Gents,
I decided to test my early style WRD thermostat. This is on a two plunger W111 fuel injection pump but I believe the six plunger pump on the 230SL used an identical thermostat
The pin length is 6mm at room temperature which is the correct value.
According to my manual the pin should extend a further 0.5mm for every 10 Deg C increase in temperature. This would equate to 10mm at 100 degC.
I am only getting a 2mm increase using boiling water (8mm). I put it in the oven at 120 degC and got 9mm. Does anybody know any tricks to "loosen" it up a bit....I believe they are about a thousand bucks for a new one !!
Also there is lots of posts suggesting immersing the thermostats in boiling water. I did this initially and could see some air bubbles escaping from around the pin as water ingressed into the housing. If you are not supposed to immerse the whole thing then it might be worth making this clear in the technical manual (for idiots like me). The pin wouldn't be in contact with water whilst fitted to the car.
Regards
Peter
