Another Stuck WRD

[Travis71280]

Hey Everybody, I was wondering what is the best way to disassemble a stuck WRD without damaging it. The car has sat for 15 years and I was only able to get the heat feeler removed, but the pin and air valve assembly is still stuck in the housing. I just don't want to break anything. I tried taping on the pin on the bottom, but it seams like there's a spring behind it. Thanks again in advanced. (by the way its the later style warm running device).

[Benz Dr.]

The same thing I told Jordan. ( Marcus )  A little bit of heat, then let it cool. Do that several times until it starts to move a little bit. Once it starts to move hit it with some penatrant before it cools off. It should eventually come loose and move freely up and down.
 
Once you have it freed up use a bit of grease on the sliding portion and screw it back down on to the IP. There should be a small ring between the slide valve ( top ) and below the thermostat housing. Use some sort of sealer between these two parts or anti freeze will leak into the slide valve housing and it might seize up all over again. Coolant made it stick so you have to keep it out of there.

[Tomnistuff]

I know this thread is dormant since March, but the subject is appropriate to a question that I have; and asking it poses no risk of hijacking the thread.

I'm new here and perhaps do not use the proper terminology, but is the WRD the same as what BudsBenz Catalog calls the injection pump thermostat, that sits on top of the rear of the injection pump and responds to coolant temperature?  If yes, what are the symptoms of a stuck WRD?

Three years ago, on a cold evening, I started my 67 230 SL cold at a restaurant.  It ran well at start.  On the way home, it ran worse and worse as it warmed up, emitting black smoke (rich) and misfired terribly.  Barely making it home, I parked it and went back to work on the restoration of another vintage car.  I've just sold that other car and now need to repair the pagoda.  I suspect a stuck WRD, if that's what I think it is.

Can one of you briefly describe the symptoms of a stuck WRD?

Pardon me!  Please ignore the question and the post.  I should have looked at the Technical Manual first.  I think that a stuck WRD is my problem.

Thanks,

Tom Kizer

[ja17]

Hello Tom,

Yes, your diagnosis could be correct.   It sounds like the WRD got stuck in the cold (rich) position during that cold start and never leaned out.  So you engine just began running richer and richer as it warmed up. 

Get a fresh set of spark plugs, and remove the WRD and clean it. Make sure that it is working.  Change your coolant while your at it. It is probably very acidic by now.

[Tomnistuff]

Thanks for your judgement, Joe,

I've been in the garage for most of the evening and have new information.  Right part and right effect but wrong cause.

When I got it apart, the WRD was free to move, however, the WRD housing was filled with rust and scale, causing an almost complete blockage of coolant flow around the thermostatic element.

The WRD responds to hot water from the tap, but it wasn't seeing very much hot water, if any, from the engine.  That saves me about $900.00.  The 230 SL part is about 15 times more expensive than the 250 and 280 parts.  With hot water from the tap flowing by gravity into one of the tube openings, there was only slight weepage flowing out of the other.  The guide rod in the control valve housing is very free-moving, so at least that's good news too.

The housing for the WRD is almost corroded away from the inside.  My metal coolant tubes are also pretty rusty and scaly inside, so I've got a lot of tube cleaning and subsequent leak checking to do.  I know that cleaning the rust and scale can create leaks.  I've also found the wonderful but really complicated backflush procedure in the Technical Manual.  I'll take my time and do that too, along with cleaning the fuel tank, fuel pump, and lines, very carefully.  If the cooling system is that bad, I imagine the fuel system is too.

Maybe I got lucky this time.

Tom

[ja17]

Yes, that's what happens when the coolant is not changed on a regular basis.  Glad you did not have to buy a lot of expensive parts!

[Travis71280]

Thanks Benz Dr, finally got around to it today and finally got the slide unstuck and moving freely. Unfortunately, I accidentally tapped the guide rod out of the spring keeper. I soldered it back on, but when I reassembled the warm running device, the guide rod is even with the opening. How far out should the rod stick out from the housing during room temperature or will this work already?