February 24th, 2010.
RTL434 & others:
If your problem is in the starter solenoid, it is because there are two sets of contacts that must make contact to motor the starter and engage the Bendix. If either malfunctions due to wear, the starter will not kick. This is usually due to mechanical wear and age. The solution is to remove the starter, locate the maker of the starter and model on the builders plate, and contact the usual suspects (Saturn, Memphis, White Owl) for replacements. The solenoid itself new should not run much over 65 or so dollars, neither should the relay immediately above it. If in doubt, replace the whole starter with a new one, White Owl lists them for $325.00 plus shipping, Memphis has them too.
We forget how much beating that the starter button, relay, solenoid and starters take in cranking over these large engines repeatedly, and age and temperature will take their toll on these components. The starter switch needs a diode added to it to divert the back EMF caused by the starter motor when you let the switch go. Once you stop powering the starter motor, it becomes a DC generator while it's winding down, and guess where the surge likes to arc.....? The push button contacts!
Doghead has a article on here about replacing the CUCV starter relay, and his diagram includes the number and positioning of the diode to protect the starter switch from the REMF.
If your engine starts at 32-33-34*F and above consistently, but not at 31*F or below, suspect the starter solenoid first, then the relay and lastly (or firstly, the push button. The starter systems on these trucks are relatively simple. My M35A2 in the photo has had that problem, but lately she has been starting 6 out of 7 starts at below 32*F temperature, so I think the gremlin moved to Acapulco or somewhere, and just checks in for laughs now and then. The truck would NEVER start below 32*F, so the general consensus is- it's the solenoid. The solenoids are not interchangeable between starter motors of different manufactures, so that is WHY you have to check the starter builders plate to get the right one......
Good luck and happy motoring....
Cheers,
Kyle F. McGrogan