Hot/warm start mystery!

[Greg]

I know that this topic is discussed several times in the forum but after going through all what everyone has to say still I cannot see where the problem is once and for all. Please help! if you have solved the problem.
My 230sl start great in the morning no gas pedal is pressed just turn key and POOF!! there she goes. If I turn the car off after some seconds and try again, no problem again. But if I drive for about 5 minutes, turn off car and wait. Cannot start again. Yes if I press full gas and leave the ignition on for 8-10 seconds it will start again (sometimes). But there I have just one chance. If something goes slightly slightly wrong during the press the full gas procedure, then there I had it. Car wont start again until the next day. What the heck is going on? Any emergency tips? Usually if I am with someone else I can push the car and it will start.
I have tried to connect the solenoid with a switch when hot start to control more fuel but no help. Fuel accumulates in the hose between the manifold and the air filter. It get full of fuel, and quite a lot.
It seems that only the early 230sl cars suffers from this. Why? Where is the difference from the other models?

Did anyone solved the mystery, please give me the correct answer. Thinking of selling this car now, she is just embarrassing me in front of crowds all the time. Typical when I am somewhere important, she wont start.

Very sad : (

Greg

[enochbell]

Greg,

Been there, done that.  The starting circuit and valve control on hot and cold start for the early 230sl is different and, in my experience, inferior to the later W113's. There are complicated fixes and and an easy fix.  The easy fix is to install a momentary switch to control the CSV (the valve that sprays a bit of priming gas on cold start, located in the front end of the intake manifold) so that you can actuate the valve while cranking the motor on hot starts.  With a little practice you can time the length of actuation just right and never worry about hot starts again. 

Best,
another Greg

[Greg]

Thanks for your reply another Greg,

I have just a few questions about the easy fix and the momentary switch conected to the csv. Do you press the switch before key is turned or you turn key until you hear the pump and then press switch or when car is trying to start and key is on? How long should I press the switch? How many times? Should I use the full gas pedal method when using the switch? Because I think it can easily be over flodded.

Many thanks again
Greg

[enochbell]

I think every 230sl will be a bit different but, for mine, I turn the key and immediately actuate the CSV for just over 1 second.  The car starts right up.  I do not give any throttle until it catches, then I go to the floor until I get a strong idle, then I back off.  Hope that helps.

g

[franjo_66]

Greg,
I had the same frustration as you!
The injector pump, injectors & CSV all overhauled by Gus at Pacific Fuel.
Cold starts are perfect, but hot starts as per your description.
However, i experimented with the throttle depressed and with many different scenarios (eg full, half, 3/4, etc) i found that 1/3 travel of the gas pedal on hot starts gives me a perfect start every time?!
Probably varies from car to car, but may be worth a try.
Good luck and don't sell!!!! It's all part of the "charm"
Rgds
Franjo

[Greg]

Thanks guys for your help. Today I will install the switch and try it out on a safe place.  Its a plus to hear that this is a very common problem.  I would like to ask about the red oil cap on the injection pump. How much oil should I fill and what type of oil?

[enochbell]

Greg,

The quirky injection pump oil sump on our early W113 is a subject covered elsewhere.  Here is one thread:
http://www.sl113.org/forums/index.php?topic=18226.0
Although it is not specifically addressed, I assume you should use the same oil in the pump as used in the engine.

g

[hands_aus]

I thought the 230sl had a 'time relay' which operates for one second each time the car is started.

[66andBlue]

...How much oil should I fill and what type of oil?

Check the level with Paul's tool: http://www.sl113.org/forums/index.php?topic=18226

[enochbell]

There are several versions of the thermo and thermo-time switch, with improvements along the way.  The early versions were not smart enough to vary the length of time of assist based on coolant temp, later versions do.  There is a great writeup in the "starting aid" in the tech manual.

g

[hands_aus]

G,
When I first bought my car the cold start relays were all not working because of dirty internal contacts.
After I cleaned the relays and filed the contacts, the car was easier to start but still not working properly so I added the hidden press button.
Eventually I fitted a one second 'time switch' from a finnie sedan because of the fuel leak-back of my injection pumps' check valves.

The wiring to the time switch is in parallel with the thermo time switch and so they both operate when cold but the thermo time switch holds the CSV open longer than one second.
During a hot start, only the time switch works, just for one second.
It works great hot or cold.
One day when I have the inj pump rebuilt i will be able to remove the non standard (for my 250sl) time switch.

In the mean time I prime the fuel system for about 25 seconds after the car has been sitting for a long time.

Combining the small time switch mod with the ballast resistor by-pass relay, the car starts great.

[enochbell]

Thanks Bob, I will check the relays.  And, BTW, I have the same issue with leak down, which causes the engine to hot-start on just 3 cylinders.  But the others catch after about 10 seconds or so.  Sure wish there was a fix for the faulty check valves but I don't think there is.

The other Greg

[Greg]

Thank you Bob, I like what you are saying.

Greg