300sd starter click
 

this has been a frustrating issue that keeps happening. my selanoid on my starter will only click until the glow plugs turn off. then i can start my car. i put in new positive and negative cables ground strap and new bosch starter. it will do it cold or hot. any thoughts? battery is testing at 14v at terminals while idling and its 12.64 after sitting overnight... if i put my jump box with 1200cca on it the car starts right away.

bad battery, just because it has voltage doesn't mean it has the cranking amps left in it, what does it do with all the lights on? What does it drop to when glowing? Should be no less than 10-10.5V steady under glow. The 617 has a massive 2.2kw starter that needs a LOT of juice to turn over.

Try jumping the terminals in the junction box down near the alternator (if it's a 126) and see if the starter works. If it does, you may have poor connections in the ignition circuit.

About a week or so ago it happend to Me; I turned out My Battery was shot.

My Battery showed 12.5 Volts. With the Volt Meter connected to the Battery I had My Wife attempt to crank the Engine. I got the Solenoid Click and My Battery Voltage dove down to 2 Volts.
So that is an easy test.

I figured it was unlikely that the Voltage drop was due to a short because that sort of load on a short circuit is going to burn something.

If you Solenoid clicks and your Voltage remains the same or close you have another issue somewhere.

I installed an extra Battery I had and have had no more issues.

The definative test would be to charge the Battery and have it load tested.

The solenoid clicking but voltage staying the same can mean worn brushes in the starter or a dead spot in the windings of the starter motor. Had that happen recently on my 190...

i have no click or connection with starter jumping the 1 and 3 terminals.the glow plug relay clicks but not solenoid. i just replaced the wire going from the solenoid to ignition relay where i found a burn in the wire and now i get no clicks and nothing. i used ten gauge wire for the ignition relay to solenoid wire was that too thick. also the first time i tried to connect the battery cable i didnt realize that my red wire was touching the heat shield and it sparked. i have since moved the wire. thought i might also add that i get 12.5 volts at all positive wires. my ignition relay mounted on the fender isnt clicking when the key is turned... could i have blown the relay when i sparked the terminal?

Can you still jump start the car using your 1200cca jump box (connected at the battery terminals)? If so, you need a new battery, the voltage doesn't mean you have enough amperage.

I have a battery dated 1/2012 sitting at home, it won't even get up to 12 volts anymore, it was in my 300sd when I bought it a few months ago. The car needed a voltage regulator and had been boiling that battery away (at over 15 volts) ever since it was installed. I found a guy on craigslist with a 300sd parts car and swapped the entire alternator for a newer looking one. The newer voltage regulators look different, kinda flush mounted except for a round part in the middle. My old voltage regulator was a blocky black or brown thing that reminded me of other 1980's solid state electronics.

After verifying that the charging voltages were more healthy, I went and bought that huge autozone battery with the 150 minute reserve capacity. No cranking issues anymore, makes me very happy.

EDIT: Anybody have a washer fluid pump they want to send me? All that battery acid dissolved my old one. :( I really need to get out to the pick and pull.

Won't even click with the jumper box on. I forgot to add that the battery starter alternator and all wires and grounds and battery cables have been replaced as we'll as a new ignition switch within the last four months.

I am curious. On the W123s there is no Starter Relay.

Is that a stock part on an 81 300SD?

Is it possible that the Neutral Saftey Switch Burned?

What happens when you jump directly from the Battery to the Terminal the Arrow Points to in the Picture.

nothing at all... there is no click from starter or solenoid

It is possible i did hear a pop spark sounds down by the starter when the cable touched. i saw a small burn mark on the heat shield. i tested all the fuses and tested voltage to the ignition and everything checked out.... i took out my starter and have one on order for tomorrow. i hope that solves it.

If you went direct from the + battery Terminal to the terminal in the picture in Post #10 with another Wire bypassing the normal Curcuit possible problems.

Battery Dead
Starter not grounded
Solenoid Bad or somehow jammed but not enough that it has gone all the way back.

Refer to the Pic in this Post.
Use a Jumper Cable or the Positive Battery Cable and jumper to the Terminal Shown in the Picture. When you apply Positive Voltage there the Starter should spin.
If it does not spin:
The Battery is Dead
The Cable has an open circuit
The Starter is not grounded
Some issue with the Starter itself

yeah i put my 1200cca jumper on it directly as you have shown and it would do nothing. i had it grounded to chassis and even when i got the starter out the bench test would not even make a click sound.

Bad News!