You never know what you'll find in a WRD

[ctaylor738]

I'm doing a little work on the side to help support my habit.  One of the cars I am helping is a 230SL with mixture ('way rich) problems. The first problem I am going after is that there is a lot of suction through the WRD even with the engine completely warmed up.  I took the WRD apart and found a couple of interesting things.


1. There is an adjuster to vary the movement of the plunger.  

2. At least on this WRD, there is a little knob that looks like it can be used to move and hold the plunger down.

Talking to Hans at H&R, I learned that the plunger in a 230 WRD only moves 1.1 mm.

So I used the homemade adjust to get the air valve to close.  I turned the screw out a bit, put the thermostat on and put it under the instant hot.  After a couple of iterations, I was able to get it so that the valve just closed when hot water was run throuth the thermostat.

Back in the car, the suction when warm stopped, but warm-up was poor, so I will have to do another round of adjustment.  At least the idle can now be adjusted with the screw which is progress and the idle mixture is OK at 4.4%.  

But still getting 7-9% CO at 2000 RPM so the basic rich running condition is still there.

[66andBlue]

Chuck,
I am surprised about the info you received from Hans - only 1.1mm ?!  
We had a few discussions about the old style WRD before and I believe it should be more in the 3-4 mm range.
See: http://www.sl113.org/forums/index.php?topic=5460  reply #6 by 113gray
I remember that the WRD pin on my 230SL had a similar range.

This topic might be of interest too: http://www.sl113.org/forums/index.php?topic=9244.0

[ctaylor738]

Well, I talked to Hans again this morning and he confirmed that 1.1 mm is the spec for th R-11 WRD.  You of course need to measure it with the rod against the plunger because it will freely extend another 2-3 mm.

He also said that the screw and jam-nut arrangement is correct and then went through a lengthy explanation of the adustment procedure.  When I described my prayer-and-instant-hot technique I believe his comment was "interesting ..."

[Jordan]

Chuck, the screws (2) at the top of the WRD are exactly like mine.  You didn't happen to measure the length of the rod at the bottom did you?  I can't remove mine without damaging the whole device.  I shortened mine a bit when I was trying to unsieze it (by banging on it) so ended up removing the shims to compensate.  The air shuts off when hot but I am not sure I am getting enough travel from the rod to push on the rack and lean out the gas.  Which leads to my next question.

How are you measureing the CO.  Where did you measure it and what instrument did you use exactly?
Thanks
Marcus

[66andBlue]

....  You of course need to measure it with the rod against the plunger because it will freely extend another 2-3 mm. ...

Thanks Chuck, that explains it!

[ctaylor738]

When cold, the rod extended 7 mm from the bottom.  After the instant hot, it was slightly more than 8 mm.  I use a Gastester to measure CO.  It has a probe that you shove up the exhaust pipe. 

I removed the plunger by taking out the adjuster thingy on the side of the air unit.  You can see it clearly on the right in Picture 2112 along with small pin that secures it.  I heated the area around the pin just a little and it came out easily with pliers.  You pull the aduster out and the plunger and rod slide out.

To my astonishment, I did a cold start and drive off this morning and the car behaved very well.  The idle didn't come up as high as it should, but it idled and drove normally during warm-up.

[Jordan]

Thanks Chuck.  The adjuster thingy on the side is broken off on mine and rusted into place.  I would have to drill it out to remove it.  I'm not keen on that in case I damage the valve.  I have no replacement and don't know where one might get another.

So it sounds like the lower rod does not need to move much (1mm) in order for the gas to lean out, if I am reading you correctly.  Is Gastester the brand name?  I will have to see if they are available around here.  I just want to confirm that I am not running rich.

[ctaylor738]

Correct but you need to get the correct starting position with the shims and the adjuster.

It's a Gunson Gastester.  I bought mine on ebay a few years ago.

They changed the color of the case and the price went up, but seems much the same unit.

http://motors.shop.ebay.com/__?_from=R40&_trksid=p3841.m39.l1313&_nkw=gastester&_sacat=&rvr_id=235072810561&clk_rvr_id=235072810561&MT_ID=336&crlp=7213897731_9887&tt_encode=raw&geo_id=491&keyword=gastester&adgroup_id=521541651