Can the early (long) WRD thermostat be rebuilt? Other options vs. buying new?

[Greg R.]

After a few month hiatus I'm paying attention to the little car.  My WRD air valve moves freely and the air filter flows well but the flow didn't change when it reached operating temp (80C).  Uh oh.

I confirmed that the long thermostat's plunger doesn't extend by boiling it for a few minutes.  Crud.
 +/- $750 for a new one is a hard pill to swallow.  What are my other options short of eliminating the WRD completely?  Can these thermostats be refurbished?

-Greg
1967 230SL (250 motor), sat for 10+ years...

[Benz Dr.]

Better bite the bullet while you can still get one.

[Cees Klumper]

Can't the thermostat housing be modified, e.g. replaced by a later, shorter one so the later thermostat fits?

[Tyler S]

Greg, Your signature line says you have a 250 motor? It should have an R18 pump with the newer style WRD thermostat.

[Greg R.]

Good morning, Tyler.

Yes, the motor is a 2.5L but the pump and accessories seem to be original to the car.  (I've corrected my signature.)  I'm new to both Mercedes and mechanical fuel injection so as not to fool myself I just checked: Bosch PES 6KL 70/120 R11.

The thermostat is definitely the long one.  Looks like I may have to bite that bullet.  Coincidence that the WRD thermostat looks like a 20mm shell casing?  :-]  I'll wait a little while to see if anyone else chimes in or has a known good used one for sale. 

Headed to the WTB forum,

Greg

[Benz Dr.]

Isn't the R11 pump used on a 230SL. If that's the case then you have the wrong pump on your engine.

[Greg R.]

You're 100% correct, of course.  My understanding from the PO is it worked well enough for a couple decades until it was parked around 2010.  How well it actually ran I don't know.  I wonder if the slightly more fuel the 250 needs could be crudely added by adjusting the barometric compensator's shims.

Maybe not.  Regardless, the first step is to get it to start and idle well when both hot and cold.

-Greg