Starter hanging

Good deal glade to see all is well and your up and running again.

All I know is I'm glad to see that you are back safe J_I_H. As to the rest or this stuff, I gotta reach for the Beam.

john

79. If he had high resistance in the circuit or a weak battery wouldn't that cause the starter to turn over slowly making the problem recognizable?

By the comments I assume there are no clues as to the source of the problem.

I think my selinoid is built onto or inside my starter. I have never had a Ford starter apart but don't they work the same as a GM starter? Does a Ford starter/selinoid have a return spring somewhere in it?

Hi all. I just got back from an extended work trip - "yuck". It took two cups of coffee to completely enjoy this thread on this rainy Memorial Day morning. Now that theory has been covered let me make a suggestion that will blow everyone's mind. My advice is to check the ignition timing.

Here's my thinking: My experience with sticking auotmotive selinoid contacts is that they fail due to overheat from extended current draw - not from arcing. Also the overheat may cause the selinoid spring to weaken.

So, put on a fresh starter and selinoid and check your engine timing and ingnition system to ensure your engine starts quickly.

If you have your starter rebulit make sure they replace the complete selinoid. A weak return spring is undetectable.

Fix a selinoid? I can't even spell selinoid!

JEFF KOSTIS wrote: A DC motor draws the most current when it is not turning.

Yes, Correct. I thought I said that first.

JEFF KOSTIS wrote: If you kept a 12v motor from turning, it will draw "X" amps at 12 volts. If you reduce the voltage to 6 volts it will draw "Y" amps (less than "X").

Correct, If in both conditions the motors were stalled, yes. But once the motors are turning that model no longer applies.

Yes, under some conditions a makita drill with a weakened battery can generate more destructive internal heat when stalled if you kept bearing down on the work with the same intensity one did when the battery was fresh. Most people let up as the battery weakens. Typically the breakers are sized to only trip when the motor is stalled AND the battery is fresh, which is a different condition.

Practically the same reason brushed AC motors burn up when someone uses a too-long, small guage extension cord, reduced voltage at the tool but plenty of amps available.
Trying to do the the same work with less voltage requires more current, results in more heat, and it "lets the smoke out" of the tool.

For a a 6V and 12V starter to do the same work (nobody changed the engine design) a 6V starter will pull over twice the amps. Thats why 6V starter systems need honkin big wires. I say over because the resistive losses are 4-times higher than at 12 volts.

And thats why 24V starter systems are more efficient and we'll soon see 48V bus systems in autos.

If you had a voltmeter across a starter motor and applied 12 volts to it, What voltage would it ready initially? very close to 0 volts, because it behaves like a short. The faster it spins, the more internal voltage it has, and the less delta-voltage it has with its source, thus limiting the current.

JEFF KOSTIS wrote: I think the confusion is the fact that a DC motor will draw more current as it is slowed down by increasing resistance in the load assuming the voltage stays constant.

Yes, confusion is. Motor resistance decreases with less RPMS, not increases.

JEFF KOSTIS wrote: Another example is a electric DC vehicle winch. Most being the same as a 12v starter motor, if it draws less current with a higher voltage, then they should be able to run it on 24v, or use a 6v motor and run it at 12v. If the current were to be less, that would mean the motor would run OK??

No, it wouldn't run OK for long.   Internally the different starter's brush area, windings, winding wire guage and other factors are sized appropiately for a given voltage, expected rpm, load and duty cycle.

JEFF KOSTIS wrote: If a DC motor draws less current the higher the voltage, then take a big batt charger wih a current meter and hook it direct to a starter motor and note the current from switching the charger from 6 to 12 volts and tell me what happens to the current.

IF the same starter was on an engine, and your charger supplies the abundant current necessry to turn an engine, yes initial current would be higher at 12 volts but just for a moment till the rpms came up, the short duty cycle in that condition causes no damage. Higher current would be demonstated by the 6V application for a longer period than the spinning 12V condition because its labored, humming low rpm condition pulls more amps for a longer duty cycle, thus burning up armatures, brushes, fields and wires.

You are right on about low holding force of the solenoid, from a low voltage condition, being responsible for the contacts welding closed. We just go to help martini find the root cause.

Are we now saying the same thing but still trying to enlighten each other?

JEFF KOSTIS wrote:         Second of all, back to the motor discussion. There is still a confusion between AC and DC motors. Without getting into any lengthy discussions think of this. If a DC motor draws less current the higher the voltage, then take a big batt charger wih a current meter and hook it direct to a starter motor and note the current from switching the charger from 6 to 12 volts and tell me what happens to the current.

No Jeff, re-read what was written.

A DC motor draws less current the faster it spins. That is why the components burn out when the starter drags due to improper wires, underrated battery, etc.
Anything that interferes with supplying rated voltage at rated current will produce inadequate rpms and draw more current because the motor behaves more like a short. High current and low voltage due to resistive losses (a function of the square of the current) produces little work and burns up components. A happy starter sees rated voltage at rated current, producing more efficient power for a longer duty cycle.

Your battery charger scenario is faulty and falls apart when once one adds engine load to the starter.

Put a similar energy capacity 6v battery on your boat and a clamp on ammeter, and if the solenoid has enough holding force at that voltage you'll find the starting system puls more amps at 6V than it would at 12 due to the low RPM of the armature.

I am typically on the mark about such things being a schooled electrical engineer for 17 years.

Jeff don't try and apply ohms law to this application and the bullsh*t way of testing if the solenoid is still engaged or not. The starter is still spinnig so it has to have current going to it and you don't need a damn light to tell that it's still has current going to it. Leave the classroom BS in the classroom all you do is confuse the issue and never solve it.

yes, I am aware of it's function and I will check cable adjustment.

TD, are you saying that if the neutral safety switch is partially engaged, that it may cause a momentary drop in voltage? Meaning it isn't getting full contact, but partial contact because of cable mis-adjustment? I suppose I will be able to check for that when I start chasing/testing the wire from the starter relay.

Fun stuff. Looks like I've got some work to do.

GS, when you say "indadequate actuating voltage" are you referring to the start(yellow with red stripe) wire that runs from the dash(ignition switch), through the trasmission lock out, up to the starter relay?

m87, brand new(not rebuilt, not reman) starter I installed.
JK, It will continue to turn the starter over with key off.
79N,The cables are in fact marine grade but are 2 gauge as I indcated before. I will check and see how hot the cables get when cranking. Cable size and length may be the issue here. I read that 2 gauge is good for 3.6' to 6' lengths(correct me if I'm wrong). I believe I am definitely over 6' with my set up. So, I will check cables for temperature and most likely break down and get bigger cables. The starter relay(solenoid) is in fact marine grade from my local CC dealer, so I know it is the right part. All good things to try, I'll let you all know what happens.

    Several things to check, first, are you sure the starter is not just staying engaged to the flywheel and spinning?? If you shut the key off when it acts up, does it kill the engine, or does it keep on cranking asuming the solenoid is bridged. Also, be sure your new solenoid is a true starter solenoid and not a continuous duty coil stle solenoid as the look identical. Starter solenoids coils draw about 5-7 amps roughly on those styles which are designed to be engaged only for a few minutes before the coil burns out. This causes a harder "throw" and pressure to the contacts making able to handle more current and allowing low voltage engagement with a weak battery.. A continuous duty solenoid has a higher resistance coil which draws only 1-2 amps or so, alowing it to be on continuously without burning up the coil, but has less "throw" and pressure making its current rating about half. Continuous solenoids are not meant for super high current starting. You cant tell the two apart by looking at them.

    Enough on solenoids, you dont have to change the batt cables to larger ones as this will make no difference. In fact, larger cables will cause the starter to draw more current than smaller cables. Remember, the starter is a DC motor, not a AC motor.
     Good luck!!!

                                  Jeff....

I have this same problem. I put three solenoids on last summer and this year it did the same thing.I have know idea. Ive put new cables and a new battery (650 CCA) in and it still does this every now and then.

what's the CCA rating of your battery? and what gauge cables do you have running from the battery to the solenoid, and the soleniod to the starter.

You need atleast 550 or is it 650 CCA's for the battery and if your using 2 gauge or smaller cables replace with a larger CCA rated battery and 0 or 0/2 battery cables. Once the solenoid get's arched once it's going to cause you problems from there on. Seems odd that you have been able to use the solenoid after it has arched.