Coupe died when put in reverse

[Marrs]

I remember a post on the W113 section where somebody mentioned that a car that stalls when put in gear, in my case reverse, an be due to a solenoid switch that is on the transmission. I believe they stated there was one for forward gears and a separate solenoid on the other side for reverse, does this also apply to my '62 220se? If I do have a reverse solenoid on the transmission can I access it from below without dropping the trans, or is there an access door on my tunnel like on a W113 so I can get to it from inside the car?

This only happened once yesterday when I was back home and putting her in her parking space, no issues in forward gears. I am going out right now to do some more driving and try to pay attention to idle speeds, any drops or other issues with forward gears, etc. I will report if there is additional info to add. Any and all advice is appreciated!

Update after drive: The car seems normal but I did notice that when I put her in reverse the idle, which usually stays at 750, spikes slightly to 850 then drops to around 650 before settling back at 750. This happens in less than a second or two. I also had no problems with the car stalling out this time. Do you think it just dropped idle a bit too low that day for whatever reason and was just an anomaly? Am I within the idle ranges you guys are for a 220se?

[GGR]

If your car idles at 7,500 rpm I think you have other issues  .

[wwheeler]

Idle speed for an automatic should be the same in gear and out - 750-800 RPM range. Hopefully, your stated RPM is a typo. The idle speed in gear is bumped up by the idle solenoid on the intake manifold. There are (2) switches on either side of the trans that tell the solenoid that it is either in drive or in reverse. One switch is for reverse and the other is for drive. Can't remember which side is which right now. The switch creates a ground for the solenoid. They do fail from time to time. You can check to see if your solenoid moves out (with force) when trans is in gear. If not, could be switches, wiring and the solenoid itself.

[Marrs]

If your car idles at 7,500 rpm I think you have other issues.

Ha, I couldn't stop laughing at that... yes I was running some numbers for another project before I posted and my mind was apparently still stuck in "thousands", I promise my car is not fitted with a Formula-1 engine.   I have edited to correct those figures.

Thanks for the tips.

[stickandrudderman]

Be aware that the hydraulic grounding switches will only work with the engine running so checking for correct function is best done with a helper.
Have the engine running and then get your helper to select drive or reverse. You should observe the solenoid extending to open the throtte a liitle to compensate for the extra load created by the transmission. If it works in drive but not in reverse then it is likely that the relevant hydraulic switch has indeed failed.
If it works in neither then you need to start a more thorough investigation.
Hydraulic switches are becoming more regular failures with the passing of time and they are getting very difficult to source.
Somewhere in my office I have the beginnings of some research I did a while back to try and find a substitute hydraulic switch but the current load is quite high and so some lateral thinking was required.

[Marrs]

Does the W111 have an access port in the transmission tunnel in the passenger area or do I need to lift the car to observe?

[wwheeler]

Yes, the W111 has the access plate on the passenger side trans tunnel. But that is to access the 3 position solenoid and top starter bolt. The 3 position solenoid controls the trans oil pressure for shifting. Nothing to do with idle speed. See attached picture courtesy of JA17. 3 position solenoid is on top just behind bell housing.

What you are after are the throttle solenoid switches. Those are located on the forward, bottom side. In this picture, it is just above the "22mm" locknut lettering. It is a silver hexagonal shape and is about 2" long. There is one on either side. A wire goes over the trans and connects the two. Those two switches are what you need to test.   

[Marrs]

That's very useful, thanks!

[ja17]

That fact that your idle increases in rpms, before the decrease in rpms, leads me to believe that you do have a hydraulic switch and it is working or trying to work. Your problem may just be an adjustment of linkage, timing, fuel mixture,and/ or idle solenoid.  You need to view the working of the idle solenoid on the intake and report back to us. You will need a helper with one person inside the car tending the brakes and working the shift lever.

[Marrs]

Hi and thanks, I actually just learned about the full function of that idle servo recently. I actually just dropped my coupe at the shop for a new Metric Motors head since I had put that off last summer and want her to be 100%, so they will set the car up again when finished and I will be sure they note this issue specifically. Thanks!