Adjusting the 2 (?) second Time Relay

[hands_aus]

Has anybody ever adjusted their 2 Second Time Relay?

I have an old second hand relay that didn’t work.

The contacts did not meet so I tightened the adjusting screw until they did. To do this I connected my multimeter to the contacts and watched the reading go from zero to about 3 ohms.

When I tested the relay, the heating coil opened the contacts instantaneously.
I am not sure how long it is supposed to be activated but as the name says 2 seconds I adjusted the screw until the contacts open after 2 seconds.

If I apply 12V across the heating coil for too long (3-4 seconds) it starts to smoke.
I was wondering if there might have been some “gunk” on the heating element that was burning off. Maybe there is a resistance to limit the voltage in the coil but I don’t see one.

I checked the 230SL wiring diagram and it shows that there are 3 wires (including an earth wire) to it.
The heating coil is across pins #86 (gets 12V +ve from ignition sw) and #31 (earth), the “break” contact is across pins #85 and #31.

The “Break” contact provides a parallel contact across the Thermo Time Switch when the TTS is above 35C operating temperature.

From my reading of the 230SL wiring diagram, the heating coil has 12V applied to it all the time the ignition switch is turned to “START” position, just like the TTS.
Given that, I imagine that in reality the coil won’t burn out because it was designed to operate this way. Unless it has been burnt already.

It is worrying to see little puffs of smoke coming from the coil. Of course this is not visible when the cover is on the relay unit.

What happens when the car takes longer to start?

Questions………

How long should the 2 Second Relay operate for?

How long can the 2 second Relay operate for before burning out?

On some 230SLs the 2 Second Time Relay was wired in as standard but others and later models it was optional.
For the optional wiring harness MB must make a piggy-back type connection.

Does anybody know what the harness connections look like?

I figure they must be “plug and play” to use modern terms.

Pics would be appreciated thanks.

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Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

The heater on the relay is energized as long as starter sw. is closed.  [Same as TTS ]. This is a low ampereage heater, so it should be able to stay in the circuit for long cranks. However, when one is using the starter for repair work [ ie., compression testing, valve adjust, etc] , one can remove fuse # 6 to deactivate these heater circuits, which will  also, at the same time, deactivate the CSV fom squirting unwanted fuel into the intake while test are performed....

[hands_aus]

Hey Arthur,

Thanks for the info.

Does anybody know about the optional wiring harness plug ends?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

The harness part # is 108 540 10 09.
 This is the harness that allows addition of 1 sec modification kit.  Relay used is 001 545 16 24.
 Same can be accomplished with cabin momentary push button switch..

[hands_aus]

Hello Arthur,
Thanks again for the info.
I already have a wired-in push button switch. It works great.

QUESTION......

Should the Time Relay operate for ONE or TWO seconds?

Background.......
2.5 years ago I bought a batch of used relays out of a 250SE sedan. Included was the time relay. I cut the wiring harness and bought the plug ends and wiring too. The time relay was wired in to the harness.

Reason for doing this job.....
I was having a quiet day so I thought I would try to use the correct relay to start the car automatically.

Doing the job....
The correct coloured wires (I looked in the 1959 service manual) were in the harness.
Using correct MB wires and plastic tubing I made my own additional harness for the time relay.

(pink with yellow stripe, #85 to #85 on the Cold start Relay)
(pink with yellow and black stripes, #86 to #86 on Cold start Relay)
(brown #31 to earth)

I used one of the plugs for the Time Relay end but to make the connections to the Cold Start Relay I made small loops in the wires and fitted them over the pins and tightened them, then pushed the plug on until it clicked.

This arrangement works but is non-standard, that is why I was enquiring about the plug ends of the optional wiring harness.

The other non-standard feature is that I have earthed the time relay at one of the relay mounting screws that goes into the car body. MB would have provided an earth  wire in the main harness.

To isolate the time relay I just have to unplug it and the car will be back to normal.

Testing the relay.......
After installing the Time Relay I connected a small 12V test light to the Cold Start Valve.
The car started right up with the test light ON for about 2 seconds.

I let the engine warm up for a while so that the temperature would be above ThermoTimeSwitch operating temperature.
Then I stopped the car and restarted it. The test light was ON just as it should be.

I repeated the process and it worked each time.
I don't anticipate any problems when I run the car on the road.

The weather here has been crook so I will have to wait until it improves.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

The relay has always been a 1 sec relay to my knowledge.
The actual mod was a later design for cars that had hot start problems.  There were 3 versions of CSV circuits and 2 mods that I know of , but I always thought the time was 1 sec on all...maybe the early original version used a 2 sec
 The mod harness is just a pigggy back set up and a ground just as you have done. The other mod is to eliminate the wiring to the early thermo switch sensor. They leave the sensor to keep the coolant secure, but eliminate that circuit by rewiring back to the TTS.
That mod is only for the very early circuits with the lower temp TTS.
 What is the part # on the one you said is marked 2 secs??
 I think at high ambient temps , 2 secs could cause some flodding..
My preference has always been a cabin sw cuz I know if the engine wants gas or not and for how long....I am the Sensor.

[hands_aus]

The part number on the outside of the case has disappeared but the numbers on the bottom are SH/VT2/12/2   12V

My 250sl had both CSV relay and CSS and relay.

In summer my car starts easily if the time between turn off and restart is not too long. However if I leave it for a couple of hours the temperature has not reduced enough to bring the TTS into working range. Then it takes a bit of cranking.

I will adjust the time to be one second. It is better to have less fuel and not run the risk of flooding.

The cabin switch will stay.

Thanks for your help

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Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

<<My 250sl had both CSV relay and CSS and relay.
>>

 Yes , that was the later system .  The second relay was so they could operate the CSS independantly from the CSV for rack inrichment regardless of coolant temp. This system did away with the earlier 1 sec time switch, which I prefer.
 Again, cabin sw in parallel with any of the versions gives you system over-ride without changing any circuit...

[A Dalton]

<<However if I leave it for a couple of hours the temperature has not reduced enough to bring the TTS into working range. Then it takes a bit of cranking.
<<
 This is where the cabin setup comes in handy.
 Usually, this complaint means that the check valves at the pump pressure lines is leaking back and the pump has to re-pressurize the
lines.  CSV manual squirt over-rides [and masks] the condition.
 The true fault can be retified by changing the check valves [ Early cone valves were replaced with better sealing ball valves].
 common complaint on early  oil resirvoir pumps.
 I have a friend who also has spent some time on Bosch MFI and he installed a flasher between the CSV and starter feed circuit and said it worked great. I believe it was on an Early 108.  The theory is to let the CSV pulse on/off at a frequency regardless of any temp conditions.. Starter energized, squirter pulse ..Interesting concept , if nothing else...........

[hands_aus]

>>> The true fault can be retified by changing the check valves [ Early cone valves were replaced with better sealing ball valves].
 common complaint on early  oil resirvoir pumps.
>>>>

Is it a big job to replace the check valves on the injection pump? Could I try to do it or can it be done by a MB mechanic or does it need to be done when having the inj pump rebuilt?
Do you think it will be alright to use the car for a prolonged period like it now is with the Time relay installed?

>>>>he installed a flasher between the CSV and starter feed circuit>>
Did he use a flasher relay instead of the 1 second Time relay?
It would achieve the same thing as long as it was disconnected when the starter circuit was released.
Probably the flasher relay was about one tenth the price of the Time relay..... might have been an old one laying around.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

The improved ball valves are MB part 000 074 17 15.
 I had an article on it , but can not find it at the moment, as I just relocated. Not a big job...
 Not a big deal and most  just live with it..as it does not affect running and can be overcome with CSV activation.
  The flasher/pulse relay was just something he mentioned in passing . The idea is to get a pulse rather than a constant stream from the CVS , allowing a small laps between squirts for the engine to catch..could be an improvement , but I never tried it.. seems logical. I may just fool with it when I have time to play...

[hands_aus]

Arthur,
I reduced the operating time to 1 second and when I went out today, the car fired right up every time.
With the 2 second adjustment the engine faltered just a little bit because of too much fuel, but with the 1 second squirt it doesn't falter.
It is very satisfying.

Thanks for that part number I have added it to my parts number spreadsheet.

Sometimes I see things like pistons, injectors or valve seals for my 250SL on eBay and I wonder if I should invest in them.

Thanks

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

That should do it.
 You have the manual over-ride anyway.. and most who do install one get to know their cars starting characteristics to a "T" after a while
[ I call it the "Formula' ]
 Kinda like the old hand choke autos of yesteryear..ya just got to know what each one liked....
 Anyway, the most important maint. on the early pumps is frequent oil res. changing and dip-stick checks... too bad it is such a pain to evacuate them ... I have a sealed jar with a vac line so it is now easy, so you may want to use that method.
 Surprising  how many guys I talk to that don't even know their cars pump has an oil level maint. check.. the car is shinny as hell, but the pump is dry...

[hands_aus]

[quote the car is shinny as hell, but the pump is dry...
[/quote]

Not this one

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

Arthur,

quote:the most important maint. on the early pumps is frequent oil res. changing and dip-stick checks...

How often do you change the oil?
I've had my 230 4 years but done maybe 3000 miles. Pump was newly rebuilt then.

naj


65 230SL
68 280SL

[A Dalton]

Naj
 I don't use a milage interval to gauge when to change pump oil , but rather , I check for dis-coloration [ meaning dirt] and I smell it .. if it has a strong gas odor , you want to change it.
 Although the later pumps had crankcase oil feed and this extra res. does not have to be looked after, many Techs I know think that
 the old res pumps got better/cleaner lube cuz crankcase oils are way dirtier and comtain both gas blowby/carbon  and sulphur. They also have a higher moisture content which can cause freeze up in Winter Climates .
 It is best to check the dip after a warm run , as you get a truer check of oil condition than if you just check it cold cuz the dirt will settle on the cavity bottom on a cold, standing pump....

[Naj ✝︎]

Thanks for the tip, Arthur  

naj

65 230SL
68 280SL