<VV> Maybe the starter.

[Jay Maechtlen]

yeah, this is an old thread-

if you have a starter out, you can see pretty clearly if the bushings 
are good or not - see if there is side play of the shaft in the bushing.
They shouldn't ever get bad enough for the armature to drag, but they can.

The solenoid - easy stuff, look at the contact plate and its contacts. 
If they are rough, smooth them off.
Some solenoids you can flip the plate to get a fresh surface. Of course, 
someone may have done that already.

Commutator - it can wear and so can the brushes. If you replaces the 
brushes you should resurface (typ in a lathe) the commutator.
Of course, if its not too bad, you could prob just run the sucker 
unloaded (on the bench) for a minute or two to let the brushes seat.

BTW- should certainly grease the bushings - don't know what's best, but 
wheel bearing grease or general purpose white lithium grease would be 
much better than nothing.
cheers
Jay

On 8/8/2020 7:46 PM, FrankDuVal via VirtualVairs wrote:
> You are confusing several comments.
>
> 1. A cold engine does turn easier than a hot engine. Now, a frozen 
> engine, as in low temperature frozen, does turn harder! Cold for this 
> discussion is 70 °F or 21 °C. For our California members! This frozen 
> slow crank is mostly oil viscosity related for frictional loss.  Even 
> the oil in he starter bushings, and anything else turned by the 
> engine, like transmission input gears. Add to that the harder to move 
> fuel, and harder to atomize fuel at frozen temperatures. Diesel fuel 
> gets hard to move at 16 °F   (-8° C). BTDT. :)   And then if there is 
> water in the fuel.....It doesn't move at all!  BTDT also....:)
>
> 2. A hot starter also turns harder than a cold starter (again, cold as 
> in not yet running today, not winter time in Minnesota).
>
> 3. Worn parts like bushings in starters allow the armature to be out 
> of position due to magnetic forces acting upon it. Hence the pole 
> piece marks on armatures with worn bushings.
>
> 4. Worn bushings + drag of armature on pole pieces makes it harder to 
> turn.
>
> 5. A mechanical piece of equipment that works OK when cold but not OK 
> when warm is a temperature related problem. Worn parts change shape 
> due to heat (as do perfectly fine parts), so a marginally OK starter 
> suddenly becomes a not good starter because of heat. And as soon as it 
> and the engine cool down, works fine again. But of course, it is not 
> working fine, but does start the engine so it does not yet get 
> replaced, even though it is worn out.
>
> 6. No one said the engine alone got so hot the perfectly fine starter 
> could not turn it over. The starter is bad, the engine is not, just 
> operating normally as a warm engine, needs more umph to turnover when 
> warm.
>
> 7. Not mentioned yet, but related to worn bushings, is starter drive 
> to flywheel clearance. It might be possible the magnetic forces on the 
> armature cause it to shift enough in worn bushings to close the gear 
> gap, causing more frictional loss. When cold, maybe that force is less 
> due to the engine turning over easier. Starters are series wound 
> motors, the more the load, the more current they draw, the more 
> magnetic force increases inside on the armature.
>
> 8. The only proof is that just changing the starter fixes the problem. 
> So, the proof of what is wrong with the starter is change a part at a 
> time and retest! Who has the time and energy, so just put bushings and 
> brushes in and call it a day! Ha!
>
> I like having discussions.
>
> Frank DuVal
>
> On 8/8/2020 3:51 PM, Hugo Miller via VirtualVairs wrote:
>> And the notion that a heavy diesel engine with over a million miles 
>> on the clock would be so tight at normal running temperature that a 
>> massive 24 volt starter cannot even turn it over - well that is 
>> frankly laughable. I am equally certain that an engine at normal 
>> running temperature will take less effort to crank than a cold 
>> engine. I thought that was universal knowledge, so obvious that it 
>> wouldn't need stating. The Wehrmacht found that out to their cost at 
>> Stalingrad. 
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Jay Maechtlen
61 Corvair coupe
custom fiberglass skin
GM3800 supercharged
4T65E