Help! Weird Starter Issue!
 

1982 300sd . . . . so, the other day, I start the car normally and the starter remains engaged with engine running! I freak, and turn off engine but engine will not shut off not even with emergency vac switch so I rev car slightly and clear starter and am then able to shut off car normally car starts again, same issue, rev and clear starter - starter btw, is a brand new (one month) Bosch reman, not a O'Reilly special . . . I start car again, all normal . . . and drive it where it leaves me stranded the next morning where we have it towed to my indie who cranks car via remote starter switch. By now, because car remained running when I turned switch off I figure (and my indie) bad ignition switch (switch was not springing back) which makes sense so we pull tumbler, etc and change ignition switch - problem persists, no change but no cranking possible. I crank car by jumping starter and it fires immediately this morning. Any ideas? Very bizarre problem and need to drive to Seattle with car tomorrow! Any thing I overlooked? Ever happen to you? When I crank car via jumping the starter, everything perfect, solenoid responds normally and retracts when engine fires - weird!

did your indie replace the entire switch assembly or just the tumbler? that back electrical part can cause problems

replace the bendix.

Is the idle RPM really low? Revving it briefly after starting always clear it up?

hmm, disregard that, I read your post a second time. strange.

Thanks as post said, ignition switch was changed and tumbler several years ago -

Bendix fine, springs back perfectly when jumped at the starter in other words, starter engages and when engine fires, it does not remain engaged - thanks for your help!

Don't use the key on your trip to Seattle. Just start it from the junction box under the hood. Or if you don't want to pop the hood every time to start it run a remote start switch out thru the cowl where it can remain or into the passenger compartment.

Had a similar problem years ago on a 240D, our problem IIRC correctly was the key itself binding just enough to overcome the return tension of the ignition switch. Have you been using a different key? Do you have a different one to try? Be careful and certain to correct this problem, ours stuck so badly that it melted the insulation on the battery cable, this obviously could have been a fire.

Thats an idea! Let's see - one lead to positive and the other at the junction box -which wire? Thanks Kerry!

Terminals 1 and 3 in the junction box will do it.

Great, thanks!

And the verdict? Bad neutral safety switch. Car started working normally after I jumped the starter yesterday and then the next morning, same issue again. I wiggled the gear selector in Neutral this morning (again) just to double check and low and behold, it cranked which confirmed wonky NSS - even the reverse light came on in reverse so these switches can seem like they are acting normally but not always - in my case, I had both a bad ignition switch and a failing NSS at the same time - hope this helps someone else with a car acting similar -

I have no clear idea as to how a failing NSS would cause the starter to stay engaged. Does anyone else?

Kerry, as I mentioned, I had a failing ignition switch and NSS, both at the same time. My ignition switch did not spring back which kept the starter engaged . . . and then NSS failed -two events happening at the same time which made diagnosis a pita -