230SL WRD air valve sleeve disassembly - how?

[Tomnistuff]

How does one disassemble the WRD shaft/pin/valve in the upper left of this photo, and are there possibly shims inside?  It's from a 230SL with the long very expensive or unavailable thermostat.
Tom Kizer

[wwheeler]

I could be wrong, but I think that nut and screw on the piston are your adjustments on the early WRD. No round shims. I believe that was ditched for the shims. In reality, this only would need adjustment once or twice in a lifetime when set correctly from the factory. The adjustment will simply increase or decrease the temperature that the WRD shuts off.

[Tomnistuff]

Hello, Wallace.  I apologize for taking so much time to respond after you answered my post so quickly.  Since I have been working on and analyzing the WRD on my 230SL, I seem to spend a lot of time confused. I'm worse than a presidential candidate.  I make up my mind about something, then I flip-flop-flip-flop, accomplishing nothing.

Here is my attempt to explain why I am convinced that I "need" a place to add or subtract shims between the WRD air valve sleeve and the tip of the rod/pin that actuates the fuel lever inside the pump.  It also explains why I think there must be a way to add and remove shims.

My WRD was malfunctioning terribly during warmup because:

1). the hex head dowel with the small pin on the end that limits the upper travel of the air valve sleeve (upper piece in the photo) was improperly installed and adjusted.  Its "stop-pin" prevented the sleeve from moving to the top of the bore during thermostat cool down and therefore severely reduced the air flow to the intake manifold during perhaps the first half of warmup,  (diagnosed by blowing through the fitting with the sleeve at the upper limit of travel).

2). the small black hex head machine screw in the top center of the air valve sleeve was protruding much too far from the top of the sleeve, causing it to be contacted by the thermostat pin during installation, even in its cold/retracted position, causing the sleeve to mostly cover the air hole in the body.  That yielded a severe reduction of the intended air flow during warmup and finally resulted in a complete air shutoff at 50 degrees C, instead of 80 degrees C, (diagnosed by correlating air shut off with the car temperature gauge).

3). by resetting the position of the hex head dowel to put the sleeve "stop pin" at its upper position in the bore , and by screwing the small black hex head machine screw as far as it would go into the air valve sleeve to reduce initial installation contact with the cold/retracted thermostat pin, the results of a cold start and warm up were that the initial stable cold idle speed was about 1,300 rpm and the WRD air flow didn't shut off until a temperature of 80 degrees C, with an idle speed of 900 rpm.  Luck was on my side with the first change I made.

The only problem was that a split linkage test during warm up said it was rich the whole time.

Conclusion:  If the parts above the air valve hole are installed, adjusted and functioning correctly as the above results say they are, but the mixture is too rich during warm up, then to my mind, I need to increase the engagement of the shaft to the fuel lever inside the pump without moving the air valve sleeve relative to the air valve port in the housing.  In other words, I need to lean out the mixture without changing the air flow characteristics and air shutoff temperature.

I think maybe removing an oval shim will increase the shaft tip to fuel lever engagement and lean it out a little, but I only have one oval shim installed, and it's really thin.  I will try that but if it doesn't work, is there another way to accomplish the lean out without having to start over with the entire IP calibration at all temperatures?

All of the above is why I think there must be shims I can add somewhere between the lower shaft and the air valve sleeve to increase the shaft to fuel lever engagement and lean it out.
 
Any ideas? Comments regarding my logic?

Tom Kizer

[wwheeler]

The dowel pin with the offset pin’s function is to disable the WRD entirely. No adjustment and is like a switch, either off or on.  The reasoning is that if the WRD is stuck in the cold position, you can use this to make it permanently in the “hot” running position. Therefore make it so that the car is drivable when the engine is warm. This is the same on my 220SE. It was not a feature on later pumps with the shorter thermostat.

As the WRD piston moves down and closes off the air flow, it also reduces the fuel in the pump. That relationship cannot be changed. So when the air shut off at 50*C, so was the fuel. By shortening the nut/ screw on the piston, you are changing the temperature when the air valve and fuel shuts off from 50 to 80*C. That would be the same on the later pumps as reducing the round shim height. The thing you want to make sure of is that the air flow does stop at warm engine temp.

Keep in mind that these engines do run pretty rich when cold. What has been told to me was that it is the rare engine that runs perfectly well both cold and hot. I am satisfied that my engine runs OK cold and much better hot.

 

[Tomnistuff]

Thanks Wallace.  Your last sentence made me realize that I should adopt your philosophy.  Mine, since a couple of days, starts and runs OK cold and much better hot as well, so I should be content.

I will stop worrying about it and just be happy.

Thanks for making my day.

Tom Kizer

[Tomnistuff]

By the way, Wallace, I have read elsewhere what you said in your first sentence, but I can't remember where.  However, if the dowel pin is turned to a position other than on or off (two discrete notches machined into the rolled pin engagement land of the dowel), it will stay there in the unintended position.  In my case, the rolled pin was not inserted deep enough to engage the bottom of one of the two machined notches.  The fuel lever return force acting on the bottom of the WRD shaft is apparently not strong enough to turn the dowel back to one of the intended positions by acting on the offset pin on the end of the dowel.

Anyway, knowledge is power.

Thanks again.

Tom Kizer

[Tomnistuff]

Hi Wallace.  I have decided to remove the one last oval shim to compensate for the wear on the WRD shaft tip shown in the two attached photos.  It's not much but to me it looks normal for unknown mileage in 54 years.

Wish me luck

Tom Kizer

[wwheeler]

I read about the offset pin in the service manual for a 220SE. Yes, that is a two plunger pump where as the 230SL engine is a six plunger. I am away for a few days and do not have access to the sheet, but can attach it later if need be.

But the thermostat and this pin are the same. When rotated, the offset pin is supposed to push down on the piston assembly to where it is in the full hot mode. When rotated back in the normal position, it allows the thermostat to act upon the assembly. I have not messed with this assembly yet, but will in a few months.

Good luck!