CLK500 (W209) stuttering and juddering under acceleration

[Garyhum]

I have a 2003 W209 CLK500 with 22500 miles on the clock.

Recently the auto box has felt very harsh when changing gears under acceleration between 40-60mph and then as accelerating the engine has felt like it stuttering and juddering.

I?ve now noticed on motorway journeys, even when the auto box must be in 5th gear at say 80mph, the car feels like its stuttering and juddering under further acceleration, even without any kick down.

Although I have booked the car into my local MB dealer for diagnosis I don?t have a great deal of faith in their fault finding skills.

Can anyone else on the forum offer a few pointers as to what the resolution might be?
:cry:

 

[GrahamC230K]

MAS sensor?

 

[piestore]

Hi

Mass sensor is certanly the first call but there have been issues with the coolant radiator (valeo rad only). If the dealer has a problem in solving this ask them to switch off the lock up clutch and test drive, if this solves the problem get an oil sample from the auto box and send it for testing as per MB recommendations. There was going to be a paper test kit avialable this is quick and simple but I don't know if they are avialable yet. If they do have to send it away it only takes a few days and you can drive the car in the mean time

 

[landover]

As above posts try the mass sensor.. :wink:

 

[piestore]

gerabox

Hi

Trust me, from the very good description of the symptoms I think this gearbox oil, has glycol contamination of the clutch plates, if the air mass fails to cure the problem follow the route recomended

 

[500sl]

Re: gerabox

Hi

Trust me, from the very good description of the symptoms I think this gearbox oil, has glycol contamination of the clutch plates, if the air mass fails to cure the problem follow the route recomended

Antifreeze on the clutch plates . heard it all now.

 

[piestore]

judder

Hi 500 sl

Whats your problem with antifreeze on the clutch plates?

The gearbox has oil pipes that run to the coolant radiator inside which is a heat exchanger if the heat exchanger is breached in any way this can result in ATF in the cooling system or coolant in the ATF, as the coolant pressure is higher than the ATF cooling system pressure in MB systems the coolant contaminates the ATF. As the oil in the gearbox runs at high temp the water boils away but leaves high levels of potassiam in the oil which is the indicator that there has been glycol contamination.

The fix is a new radiator,gearbox, torque convertor and flush out all oil lines. As you can see this is a very expensive fix hence the need for a complete diagnosis.

 

[Garyhum]

CLK500 judders and stutters

Well the car has been into Mercedes today and has been diagnosed exactly as Piestore suggested!!!

Basically the coolant mixture has leaked into the gearbox, and due to its corrosive nature the gearbox needs to be replaced (£1500), the torque converter (£700) and the radiator (£167). So a bill for near £2500 for the parts, plus labour, plus VAT courtesy of Mercedes UK without any quibble.

Apparently the local MB mechanic couldn?t find any fault stored in the diagnostics system, but then took it for a test drive and concluded the car was a disgrace. Then lots of frantic phone call to the MB technical team ? who seemed like Piestore to know both the cause and fix of the problem.

So far the local dealer has been superb, because the is classed as VOR all parts should be in for the morning and I should have the car back by tomorrow ? but I?ve asked them not to rush the job.

I?ll post again when I have the motor back.

But many thanks Piestore for your excellent diagnosis.

 

[piestore]

g box

Hi

Thanks for the feedback, glad you got it sorted

 

[Ger D]

Nice one Piestore, Impressed!