Engine will not turn over after running

[JayJohnson]

Hello
I have a 1968 280sl 4speed Manual.
Engine has been rebuilt in last 5years runs strong with a heavy-duty alternator and new battery. Points wires plugs coil points all replaced.

Recently had the car with mechanic for low temp thermostat 79C installed fixed overheating fine.

I drive at a moderate speed (10+ miles) then shut off the car return then drive again (5-7 miles) again shut off car then drive (5+ miles) then attempt to start car and it will not start just turn over winding slowly. Car will not start with a jump.

Last time reputable mechanic said a portion of distributor was "stuck, had to be replaced" this time "points were foul"

I do not wish to have a third time with this considering the flat bed fees etc.  Any suggestions are highly appreciated thanks.

[jacovdw]

Welcome to the forum!

Have you had the distributor rebuilt before when the engine was rebuilt 5 years ago?

If not, maybe you can consider enlisting the help of another member on the forum, Benz Dr, to have it rebuilt and properly set up.

You can also change the points to an electronic setup. Pertronix and Crane springs to mind.

Use the search function with Pertronix or Crane as the keywords and you will find that quite a lot has been said about these systems before.

I also trust that your spark plugs are the nonresistor type and properly gapped, valve clearances spot on, ignition timing set and your throttle linkages setup properly.

Regards,

[graphic66]

It could be your starter getting heat soaked and loosing resistance. Or just a bad connection from the battery to the starter. I always start by cleaning the battery connections and go from there. Also check your engine ground. Next time jumping the car hook the negative jumper to the engine itself. Bad connection or bad starter is my guess

[JayJohnson]

I will check the connections on the Battery and go from there. I have thought about electronic distributors before (I have a MSD on a 84 CJ7 Jeep) but did not know they made them for this car. I will look into the Pertronix or Crane.

Spark Plugs are setup properly car drives absolutely amazing just does not turn over after being shut off a few times... go figure

How would I isolate the Starter from being heat soaked? Is this due to its age or some other problem? This would happen to most 280sl's right? Will a new starter "fix" this problem? Should the starter be wrapped in heat isolation and reinstalled? OK Thanks

[graphic66]

The starter can just get old and an early sign of failure can be a hot starter turning slowly. Check your connections and go from there. I believe the only way for the distributor to cause this is by the timing being way off.Check your timing to be sure. These cars run perfect with the stock distributor and points.I often wonder how we managed to make a car run before electronic ignition. Kind of like how many want to install a high geared rearend to bring the revs down and out of the powerband these cars were designed tor run in. Imagine trying to get your formula one racer to cruise at 3000 RPM. I love the sound of a perfect running engine at 4000 RPM when they were made to run all day at that speed.

[menesesjesse]

Have you tried to pop start the car?  If the car pop starts easily we can conclude that all is well at the engine and the culprit is probably the old worn starter.  My car would turn over and slow down after it was warm also.  The new starter in it fixed the problem.  You can use a volt meter to check the volyage drop of the battery after it is warm.  Anything under 9 volts is excessive draw.  Oh I would start with cleaning the selenoid connections first since it may be the cheapest remedy.  Good luck.