Trouble-shooting starter issue - 300SDL - PeachParts Mercedes-Benz Forum

cmac2012 · #1 05-03-2017, 05:13 PM

Suddenly wouldn't start today. My battery was at 12.4 - no crank, no clicking, nothing. I'm at my mother's house near Eugene, OR with some tools and one jack stand. Story of my life. Normally I might just throw in a starter but the nearest one is about 2 hours away and I want to leave tomorrow morning. I don't want to run for one if it's the switch at the tranny that is telling my car I'm still in drive.

I trickle charged my batt up to 12.9, no change.

This site had a good write up:

https://**************.com/problems/engine/engine-wont-crank-over-the-starter

Oops, source not allowed. Here was the paragraph in question:

Quote:

2. Check your starter motor by powering it directly. This will bypass the two switches that control the starter circuit and help to determine if your starter it working properly. You will need a long jumper wire either 12 or 14 gauge wire . First check to see if your car has a starter terminal box that you can access. These are either located near the battery or down on the fender well across from the alternator. There will be three wire connections. The smaller of the three is usually the one going to the starter solenoid. You need to connect 12 volts directly to the small wire connection on the starter. This activates the solenoid and engages the starter. With your car in park and the ignition key off, use your jumper wire to connect the positive post on your battery directly to the solenoid itself or the wire terminal we discussed earlier. If the starter will not turn over then you have a starter problem. 5 times out of 10 replacing the solenoid will solve the problem. If the starter only spins over but does not engage the flywheel then the solenoid is most likely the problem. You can remove the starter and take it to an electrical shop for testing. They can let you know if the motor itself is bad or just the solenoid.

Here's the terminal box I found:

I did and zip, nada.

My question, and I should know this by now, am I applying voltage to the correct terminal? I'm using the one at top, the one with the black lead in wire. And yes,that one wire below might need some shoring up on insulation - there's a secondary coating underneath, perhaps I can find some paint on compound. Either that or go with elec. tape though that seems not especially top notch.

cmac2012 · #2 05-03-2017, 05:20 PM

PS:

I checked the wire leading from the terminal that should be for the solenoid, given that the other stuff is showing some age. It looks fine at every point I could see.

jake12tech · #3 05-03-2017, 05:30 PM

If it's an issue with the neutral safety switch, the easiest way to tell is to put it in neutral and try and start. If that doesn't work, hit the hammer with a starter, not like an animal but give it a little whack and see if it starts. Most likely, it's the starter.

BusterBoyBenz · #4 05-03-2017, 05:35 PM

Been a while since I was under the hood of an SDL but are you sure that terminal block has anything to do with the starter? I seem to recall that arrangement of wiring has to do with the alternator wiring. But maybe I'm mis-remembering!

The starter has wiring directly to the Battery's positive terminal from the 10 mm stud on the starter solenoid, and a small control wire going to the solenoid small stud to control the action.

kerry · #5 05-03-2017, 05:50 PM

I second the hammer trip and jumping the starter directly because it could easily be a bad NSS or a poor connection somewhere in the wiring including the ignition switch. I don't now how hard it is to get a jumper cable to the starter on an SDL.
On my daughter's 84 SD the terminal box to be jumped is on the fender directly across from the alternator. I keep a piece of solid copper romex wire with the insulation trimmed off the ends just for this jumping purpose. The 123's and 126's have a bad reputation of getting poor connections in the wiring which stops the starter from working.

Once you get it started, don't shut if off, drive home without turning off the engine.

cmac2012 · #6 05-03-2017, 06:02 PM

Good points, and I did try to start it in neutral also with no luck of course.

The article says the junction box is near the battery or close to the alternator. This one is right next to that batt with a large wire leading from the pos terminal right to it, smaller than the starter cable of course.

*BREAKING NEWS*

We interrupt this post to report that I have heard about the 'rap the solenoid' tip and have done it many times with no luck. So I hadn't even tried it. This time it worked. Hallelujah, sweet Jesus, etc.

Thank you Jake for prompting me to try the easy stuff first. I used a semi hefty catspaw that was lying about and it done the trick. I'm wondering if this means I should think about a new starter soon. Before this quick fix my options for embarking for home in about 16 hours were driving to Medford (2.5 hour drive one way) and going with O'Reilly's ULTIMA brand of reman. NAPA and Autozone had one in Portland only, about the same drive but with mega traffic. Ultima probably good enough but I'd rather shop for a slightly better unit without the long drive.

Let me add that this car has the solenoid in an excellent spot for easily applying a light rap.

Diseasel300 · #7 05-03-2017, 06:02 PM

I've had problems with the NSS and the solenoid causing issues in my SDL. Try shifting through the gears and stop in Neutral, then try starting it again. The terminal block on the wall in an SDL is not the starter terminals either, that's the alternator wiring block.

cmac2012 · #8 05-03-2017, 06:10 PM

Quote:

Originally Posted by kerry

I second the hammer trip and jumping the starter directly because it could easily be a bad NSS or a poor connection somewhere in the wiring including the ignition switch. I don't now how hard it is to get a jumper cable to the starter on an SDL.
On my daughter's 84 SD the terminal box to be jumped is on the fender directly across from the alternator. I keep a piece of solid copper romex wire with the insulation trimmed off the ends just for this jumping purpose. The 123's and 126's have a bad reputation of getting poor connections in the wiring which stops the starter from working.

Once you get it started, don't shut if off, drive home without turning off the engine.

Oops. I already started it and shut it off. Leaving in the AM. I think I'll go top off with diesel now and that way once I start it tomorrow I can leave it on til almost the Bay area. I get about 500 miles on a tank. But I guess you could almost keep it running while tanking up on diesel.

kerry · #9 05-03-2017, 06:32 PM

I've kept mine running while filling with diesel in similar circumstances. I still have the same starter in the TD which caused me to do that. It hasn't acted up in about 5 years.

86-300sdl · #10 05-03-2017, 06:45 PM

You need to clean the circuit ground point at the body of the car.

Yank out the windshield washer fluid tank by disconnecting the three harness connections, and pull straight up.

Then on the fender-well you will see a single large bolt with the battery negative lead & several brown wire connectors held in place by a washer.

They may look clean but they prolly are not grounding well. Sand, scuff, whatever to clean the ground point up, reinstall and enjoy!

Just went through this with my SDL.

cmac2012 · #11 05-03-2017, 06:50 PM

Great advice. Will do. The long time E30 heads (BMW) are big on inspecting and renewing all the ground points.

BusterBoyBenz · #12 05-03-2017, 07:02 PM

Quote:

Originally Posted by cmac2012

"The article says the junction box is near the battery or close to the alternator. This one is right next to that batt with a large wire leading from the pos terminal right to it, smaller than the starter cable of course.".

I suspect Ken's info is most relevant to the earlier 5-cylinder diesel and 6 cylinder gas engine cars which have their starters positioned on the passenger side of the engine.

The terminal you appear to have been energizing has Black/Blue color coded wiring which usually is the alternator excitation wiring related to the alternator dash light indicator "my alternator is not charging" diagnosis.

Good that you got it started, you could get off very inexpensively if you are willing to clean and lube the solenoid. That's often the failure mechanism, with normal operation the solenoid coil is energized, the solenoid both thrusts the starter gear towards the ring gear and closes contacts energizing the starter motor itself at nearly the same time. The failure of the solenoid ram to move prevents the starter motor from energizing/turning and the gear engaging.

Also on the plus side is the starter on the 603 engine is very easy to get to and remove compared to the 617 starters.

HuskyMan · #13 05-04-2017, 09:43 AM

Went through this on the 1984 300DT. Bought and replaced the starter THREE TIMES before finally breaking down and spending the $$$$$$ on genuine a Bosch starter. That was fifteen years ago, the starter still turns the car over EVERY DAY. I believe peachparts sells both reman and new Bosch starters. Yes, they are priced higher than AutoZone junk but think about this: replacing a starter involves quite a bit of your time and labor.

Do it one time, then drive knowing you don't have to worry about it anymore. A year from now, you'll thank me for the advice.

cmac2012 · #14 05-04-2017, 10:01 AM

Quote:

Originally Posted by BusterBoyBenz

I suspect Ken's info is most relevant to the earlier 5-cylinder diesel and 6 cylinder gas engine cars which have their starters positioned on the passenger side of the engine.

The terminal you appear to have been energizing has Black/Blue color coded wiring which usually is the alternator excitation wiring related to the alternator dash light indicator "my alternator is not charging" diagnosis.

Good that you got it started, you could get off very inexpensively if you are willing to clean and lube the solenoid. That's often the failure mechanism, with normal operation the solenoid coil is energized, the solenoid both thrusts the starter gear towards the ring gear and closes contacts energizing the starter motor itself at nearly the same time. The failure of the solenoid ram to move prevents the starter motor from energizing/turning and the gear engaging.

Also on the plus side is the starter on the 603 engine is very easy to get to and remove compared to the 617 starters.

I've never serviced a solenoid. I noticed that the 603 starter is in an accessible spot. I drove my two E30s about 270K and never had to replace a starter, good thing as I heard it's an ordeal.

I can only imagine that one would need to remove it to service the solenoid. When back home I'll have the luxury of relying on my backup car so as to do that. If it's a Bosch, would make sense to lube the solenoid and extend the life.

cmac2012 · #15 05-04-2017, 10:04 AM

Quote:

Originally Posted by HuskyMan

Went through this on the 1984 300DT. Bought and replaced the starter THREE TIMES before finally breaking down and spending the $$$$$$ on genuine a Bosch starter. That was fifteen years ago, the starter still turns the car over EVERY DAY. I believe peachparts sells both reman and new Bosch starters. Yes, they are priced higher than AutoZone junk but think about this: replacing a starter involves quite a bit of your time and labor.

Do it one time, then drive knowing you don't have to worry about it anymore. A year from now, you'll thank me for the advice.

I was not excited about going with the O'Reilly/Autozone re-mans. Getting anything else on short notice was looking tough. I lucked out here. Not home yet though, don't want to get over-confident.