Pressure switch repair?

[Larry & Norma]

I have one bad and one not very good pressure switch.
I believe they are NLA (A00115421317).
Has anyone successfully cleaned/repaired these.

Am I correct in thinking that the only time, on an automatic without aircon, the CSS is NOT
activated is in neutral and park? (with engine running of course)

If this is the case I am thinking perhaps a micro switch or two on the selector lever correctly
placed will do the same job?
My car does not stall even 'tho the revs drop quite a bit, perhaps this will start to happen as the engine wears?

Just trying to think round the problem

[jacovdw]

Larry,

One possible way I can suggest to try and clean something that you obviously can't disassemble, is to spray some carburettor cleaner in to the switch via the threaded fitting.
It is possible that there might be some gelling of old ATF inside (or other gunk like brake band particulates) that is preventing the switch from functioning properly.

Alternatively, you can also try a solution of 50% acetone and 50% ATF.

I have not done this myself, but merely thinking out loud here as a similar method is used to try and clean the NLA brake light switches used on the pontons and early fintails.

[Shvegel]

Do a search. I could swear someone was just sourcing them.

[Sirasila]

That would be me. My switches have gone bad too.  I searched ebay and found only one listed as a transmission switch for a 300SE.  Well I bought it even though I need 2, and it arrived today.  I had my mechanic install it for the forward gear and it's working perfecty  
The best part of this was it cost me 95 dollars instead of the 179 dollar price I got through Mercedes. The only expensive thing seems to be the shipping cost to Thailand.
For the other one, I will try another item I also found on ebay which may or may not work, but if t does, I will let you know.  It seems to have the same basic function but a tad shorter. 
The switch seems to completely solve my idle problems, keeping the idle steady even with the AC on too.

[Larry & Norma]

Thanks for the replies, I will investigate cleaning/repair when i get round to taking them out.
Can they be bench tested?
What pressure are we talking about?

Interested in what you find out Sirasila

Larry

[Sirasila]

Larry,

One possible way I can suggest to try and clean something that you obviously can't disassemble, is to spray some carburettor cleaner in to the switch via the threaded fitting.
It is possible that there might be some gelling of old ATF inside (or other gunk like brake band particulates) that is preventing the switch from functioning properly.

Alternatively, you can also try a solution of 50% acetone and 50% ATF.

I have not done this myself, but merely thinking out loud here as a similar method is used to try and clean the NLA brake light switches used on the pontons and early fintails.

Wow.. I think I'll try the cleaning too for my reverse gear switch.  Since the forward gear now has a brand new one, it'll stay.
I think cleaning using your system may just work because the brake light switches from old Jaguars also use the same system and they sure do look similar.
I never thought of that. Thanks.

[jacovdw]

...Can they be bench tested?

The short answer is yes.

I am pretty sure that they can be bench tested in a similar way that the mechanical fuel injectors are tested for opening pressure although I have not done this myself.

One would connect a multimeter (set to check continuity) to the terminal and the metal body of the switch and then note the pressure at which the display of the multimeter changes.

...What pressure are we talking about?

I'm not exactly sure what the trip pressure for the switches would be. I can't imagine that it would be very high pressures required anyway.

I have been searching through my library of files and other bits of information, but have so far not found any pressure rating for these switches.

What I have found so far, are the different pressures as measured at the different test ports on the auto transmission for the different operating conditions.

I'll keep looking though.

[stickandrudderman]

Pressure at those switches is around 7 bar.
I've been thinking about an alternative as these switches are getting (like a lot of stuff) more and more difficult to source.
There are two ways to engineer a solution:
1. Source another pressure switch. This is relatively straight forward as you could locate the switch on the firewall and connect it with some braided hose, but unfortunately not good for originality if that's your thing.
2. Connect a relay to the wiring at the inhibitor switch and run the solenoid from that relay.

I haven't had to do either as yet but I'm sure the day is coming when I will have to.

[Larry & Norma]

Just removed my pressure switches. The totally inoperative one has a hole
in the casing caused by corrosion!
I suspect water has gotten in and ruined the contacts.
I will cut the end off and take a look at the workings some time.

[tel76]

When i put my car into reverse gear the solenoid operates, put it into forward gear and it does not operate the solenoid.
Which pressure  switches operate reverse or forward gears.

[Larry & Norma]

I think the forward one is on the passenger side of a RHD car.