W124 300D 1995 starting

[Paul64]

Hi all,

I wonder if there is an adjustment to allow 'throttle-less' starts on my 300D 24v?
The car always starts, hot or cold, although it does take the tiniest amount of throttle to make it start after the glowplug lamp goes out - it almost feels like you're taking a small amount of slack out of the cable and cracking the throttle open a fraction of a mm but it's enough to make the engine start perfectly each time.
I would have thought that the fuel pump would have done this itself with a start-assist actuator - is there an way of dialing a little rack movement on starting with an external adjustment?
It's no big problem obviously as the car runs fine, but I do hear the Mrs try starting the car in the mornings and it either lumbers into life eventually without throttle or, starts with a stomach-wrenching increase in rpm if she pushes a bit too hard on the pedal, which doesn't seem right either....!

I look forward to hearing thoughts on the problem,

Thanks


Paul

 

[3 phase]

What about the adjuster on the linkage just above the manifold Paul, can't you take any slack up there? Surely someone more technical will be on soon but that's what I would do first and then try it.

 

[Paul64]

Hi 3-phase,

I would think the pump should start with no tension on the linkage - zero throttle position, but perhaps I'm wrong?

Paul

 

[mejermy]

I wonder if this could be a slight leaking back of diesel due to incomplete sealing in the pipes, usually the clear ones, and possibly the delivery valves of the IP? If there's diesel right there in the IP and therefore the injector lines and injectors it should go immediately without touching the throttle. Giving it a bit of thrutch as you are doing may be enough to overcome this. Any bubbles in evidence straight after firing up? Did they introduce some electrickery into these later OM606 diesels?

 

[3 phase]

Yes maybe that's a possibility, I had air problems with my clear lines and got some viton seals from ebay, (Silversaloon is the expert on these), that cured my intermittent rough idling and poor starting. I did them at the same time as I did my GPs last xmas.

 

[Paul64]

Hi Guys,

Thanks for the info - another project weekend coming up methinks......
I'll check for air in the lines and perhaps change the seals anyway - can't do any harm - and see how it goes.
The fault does occur even after a quite short stop - going in to pay for diesel for example - would that be long enough to let the fuel run back I wonder??

Paul

 

[bolide]

The car should start pretty much instantly when warm and shouldn't need throttle to start at any time

Idle speed is set by the idle speed stabiliser ECU and does it by adjusting the fuel rack. It uses a CPS to detect engine rotational speed

If the car doesn't like to start I would suspect lack of compression (valve seat recesssion in the back two cylinders) or air in the fuel system (flattened O rings in the fuel system pipework)

Nick Froome
www.************

 

[Paul64]

Thanks Nick, I've just ordered up a set of Viton rings from Ebay and will change them out to start with.
The engine seems pretty clean on the inlet manifolding - only one tube had a bit of soot in it when I replaced the harness and the car 'feels' like it's done the 200k Km rather than been around the clock a few times so perhaps it's just the rubbers. It did have a few tanks of veg-oil through it before I bought it but it's back on diesel now. Perhaps that's degraded the rubber over time? Hopefully, not valve problems.....

Idle speed is stable with an occasional hiccup when the ac cuts in but otherwise, car runs very well.

All being well, another W124 in top form next week!

Paul