Starter Issues

[Harry]

As part of my 230SL rebuild, I replaced the original starter (or at least old starter) with a new Bosch.  The Bosch is smaller but was the one assigned to this model and bolted right up.  I have finally reached the point of turning the new engine over today to check oil pressure but the new starter wouldn't participate.

It will click one time with each turn of the key, but it does no more.  I tried in Park and Neutral with the same results.  I considered that I had a ground problem so I grounded the battery with jumper cables to a bolt on the frame to be sure that I had a solid ground.  Same results.

Any ideas before I pull the starter?

Thanks,
Harry

[ja17]

Start with the basics. Is the battery dead?

[Harry]

No - new battery.  I think I'll have top pull the starter and check it on the bench, unless I am missing something else.  Any issues reported with the new Bosch starters?

(Thanks Joe.)

[Harry]

Interesting.  I see that I get the same symptoms regardless of the position of the shifter (automatic).  That is, I get only a “clicking sound” (only one) with each turn of the key.

If this interlock is working, should I get any response if not in Park or Neutral?

[Charles 230SL]

Harry, unless you're already replaced it, the positive battery cable could be your problem. I had to replace mine a couple of years ago: https://www.sl113.org/forums/index.php?topic=27245.msg195431#msg195431. Mine had corrosion on the inside strands but it looked fine on the outside.

Your ignition/solenoid wire could also be the culprit. It's labeled 2,5 vi (2,5mm2 cable diameter, violet) on the wiring diagram. The one on my 230SL was in really bad shape from all the heat off the exhaust manifold; I replaced it with 12 gauge wire.

be well, Charles

[ja17]

Before removing the starter, touch a 12 volt wire to the small  screw on the starter and the starter should activate.

[Harry]

Rather than touching the 12V wire to the small terminal on the starter, I placed a voltmeter on the connected wire and it gave me 12V when the ignition was switched to the start position.  S, I painfully replaced the new starter with the old starter (miserable job) and it spun the engine right over.

Apparently, either the new starter was defective (not likely) or the wiring to the new Bosch starter is different than it was for the old starter.  The old starter had the big 12V line from the battery and a smaller wire to the large starter terminal, and two smaller wires to the smaller terminal.  That is what I replicated on the new starter with not good results.

Can someone show how the new starter should be connected?  There's a picture in the tech manual of the same new starter but it doesn't show the wiring connections old vs new.

Thanks,
Harry

[Harry]

OK, here is where I may have erred in my ways.  I connected the one smaller and large 12V line from the battery to the big lug on the new starter just as I had on the old one.  But I connected the two smaller ones on the new one to the phillips-head screw marked 15.  It appears that those two should have instead been connected to the threaded connection point below the "15".  Hope I didn't toast a new starter but we'll see.  Ill try it on the bench tomorrow.

The "15" can be connected to the coil?  To where on the coil and why?  (230SL)

Thanks again,
Harry