W140 Soft Close problems

AndyjamoS500

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Your Mercedes
W140/1998/S500
My 98 S500 usually a paragon of reliableness has been trying my patience for a couple of weeks

The boot/trunk door does not "suck" close as it should and the front doors refuse to close either (rear doors strangely trouble free)

I manage the situation by pulling & replacing Fuse #9 which re-sets the pump ecu and everything works again for about half a dozen closes of each

Im loathed to replace the pump with a used part as any on ebay for between £100 & £200 will be at least as old as mine now and will no doubt fail at sime stage

Has anyone tried replacing the pump ECU? the pump itself is actually extremley robust and should last indefinately its the 80's /90's electronics that seem to be letting the side down

Is my only option to fit a switch say to the side of the seat connected to fuse 9 and just flick it when it fails (it always works after the fuse us pulled)?

A new factory pump is £600 plus fitting


I absolutely love my car just completed a trip to the French Alps & back without a single blip thats 1750 miles on billiard table smooth french autoroutes & mountain passes, averaging 27 mpg
 

television

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Your Mercedes
2002 SL500, 216 CL500, all fully loaded
2 things on this, how long have you had the car, the soft close pump both sucks and blows, if the pump runs beyond 5 seconds you may have a leak.

If the car had been standing for some time then you could have moisture in the system, this is why the pump blows as well.

You do not need to replace the pump as what can also happen is the pump pressure can increase as it beds in, inside the pump, there is an adjusting screw that you can turn a touch to lower the pressure and put an end to pulling the fuse
 
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AndyjamoS500

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Location
Northamptonshire
Your Mercedes
W140/1998/S500
  • Thread Starter
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Ive had the car for a year and done over 20,000 miles its only been doing this recently & its used very frequently, i can hear the pump working when everything else is quiet but it only runs for a couple of seconds

I' try adjusting it

Many thanks
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
367
Age
89
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
Then the adjusting will fix the problem :D
 


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