1992 W124 diesel will not stop running off the key

EireJames

Senior Member
Joined
Jun 20, 2009
Messages
136
Reaction score
2
Location
Cork, Republic of Ireland
Your Mercedes
Jeep Grand Cherokee OM642 power
HAd to go home to Cork last night anb back again to Galway unexpectedly, the old lady performed faultlessly over the 240 mile round trip as I have become accustomed to her doing :)

However when I arrived back in Galway she continued to run with the ignition key removed, all gauges etc went to 0 though, rev counter, temp gauge etc, even radio turned off.

Some sort of vacuum hose / pipe somewhere I take it.

Funny thing is there is a chap viewing her this evening :shock:
 

Bolide

Senior Member
Joined
Sep 17, 2002
Messages
3,294
Reaction score
4
Website
www.w124.co.uk
Your Mercedes
BMW 525 Diesel Touring
There's a vacuum pipe off somewhere. This is a standard fault - do a search and you'll find lots of info on it

BTW The manual shutoff valve is between two of the inlet manifold pipes and has a red marker

Nick Froome
www.w124.co.uk
 
OP
E

EireJames

Senior Member
Joined
Jun 20, 2009
Messages
136
Reaction score
2
Location
Cork, Republic of Ireland
Your Mercedes
Jeep Grand Cherokee OM642 power
  • Thread Starter
  • Thread starter
  • #3
Cheers for that, central locking is still working along with everything else. Will have a look after work, hope it's an easy spot and fix, fingers crossed. Would have to happen before someone wants to view it.
 

wireman

Senior Member
Joined
Sep 20, 2005
Messages
2,632
Reaction score
3
Location
lancashire
Your Mercedes
nice 201 2.5D 1993 & very nice 129 SL500 1994
My 124's pneumatic capsule (on top of the injection pump) failed with the same result.
A vacuum is applied to it to stop the engine.

Prior to the capsule's total failiure my engine had developed the habbit of taking its time to stop and juddered sluggishly to a halt.
With its new capsule the hand lever stays down overnight untill the key is turned on.

A 4mm pipe runs from the servo pipe (some where near the front of the engine) to the ignition lock and another runs back from the lock to the capsule.
The vac system is connected together by rubber joints which can split and leak rendering the system a shade iffy.

On my 250D the pipes are brown to the key and brown with a grey stripe to the fuel pump.
If you have a vacuum gauge try lifting the pipe (brown/grey) off the fuel pump and connecting it to your gauge, when you turn off the key it wont stop the engine but the gauge should read at least 20"Hg.

Your central locking does not work of the engines vac system, it has a seperate pump.

The engine vac also drives your headlamp level adjuster, if this works the fault is probably confined to the engne stop system.

If you do change the capsule be sure to fit it correctly, it operates direcly on the fuel pumps control rack and miss fitting it could result in the pumps govenor being disabled and then once started the engine could run away, go over safe speed and self destruction of the engine will result.
 
Last edited:
OP
E

EireJames

Senior Member
Joined
Jun 20, 2009
Messages
136
Reaction score
2
Location
Cork, Republic of Ireland
Your Mercedes
Jeep Grand Cherokee OM642 power
  • Thread Starter
  • Thread starter
  • #5
Brown tube connection is broken where it taps into the main vacuum line, bad luck really.
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
47
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
good luck really. easier to fix than changing the vacuum capsule/bowl, they are a pig.
 

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
good luck really. easier to fix than changing the vacuum capsule/bowl, they are a pig.

On the earlier car you could have a piece of string from the red lever going into the cab,,and just pull the string to stop it :D
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
47
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
back in the days of trafficators and 2, 4 and 5 star fuel.
 


ALL MBO Club members qualify for 15% discount on second hand parts.Please see MBO Members’ Area for discount codewww.dronsfields.com
Top Bottom