Bad ignition switch? Bad wiring? Bad ground? Starter solenoid issues! - PeachParts Mercedes-Benz Forum

gastropodus · #1 08-13-2014, 04:01 PM

Hi, here is the situation: I began to experience problems with my starter in the 240D over the last few months in which I would turn the key, and just get a single click. I had the battery checked out, and it was putting out 1000 amps no problem, so I assumed it was the starter. I took the starter in for rebuild, and then put it back in the car. The first few times I started the car after the rebuild it was like heaven: that starter engaged every single time, it was spinning fast, I hardly needed a glow.

Now, the old problem is rearing its ugly head again... turn the key and I get click. If I bang the starter with a hammer it engages on the next key turn. If I reduce my glow time to a second or two it usually spins, but then it takes more turns of the starter to get ignition. I had the battery checked again; still putting out 1000 amps. Is it possible that the new solenoid is just bad? The rebuilder says that I might have issues with the ignition switch or the wiring, and the solenoid isn't getting enough current. He said it might need up to 30 amps to engage the solenoid - anybody know if that is true? Seems high to me. I can't imagine that the ignition switch is designed to pass 30 amps, but I could be wrong. The rebuilder says that a common solution is to put in a relay: the ignition switch energizes the relay, the relay sends many amps to the solenoid, the solenoid contacts send hundreds of amps to the starter motor.

So, here's a question: how many volts should I see across a W123 starter solenoid when I turn the key to the start position? Anyone know how many amps it takes to kick the solenoid into the engaged position? Should maybe just order a good German solenoid from the dealer, and say the heck with the rebuild place?

Thanks,

Kurt

Diesel911 · #2 08-13-2014, 07:20 PM

When My Starter Cranks 84 300D turbo Diesel it draws about 150 amps (Measured with an Automotive Inductive Ampmeter) total. I don't think there is any reason for yours to go even that High.

Also you seem to be missing a step in the Trouble Shooting wich would be to connect a Remote Starter Switch (or Jumper Wire the Solenoild) to see if the Starter operates normally. Doing that bypasses the Ingnition Switch.
If your Starter works all of the time like that you know it is not the Starter.

Put your Voltmeter on the Battery and have someone Crank the Starter and see what the Voltage Drops to.
Even using the Glow Plugs it sould stay around 11.5-11 Volts and during cranking (note that during Cranking your Glow Plugs are connected).

If it drops below that Voltage re-charge the Battery and take it and have a Load Test done on the Battery. When the do the Load Test they have an adjustable Resistor that the use to somewhat take the place of the Starter and the Battery is supposed to hold X amount of Voltage put out X Amps according to what the Batter was designed to do on the Lable (Cold Cranking Amps or Amphours).
The only flaw in the above test is if you bought a Batter with insufficient capacity to begin with. They do the test based on what the Battery itself was designed to put out not based on what car you have.

If the Battery is OK then you need to look elseware for the problem.

See the pic in post #2.
Help I'm Stranded!

Concerning rebuilders. It is possible for rebuilt parts to have problems evenw when they are rebuilt with good components.
But I noticed when I was looking at Starter Parts there is Generic Starter Solenoids that were around $12 and then there was the Real Bosch Solenoids that were at least 4 times that cost.

If the Rebuilder used a generic Starter Solenoid that could also be the issue.

mtgoz · #3 08-13-2014, 08:02 PM

I just went through a similar issue. The problem was intermittent. I would have to jump the solenoid to bypass the switch. I thought it was the ignition switch attached to the ignition lock. I replaced the switch and the issue appeared again. This time I replaced the complete ignition lock which includes the switch. I have not had an issue since.

Phillytwotank · #4 08-13-2014, 09:27 PM

What exactly did they replace when the starter was rebuilt. Did you replace the battery to starter cable?

funola · #5 08-13-2014, 10:08 PM

The starter solenoid draws 8 amps max. Next time its happens jumper the starter solenoid to battery +. If it still clicks, could be a bad ground strap connection. If it starts, could be bad ignition switch neutral safety switch or wiring.

gastropodus · #6 08-14-2014, 12:42 AM

OK, thanks for all the replies. I will check this stuff out over the next few days and report back. Just for the record, I replaced everything having to do with the ignition switch about a year and a half ago: new lock, new electrical part, new housing even. I haven't replaced any wiring anywhere at all, though. And somehow I doubt that they put a real Bosch solenoid in the rebuild, given that the rebuild cost only $115.

That's good news that the solenoid draws less than ten amps: it means I should be able to use a standard volt-ohm-ammeter to measure what current and voltage is being presented to the solenoid.

If it comes down to getting a Bosch solenoid, any ideas on where to go for one? Dealer? The Peach Parts catalog did not seem to list solenoids as a separate, orderable part.

Thanks,

Kurt

gastropodus · #7 08-14-2014, 12:44 AM

Quote:

Originally Posted by Phillytwotank

What exactly did they replace when the starter was rebuilt. Did you replace the battery to starter cable?

Well, it has a bright, shiny new solenoid on it. I think that they turned down some rotor stuff inside, and replaced some brushes. I did the wrenching and brought the starter assembly to them, so there was no chance of them doing anything with the wiring.

Kurt

gastropodus · #8 08-24-2014, 12:46 AM

Update: I cleaned the battery ground strap, and still had the problem (the problem being that the 240D usually starts when dead cold, but seldom spins after the engine has warmed up and been turned off).

I borrowed a jumper wire with gator clips on it from work. Today after I had driven the car to the store nothing would convince the starter to turn over. Just click each time. So I turned the key to start (got nothing), let it go back to run position so as to turn off the glow relay, attached one end of the gator clip wire to the starter solenoid, and then touched the other end to positive battery terminal. The starter, of course, zoomed to life and the engine started up.

So, at this point it does seem to be either ignition switch or wiring. There is a small chance that there is still some problem with the solenoid, but since I've seen the problem with the starter circuit both pre- and post-rebuild on two different solenoids the switch or wiring are more likely. As I recall the ignition switch I put in was not from the dealer, it was a third-party unit sourced through the local import parts house.

Now I've got a couple choices. I invite your comment on them.

1. Order an OEM electrical switch from the dealer, disassemble the ignition switch and replace it.

or

2. Just order a $25 relay kit from Peach Parts. Install it so that ignition switch turns on the relay, and the relay closes the circuit for the solenoid.

or

3. Do more debugging on the wiring: Try and find an upstream place on the wiring closer to the switch, and jumper from there to the solenoid to see if that fixes it. Does the solenoid activation current go through one of the fuses in the fuse box? Could this all be due to a bad fuse?

Thanks for your advice.

Kurt

Diesel911 · #9 08-24-2014, 11:03 AM

Quote:

Originally Posted by gastropodus

Update: I cleaned the battery ground strap, and still had the problem (the problem being that the 240D usually starts when dead cold, but seldom spins after the engine has warmed up and been turned off).

I borrowed a jumper wire with gator clips on it from work. Today after I had driven the car to the store nothing would convince the starter to turn over. Just click each time. So I turned the key to start (got nothing), let it go back to run position so as to turn off the glow relay, attached one end of the gator clip wire to the starter solenoid, and then touched the other end to positive battery terminal. The starter, of course, zoomed to life and the engine started up.

So, at this point it does seem to be either ignition switch or wiring. There is a small chance that there is still some problem with the solenoid, but since I've seen the problem with the starter circuit both pre- and post-rebuild on two different solenoids the switch or wiring are more likely. As I recall the ignition switch I put in was not from the dealer, it was a third-party unit sourced through the local import parts house.

Now I've got a couple choices. I invite your comment on them.

1. Order an OEM electrical switch from the dealer, disassemble the ignition switch and replace it.

or

2. Just order a $25 relay kit from Peach Parts. Install it so that ignition switch turns on the relay, and the relay closes the circuit for the solenoid.

or

3. Do more debugging on the wiring: Try and find an upstream place on the wiring closer to the switch, and jumper from there to the solenoid to see if that fixes it. Does the solenoid activation current go through one of the fuses in the fuse box? Could this all be due to a bad fuse?

Thanks for your advice.

Kurt

The Fuse Chart attached to the Lid of your Fuse Box will tell you what Fuses go where.

There is a long thread that has somplace to view the Fuse Box Chart if you do not have one somewhere in one of the below Links.
Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82
http://www.peachparts.com/Wikka/DoItYourSelf

There is a Chassis to Bell Housing Ground Strap on the Left side under the Car about where your Feet would when you sit in the Seat.

funola · #10 08-24-2014, 11:13 AM

Have you removed the wires at the starter motor, clean with a wire brush and re-install? If not, that is what I'd recommended next. Be sure to disconnect battery first. Ps, do not over torque the nuts, it is an electrical connection, not starter mounting hardware. Over torque will crack the plastic on the solenoid.

dieselbenz1 · #11 09-26-2014, 07:47 AM

Sure sounds like a bad solenoid after that experience.

cooljjay · #12 09-26-2014, 10:16 PM

I would replace the starter to battery cable, these are known to corrode inside the sheath....I would replace the ground cable and the positive cable with 2 gauge cables, it is a great mod/upgrade to do...

gastropodus · #13 10-24-2014, 01:12 AM

OK, so this is ancient thread, and I really should have figured this out by now. I finally broke down and bought a Craftsman non-contact DC current meter (the kind with the doughnut pincers). I have measurements!

So, when the key is turned to the start position with the meter installed around the solenoid wire it reads 33 amps while (non-)cranking, and that holds steady for several seconds while the starter, of course, is sitting there dead. On an earlier occasion I managed to get a reading on a successful start, and it appeared that the solenoid wire was reading about 10 amps for the few seconds that the starter was engaged and turning. I think what I'm seeing there is the two different coil impedances: there is a high current coil in the solenoid, and a low current coil.

There is definitely a solid click that I sense coming from the starter/solenoid pair while I'm under the hood with the meter. I put the meter in voltage mode, and measured the voltage on the output terminal of the solenoid (the thick wire that goes into the starter brushes). While the key is turned to start, and after the click, this voltage reads about 0.7 volts. This is with the black lead of the meter on the battery negative post, and the red lead on that solenoid output nut.

Do these measurements point toward brushes that are stuck in some way? It certainly seems like the 33 amps ought to be enough to activate a solenoid and slam it against the contacts (the click) to send juice to the starter motor proper.

Thanks,

Kurt

funola · #14 10-24-2014, 11:22 AM

Quote:

Originally Posted by gastropodus

OK, so this is ancient thread, and I really should have figured this out by now. I finally broke down and bought a Craftsman non-contact DC current meter (the kind with the doughnut pincers). I have measurements!

So, when the key is turned to the start position with the meter installed around the solenoid wire it reads 33 amps while (non-)cranking, and that holds steady for several seconds while the starter, of course, is sitting there dead. On an earlier occasion I managed to get a reading on a successful start, and it appeared that the solenoid wire was reading about 10 amps for the few seconds that the starter was engaged and turning. I think what I'm seeing there is the two different coil impedances: there is a high current coil in the solenoid, and a low current coil.

There is definitely a solid click that I sense coming from the starter/solenoid pair while I'm under the hood with the meter. I put the meter in voltage mode, and measured the voltage on the output terminal of the solenoid (the thick wire that goes into the starter brushes). While the key is turned to start, and after the click, this voltage reads about 0.7 volts. This is with the black lead of the meter on the battery negative post, and the red lead on that solenoid output nut.

Do these measurements point toward brushes that are stuck in some way? It certainly seems like the 33 amps ought to be enough to activate a solenoid and slam it against the contacts (the click) to send juice to the starter motor proper.

Thanks,

Kurt

33 amp draw for the solenoid is too much, should be around 8 amps. There's a fault somewhere in your car or your meter.

0.7v is almost a dead short. Again, a fault some where in your car or your meter.

gastropodus · #15 10-27-2014, 12:58 AM

No, I'm very sure of my measurements.

I finally took the car in to the auto electric shop that rebuilt the starter. I was loathe to do that at first because they were snobby about "we'll look at it, but if we determine the problem is something else on your car we're going to charge you for the diagnosis." However, I had come to my own conclusion, and was confident that they would come to the same one. And they did: bad rebuild. The mechanic wasn't 100% sure, but he thought it was the solenoid. I, on the other hand, am pretty confident that it IS the solenoid, confident enough to go and buy a new $55 Bosch solenoid.

Here is why I think it is the solenoid. There are two coils in the solenoid, the pull-in coil and the hold coil. The manager at the auto electric place confirmed that the pull-in current is about 30 amps. The way it works is like this: when you initially turn the key to Start, the circuit goes

Battery -> Keyswitch -> Solenoid_screw_terminal -> Pull-In_Winding* -> Starter_Motor_Supply_Terminal -> Starter_Motor_Windings -> Ground

I put an asterisk above because current also flows through the hold winding directly to ground, but that current is less.

So, what happens when the solenoid operates properly is that the pull-in winding slams the bar across the contacts inside the solenoid to send battery voltage (and many amps) to the starter motor supply terminal. This raises the voltage at bottom end of the pull-in winding from near ground (which is what it is before any solenoid movement, because of the low impedance of the starter windings) to battery voltage. Now the pull-in coil has battery voltage on both ends, and current ceases to flow through it, leaving only the hold coil current, which is the afore-mentioned 8-10 amps.

The web page that led me to this understanding is here:

Bosch Starter Solenoid Rebuild - Inside a Dual Coil, Pull-in and Hold-In Starter Solenoid

So, how does this fit with my symptoms? Well, since I see in 33 amp pull-in current all the time, and the starter motor does not energize, the bridging bar is not reaching or not properly contacting the contacts that bridge the battery input terminal on the solenoid to the starter motor supply terminal. Ergo, bad solenoid. Or they replaced the solenoid winding/housing, and re-used the old plunger (and it doesn't match well).

So, now we get to my question. The starter is back out of the car, sitting on the dining room table. The new Bosch solenoid is sitting next to it. How much of the starter do I have to disassemble to be able to put both the new Bosch solenoid and the plunger that came with it onto the starter? I've seen the writeup Stretch did on disassembling the whole starter; what I could not tell from his posting was whether it was possible to replace the plunger without pulling the whole casing to get access to the engaging fork. I'm thinking that the end of the engaging fork goes in the slot of the plunger shaft, with the spring there to keep it against one end of the slot. I could be wrong, but I don't think I replace that plunger without some disassembly of the electric motor portion of the assembly.

Thanks for your help.

Kurt

Edit: I'm sure someone will suggest to take back to the place that did the rebuild... I may still do that, but if it is relatively straightforward to replace the entire solenoid myself I would just as soon avoid those clowns.