Im having an issue with a 616 motor where the throttle will not return to an idle position, but instead sticks midpoint. In playing with it, the two springs near the rear of the injection pump are super rusted and need to be replaced.
Also its doing this with all linkage disconnected, so there is nothing binding of that nature causing it. My question is are these external springs the only items that return the throttle assembly to idle? is there anything internal to the injection pump?

second question is will any spring do that has sufficient force to pull the rack back? IE, can I get one from a hardware store or does it have to be an MB specific part? The throttle seems to move easily back and forth, it just won't return all the way which im attributing to the weak springs

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This post brought to you by Carl's Jr.

The governor mechanism is essentially a set of weights that spin - see chapter 07-010 and you can see what will happen if they get stuck.

My play IP was full of some pretty nasty gunky junk...

As for your springs post up the wire diameter; the mean coil diameter; the length and the number of coils and I'll calculate the stiffness for you. You can then check this specification against suitable replacements. (I'll explain how to measure it if you're not sure)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

there is a spring under the pump at the back with a bracket attached to the block, see if its there if there may not be attached correctly.

those are the ones Im referring to, sounds like they alone control return to idle.

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This post brought to you by Carl's Jr.

It could be that the injection pump is sticky like yours was, engine hasnt been started in about 3 years. Thanks for the page, I need to check it out. Im assuming from what you say that you have a set of weights that spin, and these external springs draw them back, but nothing internal could be an issue apart from the injection pump being gelled up with old fuel and whatnot.

here are the springs, Im wondering why there are two instead of one stronger spring? -



here they are removed, forgot two measurements for you, larger spring is 24mm long, and smaller spring is 39mm long

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This post brought to you by Carl's Jr.

Right - here are my results.

Do they sound about right - believable?

(I've been calculating values for much stiffer springs recently so these numbers seem really weedy to me!)

For the smaller diameter spring I reckon there's a stiffness of 0.32 N/mm

For the larger diameter spring 0.18 N/mm

So that means the smaller diameter spring should be about twice as stiff as the larger one - is that the case in real life? (i.e harder to pull the small diameter one than the larger diameter one)

To test the springs =>

Get something that weighs about 100g

Hang this weight on the end of the spring

The small diameter spring should extend by about 3mm and the large one about 5.5mm

(calculation => Applied load (N) / stiffness (N/mm) = deflection (mm) => to convert grams (g) into Newtons (N) divide by 1000 and multiply by 9.81)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

TENSION SPRINGS!

Sorry I forgot to mention that to get the measurements in the right ball park for the test above you need to start off with a small weight in your case say about 30 - 50 g to pull the tension spring apart. I can calculate the initial tension required to do this if you need it but in practice so long as the initial tension has gone then the spring behaves as described above until it gets so long that the external diameter of the spring starts to neck / gets smaller and the limits of the material go beyond the elastic limits...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Doubling up is stronger and provides safety if one breaks on you.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Where is the 2nd spring in the pic???

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
No longer selling Cluster Needles Paint
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Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more

The smaller diameter one is inside the larger, covered in a plastic sheath

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This post brought to you by Carl's Jr.

Thanks for the info stretch!

I'm going to revisit this when I can actually fire the engine, my feeling is that the injection pump might be gummed up a little and sticks where it sat for so long. I'm considering removing it and cleaning it out with solvent. I'm going to try a controlled test fire first though

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This post brought to you by Carl's Jr.

Sounds like a good plan

If you get to taking covers off of IP governors then there are some pictures showing what you might find here =>

Papa's got a brand new om617 IP to play with!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

There is a spring for the accelerator pedal lever and one on the IP. Both return the IP to idle.

oh man! thats whats missing!
Thanks for pointing this out, this engine is in a non stock application and ill be adapting it to a cable pedal, and i just ran out and checked low on the firewall on my 240, and you are indeed correct, its a big spring too, which would probably take care of the sluggishness Ive been seeing.

I have to duplicate it

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This post brought to you by Carl's Jr.

(Laughing)

Well if you measure the distance along the angle on the dangle => estimate the mechanical advantage <= you'll be able to recalculate it for any new set up you can think of. {If you want me to calculate the stiffness of that other spring let me know}

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!