w124 200 auto idle erratic

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dragster425

Member
Joined
Sep 9, 2012
Messages
30
Location
HERTFORDSHIRE
Car
1993 200TE estate
My w124 200 8 valve auto idles erratically. But there is also a clicking noise from the area under the bonnet near the servo? The idle is normal for a while then the revs rise and fall to the point it may stall. When the revs rise they go to about 1300. The car is well serviced and looked after. The clicking has become more noticeable recently and still clicks after engine ha stalled with ignition on.......
 
Beside the servo is a long black plastic rectangular box. It contains the relays [ at the rear] and the fuses at the front. The front is accessed by removing the overcentre wire clips that hold on the lid. With this lid off the rear cover is accessed by the removal of several screws holding it in place--- you will then see the relays - I suspect one of these is clicking---- this might be a faulty relay [ in which case replacement/repair will effect a cure] or something causing it to go on and off - if it can be identified then you are closer to locating the fault.
 
The clicking seems to be coming from the area in front of that. There's 2 silver pot shaped things that I don't know what they are seems to be a water hose going to it
 
That's what is known as the duovalve it controls the flow through the 2 sides of the heater. There's a common feed in from the other side which branches internally to 2 sides of the heater-- there are 2 outlets to the two solenoid duo valves [the 2 silver cylinders you see are the solenoid coils] their outlets then join together to form a single return pipe [ the one you see] which goes back to the water pump. The duo valves are controlled from the heater control unit in the cabin- perhaps one of the duo valves has gone noisy? lots of posts about this on the w124 model on the forum do a search on duovalve
 
That's what is known as the duovalve it controls the flow through the 2 sides of the heater. There's a common feed in from the other side which branches internally to 2 sides of the heater-- there are 2 outlets to the two solenoid duo valves [the 2 silver cylinders you see are the solenoid coils] their outlets then join together to form a single return pipe [ the one you see] which goes back to the water pump. The duo valves are controlled from the heater control unit in the cabin- perhaps one of the duo valves has gone noisy? lots of posts about this on the w124 model on the forum do a search on duovalve

Damn......so that's nothing to do with h it. The emissions areok, I've had those checked
 
Other possibility is sticky /faulty motorised idle valve. It's fed from the OVP relay and controlled by the engine ECU. sometimes they just need a clean out with solvent. Try this for details of your M102 engine Untitled Document
 
That's interesting.I changed the ovp for a secondhand one when the car had starting issues and the abs light on the dash was on.it cued that but I've never been convinced of it
 

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