230SL Rejuvenated

[ctaylor738]

I recently took delivery of an early 4-speed 230SL, #133.  Thanks to Cees Clumper for re-posting the Craigslist ad that led to the purchase.

When it arrived, the car ran OK but didn't have the pep it should have.  It also had no shifter bushings which made it a challenge to drive and diagnose at the same time.  So I replaced the bushings and did some troubleshooting. I did it step-by-step with a road test after each change.

Car has a PerTronix Ignitor.

1. Fixed the way over-advanced timing, dialed back to 2 degrees BTDC.  Car would barely idle, so added some air and fuel to get 4.5% CO and a good 800 rpm idle. Test drive, more power but stumbling at above 3000 under load. 

2. Discover 5k ohm coil wire, AND 5k plug wires AND resistor plugs, in addition to 5K in the rotor.  Poor thing.  Replace plugs with non-resistor and rig temporary setup with some 1k wires I had laying around.  Borrow coil wire from the Ponton.  Test drive shows improved power and miss moves up to 4500 or so rpm. 

3. Replace the brown coil with an old blue coil.  Now pulls very strongly as far as you want to take it. 

I think I can get some more out of it if I fatten up the mixture with a couple of clicks on the rack as the plugs are showing a very lean burn.

I hope helps with diagnosing running problems: Pertronix, 1K wires, non-resistor plugs (Bosch WDC-7 or NGK BP5ES) and a Bosch blue coil.  Same for a 123 distributor, but Bosch red coil.

Cheers,

CT

[Iconic]

Congrats Chuck on the "new" 230 !!
I guess that Craiglist add was not a scam.

[Leester]

Congratulations Chuck on the new acquisition.  Sounds like lots of sorting which will indeed help others with diagnosing their issues.  Some day we will all be getting together again and look forward to seeing you and the car.  Lee

[Shvegel]

If you have not replaced the distributor cap I would also do that.  One of the reasons our cars do not like a lot or resistance particularly with the increased firing voltage with electronic ignition is the cap diameter is quite small which increases the chance of cross fire between the terminals on the cap.  I am guessing Mercedes had issues once they went to electronic ignition since they they a couple of band aids at it by adding a rain hat to the distributor then to the coil and finally increased the size of the distributor in later models after the M130. 

Also look for and signs of burning along the rotor arm.  I have not seen it with Pertronix but with MSD systems I have seen the increased amperage across the rotor burn the internal resistance out in the rotor.  The usual fix is to solder a wire across the resistance in the rotor.  I will see if I can find a link so you know what to look for.

[perry113]

I just put a 123 distributor in my 1965 230SL and it is one of the best things I ever did. Also make sure your vaccum line and port on the intake is working.
The best money you can buy to take a multitude of issues off the table.

[Benz Dr.]

I recently took delivery of an early 4-speed 230SL, #133.  Thanks to Cees Clumper for re-posting the Craigslist ad that led to the purchase.

When it arrived, the car ran OK but didn't have the pep it should have.  It also had no shifter bushings which made it a challenge to drive and diagnose at the same time.  So I replaced the bushings and did some troubleshooting. I did it step-by-step with a road test after each change.

Car has a PerTronix Ignitor.

1. Fixed the way over-advanced timing, dialed back to 2 degrees BTDC.  Car would barely idle, so added some air and fuel to get 4.5% CO and a good 800 rpm idle. Test drive, more power but stumbling at above 3000 under load. 

2. Discover 5k ohm coil wire, AND 5k plug wires AND resistor plugs, in addition to 5K in the rotor.  Poor thing.  Replace plugs with non-resistor and rig temporary setup with some 1k wires I had laying around.  Borrow coil wire from the Ponton.  Test drive shows improved power and miss moves up to 4500 or so rpm. 

3. Replace the brown coil with an old blue coil.  Now pulls very strongly as far as you want to take it. 

I think I can get some more out of it if I fatten up the mixture with a couple of clicks on the rack as the plugs are showing a very lean burn.

I hope this helps with diagnosing running problems: Pertronix, 1K wires, non-resistor plugs (Bosch WDC-7 or NGK BP5ES), and a Bosch blue coil.  Same for a 123 distributor, but Bosch red coil.

Cheers,

CT

I would dial it up to 8 degrees BTDC. W9DC  is equivalent to BP5ES. The blue coil is supposed to be for CD ignition cars so I would go with the red one.

[ctaylor738]

Well, the latest wrinkle.  I ordered a new blue coil and installed it.  The engine went back to missing at 4K rpm or so.  I measured the resistance of the new coil, and it was on-spec at 3.8 ohms.  The old blue coil has .8 ohms. 

Carl at RetroRockets advised me that running with a coil with that low resistance can fry the Pertronix, and advised measuring the resistance between the distributor plate and battery negative.  Should be less than 2 ohms.  That's today's task.

Thanks for all the suggestions.

The car has an 051 distributor (vacuum retard) and a later throttle body.  As part of my long-term goal of getting the car back to original my plan is to find a 049 distributor (vacuum advance) and a corresponding throttle body.  But I would like to figure out what is going on with the existing set-up.

Stay safe,

CAT