230SL Injector Pump Thermostat Elongation

[mistertj]

Does anyone know how far the Injector pump thermostat center plunger should travel if working properly?

[mrfatboy]

I can't remember if the 230 and 280 thermostats are the same or not. But I remember it's about 23mm for the 280 version.

You can also check out this thread or do own search.

https://www.sl113.org/forums/index.php?topic=20128.0

[mistertj]

Mine looks like from cold to boiling water, the plunger extends an extra 3 to 4 mm. Don't know if that's normal?

[Benz Dr.]

It needs to move at least 1.1 mm or about  .050''  Make sure it's dead before buying a new one because they're about 1K  now!

[mistertj]

Guess mine is ok then with the 3 to 4 mm movement. Does seem kind of a small amount of movement given that it has to move the choke barrel enough to block air flow.

[Pawel66]

mistertj, please make sure you are looking for a good part if you are looking for it. 230 might have had a different one than the later cars. Check the Tech Manual, there is a chapter on it.

But first of all: have you been listening to the air flow at the pump air filter? I suppose your pump has one, as the later ones. You actually hear the air hisss when the car is cold, then this hisssss dies away after a couple of minutes. If this is what is happening, maybe the WRD works ok.

Have you checked the barometric compensator? This is quite a commmon fault and it makes the mixture lean.