Heat soaked starters

["Cadillac Kid" Greg Surfas 15364]

This issue has been previously discussed regarding heat soak starters not wanting to freely turn over but my question here is what does heat soaking do to the actual starter to render it "lazy". Mot asking about cures regarding connections, cables, batteries, etc. but the starter itself assuming it is the correct, longer correct HD starter.
Greg Surfas

[Cadman-iac]

  I think the problem is that the armature and the field windings expand because of the excessive heat, and the minimal clearance between them is reduced even more, causing a drag. I suppose it can also be the armature shaft swelling in the bushings and causing a drag.
 At least that's my theory on this.
 I don't know if the heat has any detrimental effect on the flow of electricity by itself, but I suppose that's possible too.

 Rick

[TJ Hopland]

The ones I have taken apart that had that issue also seemed to be rusty so I assume there could also be some rust jacking going on to further reduce clearances.

I also wonder if maybe there could be something else going on like the heat making the brush springs weak?  I have no idea how much heat that takes or if there is enough there to do it but I can't think of a lot of other things that could cause it.

[LaSalle5019]

The actual problem is summed up here: Rt = Ro (1 + 𝛼ΔT)

The electrical resistance in the starter increases with temperature. This includes the wiring in the field coils and the armature. Since current equals voltage divided by resistance (Ohm's Law I=V/R) the amount of current in your starter is reduced as it heats up. Therefore it has less torque and spins slower.

If you have bearing clearance or other interference issues then you have bigger problems that require new parts.

[Eric DeVirgilis CLC# 8621]

That's also been my theory that it was due to increased electrical resistance from heat.

[Chopper1942]

In the past, starters on vehicles that had high underhood temperatures, like big block trucks, had heat shields attached to the solenoids and diverted exhaust heat away from the starter.  Your battery should be the correct one for your vehicle and at 12.6V. Have the battery load tested with a load tester.  A handheld algorithm tester does not really stress the battery like a load tester does. Check the cable connections at the battery and starter for the B+ and battery and chassis/engine for the B- cables. Make sure there is no corrosion on the small post of the solenoid that attaches to the starter.  If there the screw is loose or there is any arcing or corrosion at this contact, the voltage drop will be considerable.

The best way to trouble shoot the system is to do voltage drops from the battery posts to the cables at the battery (0.1V maximum). Then check from the B+ post to the solenoid post (0.3V). From the solenoid battery post to the starter to solenoid connection. This may run as high as 0.5V. Then check from the battery B- post to the starter housing.  Because this may have multiple connections, it also could be as high as 0.5V.  As you can see, you may only have 11+V available to make the starter operate.

Internal in the starter, make sure the commutator is clean and the brushes good and have good tension. Check the drive end bushing and if loose, install a new bushing.  Install a new commutator end plate and bushing.  Lube the bushing with a high temp silicon grease.

Testing the field coils and armature is a job for a good automotive electrical shop.  This absolutely should be done if you see any evidence of rubbing on the armature or field magnets.

[Seville Life]

I'm with Chopper and LaSalle. It's worth getting new, correct specification battery leads terminals and making sure ALL connections are 100%.

I also think something we can often miss are the earth straps from engine to frame and variants. These need to be strong and have clean contacts. Likewise electrical parts on the car with their own earth, make them clean and tight, so many electrical annoyances can arise from poor earths.

Finally the right battery with right cranking power and know your alternator is pumping out correctly. Add to that properly tightened fan belts. Regarding all of the above, sit in traffic, Climate on, baking heat, just idling and it will be these things done right that'll save you.

["Cadillac Kid" Greg Surfas 15364]

Restating my original post. ALL the cables, connections, battery, etc. are correct. I was asking exactly what IN THE STARTER gets heat soaked and causes the "lock up"?
Greg Surfas

[Cadman-iac]

The actual problem is summed up here: Rt = Ro (1 + 𝛼ΔT)

The electrical resistance in the starter increases with temperature. This includes the wiring in the field coils and the armature. Since current equals voltage divided by resistance (Ohm's Law I=V/R) the amount of current in your starter is reduced as it heats up. Therefore it has less torque and spins slower.

If you have bearing clearance or other interference issues then you have bigger problems that require new parts.

  I used to know ohms law, but that was 40 plus years ago. Haven't had need of it since, so it was forgotten.
 Good call.

 As for what can be done about this, shielding and better airflow around the starter are about the only things, unless you upgrade to larger cables and a heavier battery with more cranking amps.

 I know that some cables are not as large as they appear due to heavy insulation, and some are just copper coated aluminum, which are junk in my opinion. Not even sure why they went with aluminum except for the weight savings.
 I suppose you could find a starter that has  bigger field windings that can create a stronger magnetic field.
 If you haven't taken your starter apart yet, check the armature for wire separation at the commutator. I've seen some where the solder has been overheated and the wire separated from the commutator bar, effectively killing one loop of your armature windings. It will still work, just not as effectively.
 Another cause for this is over-speeding of the starter if it gets stuck when the engine starts, but this is rare. I only make mention of it because it frequently happens to my old '53 Ford tractor. Fortunately it doesn't rev enough to cause any damage to the starter.
 Just something to think about anyway.

  Rick

[Eric DeVirgilis CLC# 8621]

On a side note, I've never seen a post '76 Cadillac model with the same issue.

[Cadman-iac]

 Greg,

 I noticed that your second post says your starter "locks up", but you only mentioned it being "lazy" and "dragging, or not turning freely".
 Does it actually lock up solid, or drag excessively?
 The locking up is a clearance issue.
 Have you taken it apart and inspected your armature for any unusual marks around the outer surface, like it's been hitting on the field windings? Or any scoring on the surface area for the bushings?
 I'm guessing that you have good brushes and springs as TJ mentioned.
 I honestly can't think of anything else that would make it lock up.

 Rick

["Cadillac Kid" Greg Surfas 15364]

Just drags. Sorry for the misque
Greg surfas

[Cadman-iac]

  Another thing that might be causing the problem is your solenoid. If the copper washer that makes contact with the terminals in the cap once it's energized is pitted or worn somewhat, it will add more resistance to the circuit. This has been mentioned before just recently if I remember correctly. You can fix this one time by flipping the washer over so it uses the opposite side. Something else that you might need to do at the same time is to rotate the contact terminal studs as well. The washer only contacts about half, maybe a little more of each terminal, so if the washer was contact burned,then the terminals would be as well. The terminal that the battery cable goes on is the easy one to rotate, since it doesn't have anything else connected to it internally, and if memory serves, neither does the other big terminal that feeds the current to the motor.
 The solenoid terminal has a small wire connected to it, but it can still be rotated so it gets a better contact. The relay terminal, if it has one, (not all do), shouldn't have any wire connected to it internally, and it can be rotated for a better contact as well.
 As a side note, for those of you who have a power supply problem while cranking, this may be your problem. The terminal is not getting a good connection between it and the big washer when your starter is engaged. Just something that you might want to check if you're not having any luck tracking down your power problem. .

 Hope this is helpful. .

 Rick

["Cadillac Kid" Greg Surfas 15364]

Starter has new armature, new brushes and brush holders solenoid is NOS. NOT A POWER ISSUE IT IS JUST A QUESTION OF WHAT IS DRAGGING. going to a local starter rebuilder this week and ask them. I'll get back with their opinion
Greg Surfas

[Cadman-iac]

Starter has new armature, new brushes and brush holders solenoid is NOS. NOT A POWER ISSUE IT IS JUST A QUESTION OF WHAT IS DRAGGING. going to a local starter rebuilder this week and ask them. I'll get back with their opinion
Greg Surfas

 Ok, you hadn't mentioned any of that earlier, so it was all speculation.
 It would be very interesting to see what the rebuilder says, because I'm sure everyone has experienced this issue at least once before.

 Rick

[mario]

Another thing that might be causing the problem is your solenoid. If the copper washer that makes contact with the terminals in the cap once it's energized is pitted or worn somewhat, it will add more resistance to the circuit. This has been mentioned before just recently if I remember correctly. You can fix this one time by flipping the washer over so it uses the opposite side. Something else that you might need to do at the same time is to rotate the contact terminal studs as well. The washer only contacts about half, maybe a little more of each terminal, so if the washer was contact burned,then the terminals would be as well. The terminal that the battery cable goes on is the easy one to rotate, since it doesn't have anything else connected to it internally, and if memory serves, neither does the other big terminal that feeds the current to the motor.
 The solenoid terminal has a small wire connected to it, but it can still be rotated so it gets a better contact. The relay terminal, if it has one, (not all do), shouldn't have any wire connected to it internally, and it can be rotated for a better contact as well.
 As a side note, for those of you who have a power supply problem while cranking, this may be your problem. The terminal is not getting a good connection between it and the big washer when your starter is engaged. Just something that you might want to check if you're not having any luck tracking down your power problem. .

 Hope this is helpful. .

 Rick

Greg:
I know you don't want the fix; however this would explain why a Ford fender mounted solinoid  would fix the dreaded gm heat soak problem.
Ciao,
Mario Caimotto

[Cadman-iac]

Greg:
I know you don't want the fix; however this would explain why a Ford fender mounted solinoid  would fix the dreaded gm heat soak problem.
Ciao,
Mario Caimotto

 Mario,
 How does adding an extra solenoid fix this problem? The link you have just goes to a picture.

 Rick

[Eric DeVirgilis CLC# 8621]

I've seen Lincolns with fender mounted solenoids do the same thing.

["Cadillac Kid" Greg Surfas 15364]

On the GM starter the solenoid pulls n the Bendix AND makes contact feeding the field coils battery voltage, so it cannot be fender mounted.
Greg Surfas

[TJ Hopland]

Anyone know why sometimes they were separate?   Seems like in the 90's even Ford got away from that design.  Was it just to make it easier to replace?  Maybe get it in a slightly cleaner and drier location?