Author Topic: Do I need to replace my constant speed solenoid?  (Read 1425 times)

sgp

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Do I need to replace my constant speed solenoid?
« on: December 02, 2022, 21:35:13 »
Hi folks!

So here's a question for you:

Do I need to replace my 000-072-01-00 constant speed solenoid?


Background:
My 250sl automatic has had some idling issues ever since I bought it 5 years ago. These issues can be summarized as a loss of power and cut-offs after driving it for more than 15-20 minutes (it works well in N and in P). When I get to a stop sign or a red light the car's rpms drop and it starts to cut-off unless I accelerate it. Sometimes, specially in hot weather the car just doesn't turn on or cuts off very easily at a stop. Not to mention the car completely cut offs when I put in reverse backing into my garage after driving it for 15-20 min. I regularly have to manually push it to its parking spot after a drive.

Yesterday I took my car to Mercedes tech who is a friend and he fiddled around with the solenoid tightening some of its screws. Immediately I felt the car perform much better. Today I took it out for an hour drive around town in morning rush hour traffic to test if these "fixes" worked. The car performed very well during the first 40 minutes in stop and go traffic but on the way home I felt it begin to lose power when accelerating it off the line from a red light. Then when I got home and tried parking it in reverse it completely cut off again.

The car is behaving "better" and withstanding longer drives after my friend fiddled with it. However it still cuts-off and is not reliable as I would like to be. So I ask again: Do I need to replace my 000-072-01-00 constant speed solenoid?

Thanks  :)

< Picture of the CSS attached >



Cees Klumper

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Re: Do I need to replace my constant speed solenoid?
« Reply #1 on: December 03, 2022, 00:31:57 »
From what you describe it sounds like you have more issues than only the constant speed solenoid. Especially the 'losing power after longer drives'. You can check the functioning of the solenoid by having a helper put the car in drive or reverse. while idling (foot on the brake) and you can see whether the solenoid is able to push the linkage enough to maintain the idle speed (should be around 700-800 RPM I believe).
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

rwmastel

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Re: Do I need to replace my constant speed solenoid?
« Reply #2 on: December 03, 2022, 02:12:26 »
... but on the way home I felt it begin to lose power when accelerating it off the line from a red light.
Cees is right, other issues at play here. This particular symptom has nothing to do with the CSS.
Rodd

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2017 C43 AMG
2006 Wrangler Rubicon
1980 450SL
1966 230SL

lpeterssen

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Re: Do I need to replace my constant speed solenoid?
« Reply #3 on: December 03, 2022, 14:47:18 »
Dear SGP

I agree with Cees and rwmastel.  The issues described does not have to do with the CSS (Constant Speed Selenoid). 

Yor gave two clues that are important.

1. Hesitation to start engine when hot
2. Loss of power when accelerating.

The first thing I would go after is the fuel delivery system.

a. Check with proper instrumentation Fuel delivery pressure at the inlet of the mechanical fuel injection.  Go to amazon to buy a pressure gauge.  If I am not mistaken it should be around 4 bar.  Check out value on the pagoda forum technical section.

b. Hesitation to start in hot is always related to a low fuel pressure at delivery point.  If pressure is not high enough, specially on hot weather, fuel evaporates causing VAPOR LOCK.

c.  Check condition of the fuel filter at the engine bay on lower left bumper at the front of the engine.

Best regards

L.peterssen
« Last Edit: December 03, 2022, 15:22:24 by lpeterssen »

sgp

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Re: Do I need to replace my constant speed solenoid?
« Reply #4 on: December 03, 2022, 14:59:00 »
Thank you all for your great feedback and recommendations.

lpeterssen

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Re: Do I need to replace my constant speed solenoid?
« Reply #5 on: December 03, 2022, 15:27:06 »
I am pretty sure that problem is related to a tired fuel pump at the trunk.  It has happened to me many times.  In that case pump needs to be replaced for a new one, or you can try first as this is an expensive item, to buy the rebuilt kits that are listed on Ebay by some Mercedes Classic specialized vendors.  During the process of repairing the pump, new seals, new bearings and new carbon brushes are installed.  This later ones will dramatically affect the speed at which the pump spins and therefore you will have a greater output  flowrate and pressure .  Maybe if the armature is OK it can be rebuild.

rwmastel

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Re: Do I need to replace my constant speed solenoid?
« Reply #6 on: December 03, 2022, 23:46:22 »
I am pretty sure that problem is related to a tired fuel pump at the trunk.  It has happened to me many times.
Don't just go changing parts without testing. Collect facts (test results) and then decide what to do.
Rodd

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2017 C43 AMG
2006 Wrangler Rubicon
1980 450SL
1966 230SL

lpeterssen

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Re: Do I need to replace my constant speed solenoid?
« Reply #7 on: December 04, 2022, 11:35:39 »
Yes I agree, first buy the fuel pressure gauge kit, and measure values after the fuel filter and compare against specs listed on the technical section of the forum.  Do that on a cold engine, and also after 30 minutes of driving on a hot hot day.

lpeterssen

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Re: Do I need to replace my constant speed solenoid?
« Reply #8 on: December 04, 2022, 11:40:24 »
Here what you need to accomplish the job
Fuel pressure testing kit

BETOOLL HW0138 0-140PSI kit de herramientas para el auto con medidor de presión de la bomba de inyección de combustible. https://a.co/d/1I9pOYV

teahead

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Re: Do I need to replace my constant speed solenoid?
« Reply #9 on: January 04, 2023, 20:51:00 »
try the linkage tour (adjustment)
1970 280SL auto, AC - aka "Edelweiss"