Engine suddenly cuts, then starts again with compression or lots of starter

[Jkalplus1]

Hello,

After a rebuild of the head, I took my 64 230SL home on a 475km journey, runs strong, no pinging, even when under load (i.e.: going up a steep hill, under 3000RPM, gas pedal to the floor).  Life is really good!  Love it, love it, love it!

Timing is set at 37 degrees, gasoline used is 94 Octane (AKI), torque pull feels even across all RPM and strong, top end power is felt all the time.  I may be wrong, but I have a hard time picturing this engine sounding and pulling any better.  I have stock ignition installed, all the parts (rotor, points, spark plugs, spark plug wires etc) are new with less than 100km on a complete rebuild.

I take the car on little drives, the warm idle is nice and even, the RPM needle just at the 1000 mark, but the “sound” tells me I don’t want it to idle slower…unless I am missing something.   Anyway, this is the background.  Since taking the car home, I put on another 300km of a mix of city and highway, no issues.

The day before yesterday:  It was a hot day and I was commuting back home.  The engine just stalled at a stop light.  I was able to restart it (lots of starter time), and resume my commute.  Then it cut while driving, when in gear.  I left it in gear, kept the foot on the gas, compression was slowing the car progressively until the engine caught again.  I experienced this problem again maybe 5 or 6 times more on the 40km return trip.  I was always able to restart it, but it leads me to think I have a “trouble”.  It will pull beautifully in a nice acceleration, or steady RPM cruising, and then just cut…compression eventually gets it started again.

Could it be a factor of the car spending a lot of time idling in hot weather on this particular day?  My temp gauge was reading fine (it is new).  This idling in stopped traffic is the only “different” thing I’ve been doing.  I have not driven the car since.

Any insight and assistance in troubleshooting this much appreciated.  I have not been able to find an existing thread in the archives or an article on the tech section to figure this one out.

Jerome

[Cees Klumper]

Jerome - I would start with the ignition system; possible shorts inside the distributor or elsewhere in the circuit. Also the ignition switch inside the cabin (where the key goes) could be acting up. Others please come in with other suggestions.

[paults1]

I had the same experience 2 years ago. Sometimes the engine would die when running on rough roads or over bumps and sometimes on sharp turns on the road.  I later discovered that by jiggling the key while running the engine would cut out.  The ignition switch was the problem.  I replaced the switch. New switch less than $100.  Lots of work to do this. Tech. Manual has the procedure.
Regards, Paul, '63 230SL

[kayemoxon]

Are you able to say that your fuel tank is not carrying any debris from internal corrosion. Have you checked the fuel filters? In addition to the engine mounted fuel filter there is the fuel pump filter (inside fuel line connection on the pump) and the tank filter (inside above drain plug)
Your problem sounds typical of fuel delivery issues. Many threads relating to this subject in the forum.
Regards
Kaye (Cardiff UK)

[Jkalplus1]

Thanks gents,

I thought about the usual fuel supply suspects corrosion, etc, but this car just underwent a frame-off rotisserie restoration, and complete mechanical overhaul.  So, refurbished gas tank, new lines, filters, FI pump rebuilt by Hans, the whole bit, etc.  On the ignition side, new switch, wire harnesses, rebuilt distributor, new points, rotor, cap, plugs, plug wires, etc.

I think I found the problem:  removing the distributor cap there is a wire that runs a little close to the housing.  When the screw on the outside is tightened, it may have brought the wire too close to the housing, thus allowing it to short from time to time.  I moved the wire a little closer to the center.

The trouble has not happened again.  It runs like a dream. 

Thanks to all for your help gents!

Now...I have this Pertronix (1864A) in the garage...my father (it was his toy but he died shortly after completing the resto) was contemplating going Pertronix, but I am really debating messing with something that works just fine.  I am thinking it might make this kind of trouble less likely to happen again in the future though...