Need a WRD - anybody know where one is?

[ptooner]

I have a long standing cold start problem.  THe engine starts then dies in a second or two. (Apparently on the squirt of gas from the CSV)  Then after several more attempts it will start and run rough for a while until it warms up.  I had the WRD (the thermostatic thing on the end of the injection pump) rebuilt a couple of years ago and it worked perfectly for a couple of weeks.  THen it went back to  it's usual situation so I'm pretty confident that the problem is actually with this device.  I have no idea where to find another one.  Any suggestions?   It's a 65 230SL
 
Thanks
Gerry

[w113dude]

Why don't you fix your own? There isn't much in there! check your thermostat that's inside WRD make sure it works then take it from there.

[ptooner]

I paid Brumos Mercedes around $1000 to rebuild it two years ago.  If they couldn't make it work but two weeks it seems unlikely that I can do better.
Gerry

[ctaylor738]

Pretty hard to not do better than that!

Can you unscrew the little air filter and see if the WRD sucks air when the engine is cold, dimishing as it warms up?

Is the thottle plate fully closed at the idle position so you're not getting extra air?

Is the cold start valve actually spraying when you do a cold start?

[ptooner]

Pretty hard to not do better than that!

Can you unscrew the little air filter and see if the WRD sucks air when the engine is cold, dimishing as it warms up?

Yes, it doesn't suck air.

Is the thottle plate fully closed at the idle position so you're not getting extra air?

Yes

Is the cold start valve actually spraying when you do a cold start?

Yes

Just tried taking the little air filter off and filling the area in there with wd40.  After starting and stopping the engine a couple of times I think I felt a LITTLE vaccuum at the hole where the filter goes.  Maybe.

Gerry

[ctaylor738]

Well, if no suction when cold, then one or more of the following has happened:

- the wax-filled thermostat element has gone bad (unlikely and expensive)
- the slide valve has frozen in the tube
- the slide valve has gotten out of adjustment

The attached picture tells the story.  You can see the thermostat on the right, and the slide valve in the middle with its adjustment.

You need to take the WRD off and disassemble it as shown.  To check the thermostat, hold it with the little rod up and measure how far it sticks out when cold, then run some 180 degree water through it (or dunk it), and re-measure the distance.  It should be about 1 mm greater.  If it doesn't move, then you need a new element.

Make sure that the slide moves easily in the tube.  A little WD40 or some PB-Blaster may help.

Then re-assemble and test that the slide is just at the top of the air passage at about 50 degrees (winter in Jax).  Then use the hot water to heat the tube to 180.  The slide should move down to close the air passage.  Use the screw to adjust as required.  Because of the limited travel, the priority is to make sure that the air passage is fully closed at about 180 degrees.

[ptooner]

OMG, you're saying this thing moves one silly millimeter?  No wonder it's so hard to get it right.  I certainly appreciate the photo and I have already printed it out.  If I understand correctly you are saying to adjust the screw in the brass cylinder end?  I have seen instructions somewhere to change the number of bushings somewhere for adjustment but I'm not sure where.  I suspect that it isn't going to the cold setting so it's quite likely that the thing is stuck.  It does seem to be working a little better after I sprayed a lot of WD40 into it through the opening where the air pipe goes.  If I understand correctly, screwing the screw into the cylinder would tend to make it stay richer and screwing it out would make it leaner.  Both conditions only when cold.  Do I have that right?

Thanks
Gerry

[ctaylor738]

If the slide is stuck and it sounds like it is, PB Blaster is a lot more effective than WD40.  The thermostat is pushing the slide down as the engine warms up and the lever in the pump pushes it up when it cools off, so you might get lucky with a few days of spray and drive.

You have it basically right.  The screw changes the starting and ending positions of the slide.  Like I tried to explain, you want to adjust it so that the air passage is just barely closed when the engine is at operating temperature.

[glenn]

Neuter the WRD....   You're in Jacksonville---You only drive it between 60 and 90 degrees.   Take the WRD off.  Replace it with a plate with an adjustment screw to press down on the lever inside the FI pump.  Adjust to where it starts and leave it.

Search the Form for pictures. ..  Cost you about $8.50.

[w113dude]

Neuter the WRD..... Good idea for FL

[ptooner]

Neuter the WRD....   You're in Jacksonville---You only drive it between 60 and 90 degrees.   Take the WRD off.  Replace it with a plate with an adjustment screw to press down on the lever inside the FI pump.  Adjust to where it starts and leave it.

Search the Form for pictures. ..  Cost you about $8.50.

I understand the concept but I don't see how that is any different than operating it stuck like it is now.  Starts and runs perfectly when its warm but is very hard to start and keep running with it cold.  If I replace it as you suggest and adjust it so it will start cold won't that make it run rich when it warms up?

Gerry

[w113dude]

This WRD is separate from your cold staring valve CSV (on the right side of your manifold) the screw that Glenn is talking about on the cover plate that caps WRD will keep it at the right level of fuel consumption at all time and wont be running rich on the other hand if WRD is stuck open or close it will affect your start or after depending on where it's stuck.
you are just bypassing the device.

[ptooner]

If the slide is stuck and it sounds like it is, PB Blaster is a lot more effective than WD40.  The thermostat is pushing the slide down as the engine warms up and the lever in the pump pushes it up when it cools off, so you might get lucky with a few days of spray and drive.

You have it basically right.  The screw changes the starting and ending positions of the slide.  Like I tried to explain, you want to adjust it so that the air passage is just barely closed when the engine is at operating temperature.

Okay, based on everyone's advice I tore into it today.  Like so many things, the repair was much easier than the anticipation.   Once I had it off it was extremely obvious that the slide was stuck.   I gunked it up good with breakfree and applied hammer persuasion to each end.  There is no way to get the slide out because there is some sort of a grub screw arrangement that is held in place by a roll pin.  If I could get the roll pin out I can't see how to remove the screw thing - it appears to have no head or perhaps it's just rusted.  Anyway, after a very short amount of persuasion the slide began to move freely.  I added a bit of white lithium grease for luck and reinstalled it.  The engine started instantly and idled like it always should have and never did.   

Really makes me wish I had tackled this thing years ago. 

Gerry

[bogeyman]

What about your $1,000 "rebuild"?

[ptooner]

What about your $1,000 "rebuild"?

Yep, I'm wondering that also.

Gerry

[Benz Dr.]

But you didn't actually fix it unless you fixed ity properly. Want to know it quit working after a few weeks two years ago?
The small housing where the thermostat sits needs to be sealed properly or coolant will leak down into the slide valve housing making everything sticky once it dries. It will usually stick in either the full down or full cold position. You freed it up which is good but if you didn't seal it up it may sieze up again. I use copper silicone - not too much either; just enough to make a good seal.

  I don't much care for advice that offers a jury rig repair as a viable option. Sometimes you're left with little choice but I don't think this was one of those times. 

[glenn]

Re: WRD fuel management design...   Idle air on a at-temp engine enters thru a 3/8" hose throttled down by the idle air screw 90%, or so, closure on the air flow line.  Idle fuel is at a minimum from the FI pump.
    On a cold engine, the 3/8" air valve is wide open in the WRD and the FI pump WRD lever is at max additional fuel.    i.e., There is 10 times(+ or minus) as much air and fuel entering thru the WRD.  As the engine warms, the additional air and fuel is gradually reduced to zero, back to the warm engine idle conditions.
      Also, on 'Start' the engine gets FI pump bump to full on the rack and a CSV squirt.  There is no additional air on 'Start'.  

     This is fuel management, control of the fuel air ratio.  You tell me???

[Benz Dr.]

Uh...... yeah. That's basically how it works.

[glenn]

Yeah, that's 'how it works'.   But, 'how IT works' doesn't work in the real world.  The fuel/air ratio on the warming engine is???

[Benz Dr.]

Where are you going with this?

[66andBlue]

Where are you going with this?

to -> PPP or "Perpetual Pagoda Palaver".   

[ptooner]

But you didn't actually fix it unless you fixed ity properly. Want to know it quit working after a few weeks two years ago?
The small housing where the thermostat sits needs to be sealed properly or coolant will leak down into the slide valve housing making everything sticky once it dries. It will usually stick in either the full down or full cold position. You freed it up which is good but if you didn't seal it up it may sieze up again. I use copper silicone - not too much either; just enough to make a good seal.

  I don't much care for advice that offers a jury rig repair as a viable option. Sometimes you're left with little choice but I don't think this was one of those times. 

That sounds like a good idea.  The engine now starts better than it has in the 20 odd years I've been driving it. Anyway, I'm not clear on where you are telling me to seal.  Can you expound a bit?  I know there is an o-ring between the water part of the assembly and the air portion.

Gerry

[Jordan]

I believe Dan is referring to the seal between the thermostat and the housing in which it sits.  You don't want coolant leaking from the thermostat housing into the valve assembly below it so you need to seal this area.

[Benz Dr.]

There is a copper seal between the thermostat and the housing but thetre's nothing below that. If even a few drop of coolant leaks into the slide valve it could make it stick. What you're doing here is preventing that from happening or at least trying to prevent it from happening.
 I use brake grease in the slide valve - it can take a lot of heat. Leaving it dry can also make it stick.

[db180]

I'm new to the site and also the w113, I recently acquired a 1967 250sl which has difficulty starting - it does eventually start.

I started with the CSV, which was clogged, and corrected that first - this made it start a little easier.

I've now started on the WRD and after reading several posts it looks like there are 2 versions, an early and late. This post seems to talk about the early version where the thermostat is meant to move very little around 1-2mm whilst the later one moves 6mm+.

So I removed my late thermostat and dipped it in the correct temp water and it moved 2mm max - can I assume that it is buggered or is this normal for the late type?

Earlier in this post someone mention that they rarely fail, is this for the early model only - or both ?

Help and advice greatly appreciated.