cranking stopped, quick helps pls!?

[scottmcphee]

Stuck fuel gauge drops to reserve light on as I'm driving down highway, pull over to next fuel station and stalls ten feet short of the pump. Get it filled, and now begins the cranking on my dry dry om603.

I've had to re-prime the IP on this car before (after doing injectors, or whatever) and I know it takes three or four long cranking periods (20 to 30 seconds each) pedal to the floor to re-wet itself and fire up. Each time I think this is killing the starter... but boom fires up and a couple years pass until the next time.

This time was today. I have a clear section of fuel hose near the IP and after several cranking periods air is replaced by bubbles is replaced by fuel and the engine is starting to do its sputter thing, and nearly catch.

I'm thinking ok next one for sure, and turn the key, and nada. No click, no crank, no action. There's still some juice in the battery all the lights work, etc, I know it's getting slower and weaker each bout of cranking but it was not a slow crank of death to zero. Cranking was doing fairly well and was enough to begin sputtering and firing the odd cylinder, and then the next crank session was.... nothing. Not even a click from the starter solenoid.

Did something pop? A fuse, a thermal protection somewhere, did I fry the solenoid? Is there a minimum voltage hard cutoff relay or something that just says "no" if battery is below 11v or something (I haven't tested batt)?
Sudden dead spot on the starter motor.

My next step is to arrange a battery boost from a tow truck or taxi. But if I'm just going to be faced with a "key does nothing" with a healthy battery hooked up... then my plan of action needs to change.

As I search forums, quick helps or advice requested from those with similar car or past circumstances..

HELP!?!?

[scottmcphee]

Tried a boost. No click no action.

Here's what happens with key turn sequence:
- normal lights across the dash come on
- glows come on for their timed period, waiting
- finish turning key to start position
- no click, no action
- when key is in start position, I notice lights across the dash dim as if solenoid is taking power and lights re-brighten when key is released

At this point I think I have a stuck starter solenoid in the engaged position, or a burnt solenoid coil that is shorting and therefore can't engage.

Thoughts?

Anybody know if there's a big fuse or some thermal cutoff between the battery/key/solenoid/starter combo that I should be checking before I get towed to yank the starter out?

THANKS!

[cooljjay]

I think you killed the starter by over heating it. A new starter may handle the cranking, but a old tired 20+ year old stater won't....you may have even killed the battery....on a w123 there Is a primer pump, you pump this to save the starter and pull fuel into the pump and lines.....then a little cranking will pop the car right off....

[scottmcphee]

Even if the starter coils were burnt, wouldn't the solenoid still at least click?

This is not the first starter for this car. I think it's the 3rd. But certainly not the freshest.

As an aside, previous starter the solenoid got stuck in the engaged position (teeth meshed). It was a lack of lube issue. As I drove away I think the starter began acting like a generator. There was a new, fairly low volume, whirring noise that came along with that... and some funky dash lights... I had no idea what was going on... but next start on that one was a no start.

Retro-fitting a squeeze bulb on a om603... not that it matters at this moment, but a curious add for the future.. potential.

Thanks

[scottmcphee]

Originally Posted by Zacharias

You did try putting the shifter in neutral (you didn't mention it)?

All successful cranking and now unsuccessful cranks are being done or tried with shifter in Park.

I think I know where you're coming from.... once I had my parking brake on, and shifter was in nuetral, or drive, I forget, something other than Park, and got no crank. It was puzzled and dreaded the thought until I finally observed I was not in Park, put it there and away we go.

Are you suggesting a possibility that a faulty interlock switch on shifter is preventing juice to the starter circuit??

[scottmcphee]

hey Zacharias where did your post go... that was weird. I quoted it and now gone.

[gatorblue92]

Sounds like the solenoid is fried to me. Is that a replaceable part or do you need to change the whole starter?

[scottmcphee]

Solenoid is separately joinable to the starter.

From my spares, it is possible to replace it and keep the starter. But I'm pretty sure the starter assembly will have to come out to get at this piece and do it properly.

I guess some bench test of solenoid, and continuity check of its coil will determine its fate.

At this point, I'm arranging tow and will diagnose this problem properly in my own garage when it gets there.

I was just feeling out if there was a possible "easy things" to check or do on the spot (fuses, switch, push start, shifter position, overvoltage relay, rapping a wrench on the side the solenoid.. whatever..) to get past having to tow.

[Zacharias]

Originally Posted by scottmcphee

hey Zacharias where did your post go... that was weird. I quoted it and now gone.

I deleted it as I thought I was probably beating a dead horse.

A faulty NSS is always a possibility.

[funola]

Did you try a jumper from batt + to solenoid? If you get a spark but no click, bang on the solenoid with a hammer and try again.

[pmckechnie]

Hit the starter case with a good size hammer, not the solenoid. If it starts, don't shut it off until you have it where a new starter can be installed. This is usually a 1 time fix. The problem could be worn out brushes in the starter. The hammer will make the brushes hit the armature again and allow it to work one more time.

Paul

[funola]

Hitting the starter may work to jar loose the stuck solenoid. Hitting the solenoid is what you want if it is jammed. The solenoid has to pull in before the brushes get power.

[scottmcphee]

Originally Posted by funola

Hitting the starter may work to jar loose the stuck solenoid. Hitting the solenoid is what you want if it is jammed. The solenoid has to pull in before the brushes get power.

I recalled there was some relationship between the solenoid and starter juice.

When you say "pull in" I read this to mean "engages the gear between starter and flywheel." And in this position power can flow through brushes to starter armature.

In other words there's no sense spinning the starter if it's not driving (connected to) the flywheel, and the solenoid is the thing that makes that connection - bendix drive gear.

[funola]

The solenoid in our Bosch starters provides 2 separate functions. It engages the over running clutch and in the same action closes a set of contacts which spins the motor. Technically it is not a Bendix, but an over running clutch. I don't think modern starters are made with Bendix anymore. They are the type which requires a separate heavy duty starter relay.

A hammer is anything that works to rap on the solenoid. A 1/2" breaker bar or an iron pipe works well.

[pmckechnie]

The solenoid has 2 circuits in it to engage it. One PULL-IN and one HOLD. When the switch sends power to the solenoid, both the circuits get the power. The ground for the PULL-IN is through the brushes and armature. A contact inside the starter then puts full battery power to the armature which disables the PULL-IN part of the solenoid and now the HOLD portion holds the solenoid in until the key is released. The HOLD circuit is not strong enough pull the solenoid in and the pull-in draws too much amperage that the starter motor needs to turn the engine over. If the circuit through the brushes and armature is open (brushes worn out) the solenoid will not pull in. The dash lights dim a little because of the HOLD solenoid circuit. You can hit the solenoid if you like, but hit it in the wrong place and you WILL be replacing it. Hit the starter case anywhere and no damage will be done if you use something smaller than a 10 lb sledge.
Believe me, working on NO-START problems in a small shop ( me and 1 or 2 others) for 20+years I did learn a little bit.

Paul