Author Topic: Idle speed adjusting screw does not click  (Read 786 times)

Aart

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  • Hi there! I'm the proud owner of a 250SL 1967
Idle speed adjusting screw does not click
« on: May 15, 2024, 11:23:29 »
The idle adjustment screw on my injection pump could not be turned anymore after I had turned it a few clicks CW. I removed the cold start solenoid and a few hoses, and then the big nut with the knobbed spring loaded fuel adjustment device. The picture shows what I saw: the central screw, the leaf springs, and the two black and the two white screws.

I can now turn the central screw, the idle adjustment screw. But I do not hear it click and also do not feel much pressure of the springs on the notches of the central screw. It feels kind of loose. My question is, can I take the leaf springs out with the pump still in the car, and bent them in such a way that they regain their tension and press more firmly against the sides of the central screw again? Or should the leaf springs be replaced?

The platform that holds the 5 screws and the springs can be moved a bit. It is not firmly attached to something.  Is that normal?

And the central screw, is it screwed into something behind the platform? Is it possible that something is broken there?

Your replies are much appreciated!

Aart

ctaylor738

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Re: Idle speed adjusting screw does not click
« Reply #1 on: May 16, 2024, 01:12:48 »
The spring is actually one piece in a V or U shape.  It has two little tabs on the open end to hold it. 

I can't see clearly, but it looks like your spring may be broken.  I think it would be a real challenge to replace it with the pump in the car.

Attaching a picture of how the spring should look fitted among the adjusting screws.

Cheers,

CT

Chuck Taylor
1963 230SL #00133
1970 280SL #13027 (restored and sold)
1966 230SL #15274 (sold)
1970 280SL #14076 (sold)
Falls Church VA

Aart

  • Full Member
  • Junior Level
  • Netherlands, Gelderland, Arnhem
  • Posts: 8
  • Hi there! I'm the proud owner of a 250SL 1967
Re: Idle speed adjusting screw does not click
« Reply #2 on: May 18, 2024, 15:21:49 »
Do you remember whether you could move the platform with screws somewhat? Or must it be a firm fix on some other part behind it or around it? If that is the case, then something must be broken in my IP.

Btw, as far as I can tell, the spring is not broken.
Aart

ctaylor738

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Re: Idle speed adjusting screw does not click
« Reply #3 on: June 10, 2024, 15:19:24 »
Sorry, I missed this.

Yes, I recall that you can move the assembly.  Did you find your problem?

CT
Chuck Taylor
1963 230SL #00133
1970 280SL #13027 (restored and sold)
1966 230SL #15274 (sold)
1970 280SL #14076 (sold)
Falls Church VA