Starter Problems

[gus]

Gary,

What JR and I both are trying to get across is the importance of the voltage at the small terminal on the solenoid. When you use the starter switch - you should have 24v.

The large solenoid terminal is directly from the battery so it is very seldom the problem, but can be.

The small terminal is another story. It meanders from the bus run (Or master) switch to the starter switch to at least two electrical panes terminals (Excellent places for corrosion) to the relay to the solenoid. There are many places along this path for corrosion or other types of poor connections to sap the voltage so much that the solenoid doesn't have enough left to strongly move the solenoid plunger.

You can also check the front starter switch circuit using the engine room starter switch. If it spins the engine normally then you know the front starter switch circuit is faulty because the engine room starter bypasses most of the starter switch circuit - except the starter relay.

The main thing about on the large solenoid contacts is that they be clean. However, it takes a lot of corrosion to affect this voltage because it comes directly from the battery via very large cables.

On the other hand the starter switch circuit is all small wires coming a very long distance so it takes very little corrosion or poor connections to weaken the whole circuit.

It hasn't been too long ago that I went through almost this same exercise and it was all caused by corroded terminal connections and some corroded wire.

I also went through the same thing with my engine run circuit - my engine would stop when I hit the brakes or used the turn signals!! I could write a book about what happened next but I won't.

[JohnEd]

Gary,

Do you remember when a mech would reach under the hood and, with a simple screwdriver" wedge the metal between the big bat terminal on the starter and the small terminal that was the ignition "signal' to engage the starter.  If the starter engaged and turned over the engine the "problem" was in the ignition or starter solenoid circuit.  If the starter engaged he would take a pair of slipjoint pliers and short across the solenoid, if it had one.  If neither of these get the starter going you are almost there in finding the problem.  The last step is to measure the voltage at the starter "post"  while you tried to engage the starter.  That voltage should be at least 20 volts while engaged and 24 when not.  YOU CAN have a bad battery connection cause your symptoms and it isn't that rare of an occurrence in my experience.  But others are correct that it is most probably the switch.  Clean your bat terminals and connections anyway while you are in there and grease everything with "silicon" grease.

HTH

John

[Ncbob]

The 40 MT and 50 MT Delco starters seemed to be plagued with brushes that did not wish to stay seated from time to time...That happened to me about a year ago coming back from the last Timmonsville rally.
I'd pulled into a rest area and shut the bus off for a strtch of the legs and when I wanted to leave the engine didn't want to crank.

A smart rap with a hammer fixed the cranky starter...it cranked and I came home.  The same starter is on the engine and haven't had a problem with it since. Perhaps I got its' attention.

Bob