WRD versions

[miked_md]

I had posted earlier about the 67 230SL that I am restoring and the challenges I have had getting the WRD to provide enough air for the extra fuel during warmup.  The car runs great once warmed up but not enough air as it warms up. 

When I bought the car it hadn’t run in five years and it had a broken automatic transmission.  The car came with some spare parts including a disassembled WRD with a stuck air valve.  I have rebuilt the transmission and performed other repairs and the car runs and drives well except for warm up.

The WRD installed currently has the black adjuster screw.  The disassembled WRD that came with the car does not, and matches the one shown in the technical manual and in my BBB for 280sl’s.  I am beginning to suspect that the disassembled unit is the one that came with the car originally and my problems are due to an earlier version of the WRD being fitted.

Reviewing the forum there seems to be some confusion about which WRD a 230SL should have.  My injection pump is an R11 pump.  My car was produced in December 1966 so it is a late 230SL.  Photos that I have seen of other late 230sl’s injection pumps look more like the dissembled unit that came with my car.  The dissembled unit has the 3 inches of metal air line (consistent with photos of other WRD of that VIN range).  The unit on the car has a short nipple to attach the air hose instead.

I have successfully freed the stuck air valve on the dissembled unit and may try swapping it with the unit currently installed.  I would be interested in hearing from anyone that knows when they stopped using the adjuster screw and switched to the newer unit without.  I suspect it was done middle to late in the 230sl production run. 

Thanks,

Mike

[BobH]

Hello, i know very little about these pumps, other than what i've read, but i would have thought that all 230's would have been fitted with the r11 pump with the same WRD.  The 250SL then had the r18, with the later WRD.  I can't imagine why any original r11 pumps had later WRD's fitted unless they'd been replaced due to a lack of the early spare parts

Have a look on here and maybe speak to Blackforest for some advice, he's also a member on this forum

https://www.blackforestllc.com/boschr11

[rwmastel]

Mike,

Hi.  I assume you read this?
https://www.sl113.org/wiki/Engine/WarmRunningDevice

If you can get the plunger working on the original thermostat, that would be great.  They are NLA.  Member slschock just sold a couple on our site.

Can you post pictures of both WRDs?  I have a r11 pump on my Oct 1966 230SL.  I'm curious to see what this other one looks like.

Can

[BobH]

https://www.sl113.org/forums/index.php?topic=36149.msg264201#msg264201

[miked_md]

Here are two photos.  The technical manual indicates "The (WRD) on the earlier W113 engines (230SL) is different from those on the later 230SL, 250SL and 280SL, but the function is the same."  Many postings in the forum don't seem to make the distinction between the versions used for the 230SL.  I would be curious if your WRD looks like this. 

Thanks,

Mike

[miked_md]

I replaced the WRD that was installed with the one that I repaired that came disassembled with the car.  When I first tested it the car was hard to start and wasn't running right.  I gave the idle mixture screw a total of 10 clicks clockwise and that resulted in a consistent idle.  The split linkage test showed a small RPM increase with extra air so probably about right. 

What was telling is that during warm up the split linkage test adding air did not cause a big increase in RPM, previously it would rev to 1600 RPM.  The old WRD seemed to function properly allowing air flow and shutting it off once the engine got to temperature but it was way too rich even after removing two oval shims.

Here are photos of the removed WRD.  This unit has the black adjuster screw.  The newly installed WRD looks like the one in the tech manual which does not have the adjuster screw.