Automatic transmission- Car turns off in D or R

[SEB]

My friend has a problem with the automatic transmission in a 230SL and asks for help:
The car turns off after inserting the D or R
Electro 3 position magnet in working order. Oil and filter were changed.

He checked the oil pressure at idle (without vacuum and in position 0) is 120 psi after removing the adjustment screw it drops to 90 and the adjustment ends.

The photo shows where the sensor was connected. Is it the right place?

What can be the reason?
Many thanks in advance for any help

[Pawel66]

Adjustment of idle at the Constant Speed Solenoid - that is where I would start.

If it is both D and R - it may not be the switches or both of them gone bad. So solenoid itself, its connections or adjustment.

[SEB]

Many thanks Pawel! And what about the place where he is testing the presure? Is this OK?

[Pawel66]

I am attaching the picture with port (I think it is this one). You have to disconnect the vacuum. By the way, check if you have vacuum there (15 inches). You should have ca 40psi modulator pressure at idle, vacuum disconnected.

It may be that there is not enough pressure to activate the switch to increase idle, but then you would feel it while driving.

But: I would check the Constant Speed Solenoid operation and adjustment first. Do you know how to do that?

[SEB]

Pawel I will pass this information to him and will come back to you.

[SEB]

Hello Pawel
I got feedback from my friend, he is a little lost a he has following questions:
1.   Do you know how to check the Electromagnet?
2.   Is the place where he is checking the Pressure the right place?

Many thanks
Sebastian

[Pawel66]

Seba, it is difficult to say from his picture. I sent in previous post a picture of the gearbox with port marked, tell him to verify.

On the magnet (picture attached): the most common system of increasing idle to prevent engine from stalling when gear is selected is the Constant Speed Solenoid (but not the only system!). It is a cylindrical solenoid on inlet manifold that pushes linkage when gear is selected to increase idle. As an effect, if adjusted correctly, the idle does not change when gear is selected. This solenoid is activated by two pressure switches on left and right hand side of the gearbox (one for R, one for D). They provide ground to solenoid. When someone is in the car, with engine running, press the brake and have someone else watch the solenoid and linkage as gear is selected. Solenoid should activate and push linkage. If it does not, the simplest way to check the solenoid is to check which contact is power (after ignition) and provide ground to the other contact. If it works and pushes the linkage, it means something is preventing ground to get to it from the switches. These can be bad switches or wiring.

If solenoid works, but is not pushing linkage enough, it can be adjusted by turning the nut on its shaft.

I suggest if your friend gets to measurements of modulator pressure, it would be good if he finds appropriate literature.

The constant speed solenoid adjustment is the last step in tuning the car. There are many things that should be done before. You have a lot on that on the forum.

It is all described in Technical Manual, but you have to be  Member to access it. Relevant part is called Linkage Tour and there is a piece on automatic transmission too. Otherwise - need to search through posts for details.

[SEB]

Many thanks Pawel. He got more or less the point and will tomorrow work on this- so I will let you know if he was sucessfull

[Pawel66]

Here you have a handful of data:

https://www.sl113.org/forums/index.php?topic=30821.0;topicseen

[SEB]

Hi Pawel. An update from my firend. He go trough all this information but still could not solve the problem. Do all automatic transmissions had the elektromagnets? He has one without any electromagnet on the body of the box. He has an old version of this gearbox. Thanks!
Sebastian

[Pawel66]

I have read in the Technical Manual, that on early models there was a hydraulic device installed to keep the idle constant. It was referred to as helping the engine when power steering was installed as using power steering is putting load on engine too. So I am not sure if there is this hydraulic device that helps idle when gear is selected - beyond my knowledge.

What i have also read was that when engine is properly tuned, it should not, actually, stall when you select a gear.

Sorry...

[Cees Klumper]

The 'elektromagnet' is not on the transmission, it's on top of the engine, sort of, on the passenger side. If you search the forums on 'constant speed solenoid' (or CSS) you will find tons of info on how it is supposed to work and how to adjust it. It could be that it is not hooked up properly, or it lost its 'strength', or it needs adjusting, or one of the switches that activate it on the transmission is defective. That all said, I am not sure that the 230 SL had a CSS installed, or just a 'dashpot'.

[Pawel66]

Thank you Cees.

On the picture I attached to the previous post I marked the Constant Speed Solenoid with a circle. Indeed it is not on the transmission. Just the switches are on transmission.

If you have the switches, perhaps the car had the CSS magnet. Maybe it has a bracket for it.

The dashpot - I thought it was more to avoid sudden rpm drop with manual transmission, but I may be wrong. I am afraid I do not know enough on dashpot function and on the hydraulic device functioning to help. I am not sure how the idle was supported in early 230SL if the magnet was not there.

I am attaching a picture with arrow showing the switch - close to the front of the gear box. There are two switches on both sides of the transmission, one for D, one for R.

[SEB]

Hello Cees,
Hello Pawel,
many thanks for the inputs. Unfortunately my friend is still lost with his problem.
Below his description of this situation:
"The engine is set at 800 rpm CO 3.5 Ignition rate set at 30 degrees at 3000 rpm, the pressure in the box set engine after selecting D or R continues to go out. If you can move the box very nicely switches gears and there are no problems. Today I had contact with Sebastian's 250SE engine in which the electrical systems did not work, although the revs dropped a little and the engine was working after choosing D or R. Maybe the modulator of the gearbox or some other ideas are incorrectly assembled.
Thank you in advance for your help".
Maybe you have some ideas?
Many thanks!
Sebastian

[Pawel66]

This is far ahead of the front line of my knowledge.

If it were my car in my garage:
1. I would check if the switches are on the gear box and if the wires are there.
2. If the solenoid is not there - is there a bracket left or anything that suggests the it was there but it is removed
3. The hydraulic device for idle increase is not there and was never there is there a Power Steering or AC?

If it is a no, no, no - I would make sure the engine is in good tune:
1. Ignition timing (and I do not know values for 230Sl at idle - may want to check in Wiki)
2. Valve clearances
3. Dwell
4. Richer idle - I would go for 5 or 5,5%
5. Maybe higher idle

The Gurus say that well tuned engine should cope with gear in condition....