testing early fuel injection pump thermostat

[mnahon]

It seems that the (tall) thermostat on the early 230SL fuel injection pump can be tested by placing in boiling water to see if the pin extends. Does anyone know how much it should extend?

[Benz Dr.]

It only moves about 1.2 mm on a 230SL but you have a 280SL so it uses a different thermostat. The one on a 280 moves a lot more - maybe 7 -8 mm.

[Pawel66]

The new thermostat (new style) I bought from MB two months ago extended exactly 7mm. The old one I had only 5mm.

[mnahon]

Thanks Dan, Pawel,

I've added this information to the Technical Manual on the WRD page:
https://www.sl113.org/wiki/Engine/WarmRunningDevice

I added the following text:
The central pin of the "heat feeler", or thermostat, extends to adjust the mixture as the coolant temperature increases. The thermostat can be tested by placing it in hot water and measuring the pin's extension. The thermostat of the early 230SL looks very different from the one in later Pagodas (picture below shows the later thermostat); and it is much more expensive if you can even find it. The pin on the early thermostat should extend about 2 mm when tested in hot water, while the one on the later thermostat extends by about 7 mm.