'67 230SL CSV/ISV Wiring

[JamesHigdon]

So I'm getting REAL close on my hot start issues with my '67 230SL. Let me recap; timing is set at 30* BTDC at 3k rpm with no advance, the dwell is roughly 32-34* at idle, the car idles at around 900, the plugs are NGK WD7C equivalents, at its pulling 15 lbs/mg at idle vacuum.

The issue is the CSV is actuating when hot, flooding the motor and it won't start. If I unhook the switching wire to the CSV it'll start weak with no peddle but with 1/3 throttle it starts great everytime. The CSV is supposed to be on a thermoswitch, correct?

Also, the Injection Start Valve on the pump doesn't seem to do anything; it gets no power to it and when I put power to it nothing changes.

A wiring diagram for both would be great, my diagrams don't go back that far. Where is the CSV relay so I can look into it? I want to get this issues sorted without

[Tyler S]

James, If everything is wired correctly then most likely the thermal time switch is internally shorted. This would explain the CSV being energized with a hot engine. The "TSS" is located on the small coolant manifold on the drivers side of the head. It has 2 wires connected to it. It can be tested using a test light while cranking the engine (disconnect the ignition coil wire to keep engine from starting). One terminal will always have power while cranking hot or cold. The other terminal will only have power for about 5 seconds max when the engine is cranking cold. On a hot engine there should be no power from it. There is a variance in between dependant upon temp.

The enrichment solenoid is fed from the relay on the left fender well near the brake booster. If you are applying power (B+) to the enrichment solenoid directly and are not getting an audible click then the solenoid is either frozen or the internal coil is bad. It can be removed from the back of the pump via 4 screws.
The wiring diagrams are available in the manual section, beit you need to be a full member to access all of them.

http://www.sl113.org/wiki/Electrical/WiringDiagram

[JamesHigdon]

Ok, so the Thermal Timed Switch which controls the Cold Start Valve relay is mounted on the manifold off the driver's side of the head near the injection pump, correct? I pulled one wire off of it and the CSV still got power which to me indicated it had been bypassed to provide power to the CSV all the time, correct? Where is the CSV relay? I pulled the wiring to all three relays on the driver's side fender well near the brake booster and still got power to the CSV.

[JamesHigdon]

Very rarely working with cars do you get a "eureka" moment, well I got one today. Someone had pulled apart the connector for the CSV relay (the first one of the driver's side fender to the left of the master cylinder) and used small gauge wire to loop the starter signal wire into the relay to the CSV signal out of the relay. Not only was this causing the CSV to actuate every-time you cranked the motor but it was also causing the Injection Starting Valve on the pump NOT to actuate which caused an entertaining very lean then very rich symptom which was difficult to trace.

Do the next caretaker of your Pagoda a solid and put a tag in the glove-box with any modifications you've done so we know what to look for when trying to make the damned things run right!

[Benz Dr.]

So I'm getting REAL close on my hot start issues with my '67 230SL. Let me recap; timing is set at 30* BTDC at 3k rpm with no advance, the dwell is roughly 32-34* at idle, the car idles at around 900, the plugs are NGK WD7C equivalents, at its pulling 15 lbs/mg at idle vacuum.

The issue is the CSV is actuating when hot, flooding the motor and it won't start. If I unhook the switching wire to the CSV it'll start weak with no peddle but with 1/3 throttle it starts great everytime. The CSV is supposed to be on a thermoswitch, correct?

Also, the Injection Start Valve on the pump doesn't seem to do anything; it gets no power to it and when I put power to it nothing changes.



A wiring diagram for both would be great, my diagrams don't go back that far. Where is the CSV relay so I can look into it? I want to get this issues sorted without

Set your timing to 38 degrees BTDC @ 3,000 RPM with vacuum line connected.
Dwell should be more like 36 - 38 degrees.
NGK BP5ES which are about the same as W9DC is what I use. W7DC ( what it calls for ) is generally too cold.
15 inches of manifold vacuum is on the low side. 18 - 20 inches is more what you should be looking for.
Make sure your coil wire is metal and not carbon. New Bosch sets come this way and need to be corrected.
Spark plug terminal ends should be 1K ohms. I prefer to have no other resistors in the high tension system.

[JamesHigdon]

Well it all worked for about 30 minutes and now the relay won't actuate! I know only members can get to the wiring diagrams but a hint would be good. I'm getting power to both post 85 and 86 on the CSV relay which obviously won't work...which one should have ground coming to it? I'm looking at what diagrams I can access and it appears the time delay switch is supposed to feed ground to terminal 85 when cranking, correct? If I'm getting power there I assume that means my time delay switch has given up...

[Tyler S]

James, There is no permanent ground supplied to the CSV relay. It gets its ground through the TSS which is grounded to the engine block through the small coolant manifold. This only happens when cold and only for a few seconds. Keep in mind if the engine is hot when testing you wont see the ground. You will see power on both sides. This is because power is backfeeding through the coil of the relay. The TTS is also a thermistor in that it creates its own heat. Your engine could be stone cold but if you have been repeatedly cranking it then the sensor itself is hot and needs to cool down. Have seen it take longer than 15 minutes before it will function again. This keeps the engine from being flooded on multiple start attempts. One more thing is that the entire circuit needs to be connected and "under load" for the TTS to function properly.
If you have the correct glovebox owners manual for the car then there is a wiring diagram in it. It's the only foldout in the entire manual so should be easy to find. There is also a simplified diagram of the starting aids at the very beginning of part "III Technical Information "

[JamesHigdon]

I joined as a full member and have access to the diagrams now, I will check to see if the manual came with the paperwork we have for the car. After going through the diagram for my car it appears that both the TSS and the Time Delay Relay can provide ground to the relay; checking my TSS it provides ground up until the key is turned to crank and then goes to power even when the vehicle is dead cold so I suspect the TSS is stuck closed. My Time Delay Relay is also not working so I need to looking into that. Thanks!

One more question, with the time delay relay working the car will always get one second of CSV and Injection Start Solenoid activation even when hot, is that correct?

[Tyler S]

Yes the time delay relay should privide 1 second regardless of engine temp.
Also I have found that the wiring diagrams in the manual section here can have discrepancies so use them more as a guide.

[ja17]

James, start by identify which starting system you have on your car. I suspect it is "Version III " for the late 230SL.  With this version, you  should have one rectangular relay and one round time relay. You will also have the thermo time switch on the engine. If yours is "version III", look at the chart for "Version III" use a 12 volt test light and check to see if the injection pump solenoid and the intake starting valve are energized according to the chart. If your(round) time relay is not working, open it up and clean the contacts. Notice the adjustment screw inside for adjusting the time interval. Get the round time relay working before attempting any adjustment on the interval.

[Shvegel]

James,
Just to clarify the function of the thermo time switch it provides a ground for the cold start injector and not power.  there are two terminals on the thermo time switch.  The first provides a ground to the engine when the switch is below 35 degrees C.  The second is a heater that heats the switch internally. The heater grounds to the engine as well.  this heater is the "Time" function of the switch as it takes the heater aproximatly 9,5 seconds to heat the switch and turn off the ground at the other terminal.  This is all on a sliding scale and a warmer switch will take less time to turn the ground off.

[ja17]

As you probably know Pat, the thermo time switch also senses the engine coolant temperature. This is what creates the time variation of the cold start valve during cold starting. The colder the temperature of the coolant, the longer the valve stays active on a cold start.

[Shvegel]

Joe,
Yes, that is my understanding as well. Little suckers drove me nuts until I finally figured out how they worked.  The typical diagnostic hangup that tripped me up years ago was looking for power at the cold start injector and assuming all was good.