Idle fuel/air adjustment

[Pawel66]

It is easy to check if air is shut off - just remove the filter and plug the hole - see if the car still stalls or not. Also: when you remove the air filter, you feel very well with your thumb if there is suction.

WRD getting hot - the thermostat housing becomes bloody hot very soon as the engine warms up.

But again - on stalling when warmed up - I had it when idle was far too rich or far too lean, right around 80 degrees. I managed to check which way to adjust it by split linkage test and took it from there.

[col320ce]

When idling (not driving) I can't get the air to shut off on the wrd so I think this is my problem. It does get hot but a fair bit of air still flows. It seemed to work on the bench test so u assume I need to drive the car to get it fully warm (and off). So unless you think there is something faulty with the wrd I think I'll leave everything until I can drive the car to warm it up.
BTW the air filter has a lot of resistance in it (big difference in air flow with it on and off)... So I'll get one of these too

[ja17]

Sometimes the metal coolant pipes to the WRD get plugged making the WRD stay cool and engine run rich.

[col320ce]

Thanks Joe... I'll pull them now and give them a clean.

[col320ce]

Well there was definitely a partial blockage on the top water pipe. It gets much warmer now but still not enough to turn the air off (but gets closer).  I don't really understand this but I have ordered a new thermostat and FIP air filter. 

I have just realised I have a PES 6 KL 70 B 120 R18 pump on my car which I think is from a 250 or later.  If the pump has been swapped it's possible that it was never set up properly.

[jeffc280sl]

here are some pics of the device.  let us know if you have any questions.  the air valve maybe stuck.  water feed and return must be clear

[Benz Dr.]

You have the wrong pump on your engine and it may never work right. You can try turning the BC to adjust to a leaner mixture but you're already paddling up stream.

[mrfatboy]

After the car stalls during warm up what do the plugs look like?

Toward the end of the warm up cycle the WRD plunger hits its stop first inside the pump.  The air slide is the last thing to fully close.  This causes a lean condition right before the air slide is fully closed.  If your WRD is not fully heating up to close that last little bit of air off you will be in a perpetual lean condition. You mentioned before that you start hearing pops in the muffler which JA17 suggested  fuel starvation (lean). Sometimes its hard or takes a long time to get that last little be of air slide fully closed just by idling.

Did you find your round shim that you lost?  The round shims control at what temperature the slide valve starts to move.

When I have taken off my WRD there is plenty of coolant that pours out unless I plug the lines.  You mention you don't have that much.  Do you have the correct amount of coolant in your system?  Possible air pockets?

One last thought,  it's remote but you never know.  Make sure the WRD is properly assembled.  Pay attention to the round shims. If put in the wrong location the air slide can close then keep going a little bit and reopen on the other side.  You never know who was in your pump before you

[col320ce]

Dan ... If this was your car would you be getting the correct pump? Is that your advice for me?

I found the shim last night but it was not installed when bench testing and testing in the car (used a magnet to find it .
In hot water it bench tested ok, so I assume I'm just not getting there without actually driving the car...
However, I found someone on a Jag forum with a similar (same?) thermostat and said that the new ones moved further and faster than his old one. Even though mine closed the air valve the plunger did not protrude as far as suggested in the technical manual.
So I have ordered  new thermostat to rule that out.  The hardest part I think will be getting it out of the housing ... any suggestions?
If that fails I'll wait until I have a spotter that can help me get it out of the carport so I can drive it to get warm...
If that all fails I'll look for the correct pump and get it reconditioned before putting it in.
One last thing, I haven't investigated the fuel pressure component; do I just attach this on the fuel line from the pump to the FIP?

[mrfatboy]

I'm not sure if this will help at this point but you can take off the air filter and place a mirror and watch the air slide close as the car warms up. At least you can confirm how much it actually closed.

Or course,  as everyone has said before there should be no suction when the car is hot. 

Another thought. Could the air slide be actually closed but just worn and letting air through?  Using the mirror could confirm.

[Pawel66]

So I have ordered  new thermostat to rule that out.  The hardest part I think will be getting it out of the housing ... any suggestions?

What do you mean here? Thermostat out of it s housing - that should not be difficult. If you have stone build up in the housing that prevents thermostat form being taken out of the housing - this whole thing will not work. You must have space for coolant there. If it is plugged with stone, the coolant is not heating up the thermostat, nothing works then.

Or I misunderstood something?

The thermostat whould expand about 7mm, I measured it some time ago. My old thermostat was expanding only 5mm.

[col320ce]

Thanks for the thought on this Pawel ... I pulled it a few minutes ago and there was lots of rust build up in there. It was very hard to get out; clamped the housing in the vice and got vicegrips onto it. Bench tested just the thermostat and got about 6.5mm travel so it's actually probably ok.
I'll put it back and test it on Friday and I'll try mrfatboy's mirror suggestion if it doesn't cut off the air flow.
I feel I'm getting close!
Thanks again everyone

[Pawel66]

I truly think (which does not mean a lot due to my limited experience) that if you had coolant flow blocked by rust/stone build up inside the thermostat housing - it had no chance to work as it should have.

I think the later type of housing you can buy if it is difficult to clean it up.

[Benz Dr.]

I think early thermostat travel is supposed to be 1.1 mm or about .050'' so it's not that much.

R11 pump is only used on a 230SL. Each of the three engines used in our cars use a different pump due to fuel volume requirements and other factors.  The more displacement the engine has the more fuel is required to make it perform. So yes, I would be thinking about a R11 pump.

[FresnoBob]

At Mrfatboy's recommendation, I purchased an Innovate Motorsports A/F meter and have been pleased with its performance.  I've been able to get my idle mixture and rpm correct and check the A/F ratio under acceleration.

https://www.innovatemotorsports.com/products/lm2.php

[col320ce]

Latest update... All back together after cleaning out the rust and it still is not stopping the air. I'm going to pull it all out again and measure the travel required to push the plunger far enough to stop the air.  I assume I can add round washers to make this happen if I need a bit more movement. I also assume that to keep it balanced I would need to remove the same thickness of oval spacers that I added as round ones? I only have 2 very thin round spacers... Is there a "standard" total thickness range of these (I'm trying to work out if some have been removed).
Thanks!

[Pawel66]

Perhaps some help there: https://www.sl113.org/forums/index.php?topic=29221.msg212778#msg212778

[mrfatboy]

Oval shims adjust mixture during warm up only. 

Less oval shims = leaner
More oval shims = richer

Round shims adjusts the time when the WRD closes the air valve

Less round shims = later
More round shims = sooner


I seem to remember that there are usually 2 round shims.  I forget the thickness but I know it's been mentioned before here on the forum.

I never bought a new thermostat bulb before.  Does it come with a new spacer as seen in the below picture? I seem to remember there were two different thicknesses and they have to match. 

[mbzse]

.../...a new thermostat bulb before.  Does it come with a new spacer as seen in the below picture? I seem to remember there were two different thicknesses and they have to match

What needs to be correct is the opening in the washer (spacer) under the little thermostat so that the flange fits snugly. See attachment.
No sealing agent needed around this washer (spacer).
Use some, sparingly, on the conical flange between thermostat and thermostat "coolant housing" however.

Just a caution here: Never pull on the pin in the little thermostat; this is a sure way to disaster!

[mrfatboy]

Thanks Hans.  I knew there was something different about them😁


Here is another good read on shim thickness and general subject.

https://www.sl113.org/forums/index.php?topic=15863.0

[wwheeler]

I spent a lot of time adjusting the WRD with the round shims. The only thing they do is change the timing of when the WRD shuts off. The mixture is automatically changed by the device’s design. As it closes, it reduces the amount of fuel but also reduces the amount of air. You cannot change the mixture ratio via round shims.

I seem to recall I had two shims and was was about a 1mm thick. But that will be different between pumps. You just want enough shims to make the air shut off at the specified temperature. I think that is 150*F or 160 *F. Unfortunately, you just have to experiment. 

[col320ce]

I've done some bench testing and these are the results:
The thermostat shaft extension from housing in specified water temperature (with no load)
19.5mm    55^oC
19.5mm    60^oC
21mm       70^oC
22mm       75^oC (no further extension in hotter water)

It needs a small amount beyond this to fully shut off and in the car I don't think it's quite getting to full extension but I'm not sure how to prove this (I assume this is because of the load/resistance from where the pin below engages with the IP).  Is there a primary reference for what temperature the air will shut off at?  I've seen everywhere from 150-180 (about 65-80^oC).  So I needs say 0.5mm more regardless, but if it should shut off at 60^oC then I need to add about 3mm!

Both my shims look like 0.1mm so not helping much. I have 1mm washers that I can use and I can probably thin them if required too.  I also have another thermostat on order but being in Oz and Corona and that the rest of the order isn't ready to be shipped yet it might be some time before it arrives.  I'm kinda thinking I should just wait and see if it behaves differently.

Thanks again!

[wwheeler]

I just looked at my notes when I did all of this work. On my pump, it took a minimum of .7 mm worth of shims for the air valve to shut. But that was near 180*F (82*C). You do not want the shut off to be that close to the operating temperature. So, I have a total of 1.3 mm worth of round shims and it shuts off at around 160*F (70*C). The more you add, the lower the shut off temperature is. Simple as that. Another by product of adding round shims is that your cold idle speed will be a bit lower. That is because you are reducing BOTH air and fuel by altering the length of activation in the pump.

I do not think the actual shut off temperature is that critical, and just do what works best for your engine during warm up. I think if you set the shut off between 155*F and 165* (68*C - 75*), you should be fine.

[col320ce]

Something that I should have done earlier is get out my inferred thermometer. I'm getting the housing only to about 58^oC so I assume that I need to drive the car to get it warmer than this.  There is still some air flow at this temperature although it is almost off. I have 1.2mm of round shims in there.
So the real question is: Is 58^oC to cool to have it shut off? If not I'll just add some more round shims.  Otherwise stop what I'm doing until I can drive the car.

Jeff mentions 50-55^oC in post #21 of this thread: https://www.sl113.org/forums/index.php?topic=9244.0   I think this is in reference to the air shut off temp?

I am also a little confused about at what point the fip mixture is no longer being affected but the WRD.  I assume it is when the pin is fully extended but I'm not sure if the lever in the injection pump reaches its full setting before this.  I assume that I cannot sort idle out until the wrf/fip pin is a full extension ... therefore I need to get it up to 70^oC as this is when my pin is fully extended?

Thanks!!!

[mrfatboy]

During warm up the WRD feeler pin extends into the FIP leaning out the pump.  At the same time the air slide valve closes.

The feeler pin hits its stop BEFORE the air slide completely closes.

During this time,  the FIP is in a lean condition until the airslide completely closes and thus completes the full warm up cycle.

That's why you need that airslide to close for the next adjustment step (full operating temperature )

Having that airslide valve close just idling can take time. Sometimes it does take driving it to get to proper temp. I guess you might consider yourself lucky that your car runs cool😁