Intermittent Cranking Issue

[model 10]

Do you have a clear handle on what the terminals on the starter are for? If you just start poking around down there without a plan you might not ever figure things out without spending to much dough. So for example; jump power straight to the brushes ( the motor itself). If it does not turn the motor every time then you have motor / brush problems. If you supply power to the switch term and you get action from the solinoid then you have switch problems. If you put power to the switch terminal and you get no action then you have solinoid issues. Do this bunches of time to maybe find an intermittent problem. As for bad ground issues I don't see how you could have them if the starter is bolted to the engine and the engine is grounded
Just think how much better this is than having these problems on a lee shore.

[FlyingCloud1937]

Originally Posted by Guy

As for bad ground issues I don't see how you could have them if the starter is bolted to the engine and the engine is grounded

Lets just take a quick stab at this.

New rebuilt engine, new stater.

Everything freshly painted, then install new stater.

The engine on a boat should not be used as a conductor/bus bar.

A separate ground cable should be taken from the start battery/neg bus bar, to one of the bolts that mounts the starter.

A inside/outside star washer should be used.

I told the original poster how to check for a fault in the ground/pos cables above.

Ships ground(engine/shaft) is not a bus bar.

Anything powered by the start battery/house battery is open circuit unless it returns by a ground cable back to the battery.

Providing a path to earth ground from ships ground does make a circuit!!!!

Unless it from one underwater metal back to another underwater metal that is attached to ships battery. but then we would have stray current corrosion...now wouldn't we.



Lloyd

[gspeak]

I may be way out of whack here amongst such experts. But is this similar to the much recognized problem that I & many others have had with undersized wiring from the starter switch to the starter on Yanmars in production boats. The symptoms sound very similar.

This problem is easily solved with wiring a relay in at the starter.

Apologies if this has already been suggested.

Dave

[sanibel sailor]

It may be fixed, these intermittent problems are lovely because it may take awhile to be confident in it.

What was the final fix? Bad ground...as suggested in many posts.

While high resistance connections are cumulative, and I cleaned them all, I think the real culprit was one corroded/dirty cable end at the Link Monitor shunt where all the negs combine.

[sanibel sailor]

Originally Posted by gspeak

I may be way out of whack here amongst such experts. But is this similar to the much recognized problem that I & many others have had with undersized wiring from the starter switch to the starter on Yanmars in production boats. The symptoms sound very similar.

This problem is easily solved with wiring a relay in at the starter.

Apologies if this has already been suggested.

Dave

When I jumped a wire across the starter terminals, it would sometimes not work, suggesting another problem. Bad ground circuit was culprit.

[sanibel sailor]

Well I am not as smart as I thought. Did not work this afternoon. Replaced solenoid and new terminal on the switch wire, still no go.

Plan for tomorrow- 1) bypass entire switch mechanism with new switch between batt post on solenoid and switch terminal on solenoid. 2) bypass battery selector switches. If that does not work, I am about out of ideas.

[ShipShape]

Just out of curiosity, did you try turning the key on and off like I described in post #2? I rewired my entire boat when the engine still had the first starter, as in replaced EVERYTHING, and that didn't make any difference to the starter. New starter and solenoid same problem. Started the engine over the weekend and had to turn the key on and off 12 times before it started, and when it starts there is no hesitation, it STARTS.

[FlyingCloud1937]

Originally Posted by sanibel sailor

Well I am not as smart as I thought. Did not work this afternoon. Replaced solenoid and new terminal on the switch wire, still no go.

Plan for tomorrow- 1) bypass entire switch mechanism with new switch between batt post on solenoid and switch terminal on solenoid. 2) bypass battery selector switches. If that does not work, I am about out of ideas.

You still haven't told me.

If the starter has an isolated ground???

It will be clear if isolated it will have a separate grounding stud on the starter to which a ground cable from the neg bat/bus.

Or if the solenoid is isolated???

It will be clear, as there will be 2 terminals on the control side of the solenoid, one will be the pos from the key SW, and 2 will be ground for the control circuit.

Since you seem unwilling to to the voltage drop measurements as I outlined above we will do this the hard way....chasing gremlins

Lloyd

[sanibel sailor]

Originally Posted by ShipShape

Just out of curiosity, did you try turning the key on and off like I described in post #2? I rewired my entire boat when the engine still had the first starter, as in replaced EVERYTHING, and that didn't make any difference to the starter. New starter and solenoid same problem. Started the engine over the weekend and had to turn the key on and off 12 times before it started, and when it starts there is no hesitation, it STARTS.

There is no key, a breaker on distribution panel supplies juice to system, then a push button start switch. I replaced the start switch already. am considering swapping out the breaker. It could bear some improvement, but I would like it to run before I start hanging things.

[sanibel sailor]

Originally Posted by FlyingCloud1937

You still haven't told me.

If the starter has an isolated ground???

It will be clear if isolated it will have a separate grounding stud on the starter to which a ground cable from the neg bat/bus.

Or if the solenoid is isolated???

It will be clear, as there will be 2 terminals on the control side of the solenoid, one will be the pos from the key SW, and 2 will be ground for the control circuit.

Since you seem unwilling to to the voltage drop measurements as I outlined above we will do this the hard way....chasing gremlins

Lloyd

Starter is not an isolated ground design, but ground cable attaches to one of the starter bolts. I am not sure about the solenoid. There are 4 terminals, one small for switch wire, one small unused, one big for the battery cable and one big for a copper strap to starter. The solenoid must be a common design, the auto parts guy fetched one off the shelf without asking what make/model/year.

The unused small stud may be for a ground, although the starter relay on some Fords has an extra terminal to energize the ignition circuit. Should I consider running a ground wire on this small terminal?

[sanibel sailor]

Originally Posted by FlyingCloud1937

You still haven't told me.


Since you seem unwilling to to the voltage drop measurements as I outlined above we will do this the hard way....chasing gremlins

Lloyd

I did check this kind of. I am not sure I fully understood your directions. It has been fairly challenging as the switch is in the cockpit and I am working solo. Had a helper yesterday. Today the switch goes to the solenoid. Putting the probe on the battery terminal, not the cable, at the solenoid and the copper terminal of the ground cable gives me 13+ volts,which i thinks shows continuity, although there may be significant resistance to a highcurrent circuit. When the start switch is depressed, solenoid clicks but the starter motor does not start, this reading drops to about 4 volts. This suggests to me that the solenoid is closing, giving current to the starter which just is not spinning. I believe it also shows good ground circuit.

Any more detailed tests you suggest?

[Group9]

My Yanmar diesel started doing that. I took the starter off, polished the bendix shaft with really fine sandpaper, greased it, put it back on, and haven't had a problem since (over two years ago).

[oldtomcat]

+1 I think you have a problem with the starter. Could be a hung brush or flat spot on the comutator.


OTC

[sailorchic34]

DO NOT connect a ground to the other terminal on the solenoid. I would pull the negative cable off and clean the paint off the metal on the engine where its connected (Starter bolt??).

Also how are your batteries. Have you measured the voltage at the batteries when cranking?

[FlyingCloud1937]

Originally Posted by sanibel sailor

I did check this kind of. I am not sure I fully understood your directions. It has been fairly challenging as the switch is in the cockpit and I am working solo. Had a helper yesterday. Today the switch goes to the solenoid. Putting the probe on the battery terminal, not the cable, at the solenoid and the copper terminal of the ground cable gives me 13+ volts,which i thinks shows continuity, although there may be significant resistance to a highcurrent circuit.

If you're short handed, use two jumpers with alligator clips. use the meter up by the key SW, and then the jumpers clipped down below. You can only measure voltage drop while under load.

When the start switch is depressed, solenoid clicks but the starter motor does not start, this reading drops to about 4 volts. This suggests to me that the solenoid is closing, giving current to the starter which just is not spinning. I believe it also shows good ground circuit.

Any more detailed tests you suggest?

No starter is going to crank an engine when it's only at 4 volts. It should be at a minimum of 9.5 volts while cranking. With strong batteries and high quality, properly sized cables it should be north of 10.5 volts under load.

So you either have bad bats, or bad cables some where.

What does the voltage at the battery do when cranking. If it drops to 4 volts then it's your bats.

Lloyd