried starting it and it was fine, but a earlier this morning when i went out twice and when i started there was a distinctive judder you can feel when starting the engine. You feel it through the seat.
 

grober

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Wonder if its a worn dual mass flywheel problem if the car has one?? If so I think it might be an engine/gearbox out job?
 
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johnw100

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wouldnt a worn flywheel show problems when driving though? this is just when I sometimes start the car there is a judder.
 

whitenemesis

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Worn engine mounts possibly.
 
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johnw100

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Worn Engine mounts i wouldve thought you`d notice something whilst driving though?
 

grober

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While not familiar with all the engine mounts on a B class but in most transverse engines the engine mounts have two functions one to support the weight of the engine and two provide an anti-torque reaction dampening effect. This would happen on engine start and stop and gearchanges where drive was taken up or released. You might not notice anything while driving along the road as the mounts/engine will have settled under their own weight into a stable position.
In the B class there are two main supporting mounts one at the engine front end and one at the end of the transmission. They are pretty complex assemblies in themselves but in addition there two extra anti-torque mounts referred to by MB as "pendular supports" 180+300 top and rear. I suspect one of both may be at fault? best checked up on a ramp. If you start the car in neutral [ I'm assuming a manual gearbox here] you may be able to discern excessive engine "rock" with snap opening of the throttle with the bonnet open.
 
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grober

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Says its an auto in the OP Graeme.
Mmm not sure if that would affect the snap throttle test mind. Might affect the Dual mass flywheel arguement tho- not sure. I'm still thinking engine " pendular supports" as likely candidates but as usual its just an educated guess from a distance.:dk:
 

Druk

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Mmm not sure if that would affect the snap throttle test mind. Might affect the Dual mass flywheel arguement tho- not sure. I'm still thinking engine " pendular supports" as likely candidates but as usual its just an educated guess from a distance.:dk:
Suppose you could be right but only if the swing ratio of the upstands has changed the support configuration :dk:. Is it possible the B suffers from the same gearbox mount fracture problem as the C63?
 

grober

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No idea on that one. I imagine the transverse engine setups are markedly different from the for and aft jobs. In terms of mounts I was thinking of the tearing [ or softening with oil] of the elastomer part of the mount rather than a fracture of the mount body or bracket but I guess anything is possible. A break might be more readily seen on inspection I guess.
Looking at WIS it looks like the lower pendular mount runs from the base of the engine/gearbox? to the front axle carrier crossmember/subframe. You would have to remove part of the engine bay lower cladding to inspect it.
 
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grober

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Added due to time running out on last post the newer B class appears to retain a front subframe of sorts and of course a dual clutch type semi-automatic box ?? :doh:

pendulum mounts,

Looking at WIS it looks like the lower pendular mount runs from the base of the engine/gearbox? to the front axle carrier crossmember/subframe. You would have to remove part of the engine bay lower cladding to inspect it with the added bonus the main engine and gearbox mounts should also be visible. The upper pendular support is much easier to see its just beside what looks like the radiator header tank.
 
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johnw100

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Thanks for all the replies.

Am in a bit of a dilemma in what to do next as this is my first diesel i`m not 100% sure its not just a characteristic of diesel engines.

I bought the car 2 months ago from a used car dealer which is about 40mins away and they said they will charge £80 to have it checked out and if there is a problem then they forward the problem to the warranty insurance company to see if its covered.

The other is to have a mercedes service centre which is 5mins away from my house but they`ll charge £120.

or I was thinking of finding another dealer nearby that has the same model and see if that has the same vibration/sound as mine. That sounds perhaps the first port of call rather than spending out money.

What does everyone reakon?
 

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