Diagnosing starting problem 1980 300D

Last weekend I installed a remanufactured starter motor. The engine turned over fine at first, but on roughly the 6th start-up I heard a loud spinning sound coming from the starter motor that didn't stop once the engine was idling. Also, it didn't stop when I killed the motor and took my key out of the ignition. I had to disconnect the battery to get it to stop. After waiting a few minutes, I reconnected the battery, and started the car successfully on 5 or 6 occasions after that. Now my car won't start at all. Kent, I watched your video (big help), and connected the two posts on the starter motor as you instructed. It sparked and clicked, but the engine didn't turn over. Note that I don't hear this clicking sound when I've attempted to start the car normally with the key (I get nothing after the glow-plug buzzer stops). So, I guess I'm wondering what I should do next. Does it sound like a faulty starter, a faulty ignition switch, or both? Thanks for your help!

Collin

Forums

Diesel Engine Specific Aid

Hard to say without further tests.

.
A stuck starter problem could have damaged your ignition switch. Get the starter working first. Remove the factory small wire at the starter removing the small screw. Using a long wire apply 12 volts from the battery to the small screw connection terminal at the starter. Make sure your battery is tested and properly grounded (this is important even if you think you battery is ok). If the starter wont turn over now then there is something wrong with starter.

Next connect a 12 volt test light to the small factory wire you disconnected from the starter. Turn the key to start position. If the test light does not light up you have something wrong with your ignition switch or the neutral safety switch.

Thanks!

Thanks, Kent. I should be able to give that a try this weekend. Your website is the best.

Starting problem 1979 300SD

Hey Kent,
My son's turbo diesel starter "burnt out", coinciding with A/C use.
The solenoid (small factory wire) was receiving 12V (test light) with the ignition in the glow plug/run position, as well as in the start position.
Replaced the 8 pin ignition switch under the instrument cluster. Same condition.
A while back we replaced the neutral safety switch on the AT (back-up lights were inoperative. The plastic switch "arm" lever cams were worn down). Ruled that out.
Next we replaced all 3 relays located behind the vertical panel next to the parking brake pedal. The solenoid stopped getting 12V in the glow plug/run position.
Figured the bad relay was the top one (36..disconnection A/C (supplementary fan) from ignition switchover CN 8). I'll test it for stuck contacts 30 to 87/87a.
Replaced the starter. Used 4 1/2" drive wobble extensions (2') to get those 2 nasty mount bolts (10mm hex) out. Thanks for the great tips on that. Everything works now. We may rebuild the burnt starter with brushes, bushings, and possibly solenoid. Keep up the good work, man.