Author Topic: Slow (or weak) CSS  (Read 4381 times)

jedwards

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Slow (or weak) CSS
« on: May 14, 2014, 06:06:17 »
Gentlemen,
My Constant Speed Solenoid or CSS  on my early 250SL Auto,  comes on rather slowly,  over a 2 second period.  Is this normal?
I appreciate that it has a lot of work  to do in moving their entire accelerator linkage mechanism, but if its is slow, it might also be weak, somewhat explaining my in gear idle variability.

Should it slam on like normal solenoids, or is it a supposed to be a more gentle process?  Is there a technique for testing it?
Does anyone know how to dismantle a CSS?  If I can get it apart, I can rewind and restore it.

Many thanks in advance.

ctaylor738

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Re: Slow (or weak) CSS
« Reply #1 on: May 14, 2014, 11:49:04 »
IME, it is instantaneous, as soon as it gets power via the pressure switches on the transmission.  The switches rather than the CSS may be the problem.  Is there less of a problem in reverse vs. forward?
Chuck Taylor
1963 230SL #00133
1970 280SL #13027 (restored and sold)
1966 230SL #15274 (sold)
1970 280SL #14076 (sold)
Falls Church VA

Cees Klumper

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Re: Slow (or weak) CSS
« Reply #2 on: May 14, 2014, 16:32:56 »
It should be immediate. Not sure how you would open one up but if you figure out an economic procedure to restore these, it would be very welcome to the Pagoda community.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

jedwards

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Re: Slow (or weak) CSS
« Reply #3 on: May 15, 2014, 00:33:59 »
Thanks for the help.

Where is the pressure switch located?
Is there a test procedure or method for the switch to determine if it is working properly?

wwheeler

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Re: Slow (or weak) CSS
« Reply #4 on: May 15, 2014, 19:45:17 »
You also might look at the linkage and make sure it is well lubricated. There are a couple of bell cranks especially the one below the manifold that get sticky over time. I ususally oil the entire linkage once a year. I use a micro oiler to get into the tiny crevices.

My CSS is immediate as well. In fact when I shift into gear, the idle speed doesn't change at all.
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6

ctaylor738

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Re: Slow (or weak) CSS
« Reply #5 on: May 16, 2014, 01:03:30 »
There are two pressures switches, one for forward and one for reverse.  They are located on the lower front sides of the trans.  They both have metal lines and wires running to them.
Chuck Taylor
1963 230SL #00133
1970 280SL #13027 (restored and sold)
1966 230SL #15274 (sold)
1970 280SL #14076 (sold)
Falls Church VA

wwheeler

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Re: Slow (or weak) CSS
« Reply #6 on: May 16, 2014, 16:46:34 »
Sorry, I didn't see the question about how to test. The switches work by providing a ground when pressurized. So take off the lead wire and you can test to see if the post has a ground when the switch is pressurized. The switch body is grounded by the trans housing. Make sure your ground wire to the trans is good.

Might run a jumper wire to the post so you don't have to climb under the car when its running.
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6

ctaylor738

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Re: Slow (or weak) CSS
« Reply #7 on: May 16, 2014, 19:21:32 »
Running, and in gear!  Not a good time to be under the car.
Chuck Taylor
1963 230SL #00133
1970 280SL #13027 (restored and sold)
1966 230SL #15274 (sold)
1970 280SL #14076 (sold)
Falls Church VA