Complete and utter failure

[Fred Mc]

Some of you may recall I have a GMPD4106 with a starting problem.Cold it starts very well but once warmed up won't even turn over. Its like trying to start with dead batteries, I have bought new batteries, changed cabling(going direct from batteries to starter) had the starter rebuilt,all to no avail. So I decided to get a different starter and tried it today. Same result. The only difference is that the "new" (to me) starter wants to continue to run after the engine starts thus adding further insult to injury. Anyone want to buy a bus cheap!!

[Zephod]

Some of you may recall I have a GMPD4106 with a starting problem.Cold it starts very well but once warmed up won't even turn over. Its like trying to start with dead batteries, I have bought new batteries, changed cabling(going direct from batteries to starter) had the starter rebuilt,all to no avail. So I decided to get a different starter and tried it today. Same result. The only difference is that the "new" (to me) starter wants to continue to run after the engine starts thus adding further insult to injury. Anyone want to buy a bus cheap!!

Well. You've found what the problem isn't. Now to work out what it is. I'm tending toward bearings.


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[Utahclaimjumper]

 Here is the fix that worked for Red Rider: attach a common 12V starter solenoid to the starter housing (make sure its a continuis duty), remove and run the old "switch" wire (from the starter button) to the switch contact of the new solenoid,, run a #10 wire from the battery terminal on the "old" solenoid battery side to one of the main studs of the "new" solenoid,, then another #10 from the remaining "new" solenoid stud  to the "switch"  side of the old solenoid..::  The 50+ year old wiring from the button to the starter solenoid draws about 40 amps to activate the solenoid,, the "new solenoid only draws 2 amps and it in turn puts ALL the available current to the "old "solenoid.. This will eliminate the hot start problem AND the sticking problem..,,  With the old system the voltage drop is so large (and low voltage produces high amperage which burns the solenoid disc ) that the starter AND solenoid sees low voltage..>>>Dan

[Lee Bradley]

Had a 6-71 on a sawmill that did the same thing, start cold and ran fine but wouldn't crank warm.  Fuel delivery truck had mixed gas in with the diesel. Problem cleared up after we finished that 500 gallons.

[Geoff]

Your starter gear is sticking to the flywheel teeth.

--Geoff

[Fred Mc]

I think the stgarter sticking problem is in the solenoid rather than the relay. When I smack the solenoid with a wrench it disengages.

As for the gear sticking to the teeth, what would cause that?

I will try Utahclaimjumpers suggestion.


Regards

Fred

[luvrbus]

It's your solenoid bad the solenoid has 2 winding a pull in winding to engage the teeth and holding winding to complete the circuit to the starter, the holding in winding is bad and not releasing. 

When you change the solenoid check the spring in the nose cone of the starter to be sure it is not broken. I take it you didn't have the starter checked a shop can test the winding on a solenoid      

[Utahclaimjumper]

 The key to your problem is "when smacking with a wrench it releases" The disc inside the solenoid is arcing and burning(welding) from high amperage brought on by low voltage..The disc can be turned over and reused but the problem won't go away unless you deal with the old wiring problem between the starter button and the solenoid... Go to any NAPA store to get a continuous duty (all metal) solenoid.  This is NOT a substitute solenoid,, its used in conjunction with the original unit working together.>>>Dan

[sixtyseven]

I think Dan has hit the nail on the head !   If you want to test his theory before hooking up the relay, you can use a piece of #10 wire as a jumper from your pos. post on your starter to your solenoid (provided you can safely reach your starter with a hot engine and you remember to put it in neutral)  You know, like starting your chevy with a screwdriver.  If it fires right up then hook up the relay like Dan said.

[OneLapper]

Fred,

I have a 4106 too and suffered the same issue.  I replaced every battery cable with 0000awg, replaced batteries, rebuilt the same starter several times.  I finally found a rebuild shop that knew what they were doing, the problem was the starter motor (both starters, as I had a spare I tried).  The windings "leaked" to the outer metal case when hot.  Also, both previous shops had mixed 24v components with 12v parts, which didn't work. 

I would buy a new starter.  The marine electrical shop I finally found had good spares that he used to build me two good starters, but he was fourth shop I used, and the only one that seemed to know what he was doing.

[luvrbus]

Dan's method has been around for a long time it works Mack used it when they had a 24v starter with a 12 v system using the parallel switch  , but you can use a single 12v capacitor for the same results or you can clean the system up.
If some manufacture would make a left hand 39MT starter it solve all the GM starter problems but I don't see that ever happening     

[Utahclaimjumper]

  The problem is normally with the older rear engine vehicles that have 40 to 50 feet of run from the starter button to the starter solenoid. By putting the second solenoid very near the the starter solenoid and taking the power from the main battery cable at the starter you effectively remove all the voltage drop from the two points.>>>D  ( I have to admit this is not my "fix",,we have a very sharp rebuild shop in St. George that will not release a rebuild from there shop under these conditions with out including this mod prewired and ready to go  The return rate after the mod has dropped to zero)

[luvrbus]

Don't the GM have a relay from the switch wire to starter solenoid like a normal bus 

[bevans6]

If the problem was a long run direct from a switch to the starter solenoid, wouldn't using the rear switch eliminate that?  Anyway, don't the switches front and rear just switch a relay, which switches the solenoid?  Kinda what Clifford asked, I guess.

[TomC]

I had a hot start problem, and the problem was solved by tightening the ground wire from the end of the starter.