S124 300D 24v Not starting when hot.

Page may contain affiliate links. Please see terms for details.

trapperjohn

MB Enthusiast
Joined
Nov 19, 2008
Messages
7,306
Location
Lancashire
Car
124 300D 24V Estate
Perhaps not hot but lets just say is up to normal temp after a bit of a run.

Car a 21 year old diesel car suffer from CPS issues?

Car runs absolutely spot on from cold (after a bit of air works its way through the system) either on the move or in say a traffic queue. but will not start again if engine is switched off until it is almost stone cold again. Recent work includes new rubber on the stop valve and a service.

Any ideas most welcome. I thank you.
 
I had this issue with my C36 and it was the CPS, it was a nightmare of a job to do as well if I remember right.
 
I don't think a diesel of this vintage has a CPS. Not that I know what the problem is.
 
Jhon, the cps on your car only controls the rev counter and idle control system. It wont stop the car from starting when faulty.

Next time it plays up, try starting it with the fuel cap removed.
 
Not easy to reach John but try pulling the rubber elbow off the stop valve once engine is stopped, then try it. The vacuum needs to decay for the valve to return to 'run'. Might be a problem with the ignition switch which has the vacuum stop integral.

Just a thought.
 
My guess is that you have an air leak somewhere on the fuel supply which gets worse when hot. Did it start doing this right after the service? What did the service include? Anything on the fuel pre or main filter? Were the o rings replaced; has the pre filter been replaced and the o ring that goes with it? Any sign of any diesel leaks?
 
oops just read its a diesel. :doh:
 
Last edited:
So got a bit further with this.

I managed to start it by using my jump leads from the earth terminal on the battery to an earth on the engine block. Just a bare piece of metal on the block and that worked for a while.

But just when you need the car most this "frig" did not work. Most frustrating.

So rings local mate with multimeter and a bit more nous than me, sparky wise.

Long story short, a wire was attached to the solenoid on the starter motor with a crocodile clip, the other end of the wire was placed near the positive terminal on the battery but not yet connected. Check car is out of gear Switch on ignition. Touch positive battery terminal with other end of wire, BINGO. Starter motor whirs and she starts up fine.

We think. Its either the ignition barrel on the way out or the NSS (inhibitor on the gearbox) known as the Neutral Start Switch in American circles.

And to further compound and confuse the car now starts on the key after this exercise, but I dont see that lasting long. But at least now I have a way to start it.

The only other thing "new" that has happened to the car is a Parrot system was fitted a couple of years ago and this may be somehow introducing gremlins into the system.
 
Parrot - Handsfree Phone system which sometimes plays up in blocking out my radio when I dont want it to, when I have just started up. Fitted by an approved agent a couple of years ago.
 
Highly unlikely to be an issue.
 
Jhon, in the passenger footwell at the top right is a square 4 pin plug. The 2 large purple wires are the starter feed to and from the gearbox inhibitor, join these together to bypass it. Also near the battery where the heater pipe goes through the engine fire wall is a small 3 pin plug, the large purple wire goes directly to the stater solenoid so the car can be started from there.
 
Last edited:

Users who are viewing this thread

Back
Top Bottom