starter wiring question. Solenoid function questions.

[Erik Jenkinson]

So I went and bought one of those chinese gear reduction starters to hold me over until I can find time to rebuild my 27mt. I took out my existing starter,which has really begun to rattle hard after every start. I put in the chinese gear reduction, with the correct bracket, and it fired right up. I repeated the process several times, no problems. The next day I went out to move my truck, and I got the click, but no go. I ended up just putting the original, near dead one back in just to get the truck out of the driveway. Here is where my problem lies. I am nearly certain I may have in haste, wired the small wire going to the solenoid on the incorrect side. My original starter has this wire on the right, or closer to the center of the vehicle. Im pretty sure I put that new starter on with the small wire on the left. Nothing fried. No apparent damage seems to have occoured. What difference might wiring it wrong have made? It did work, several times. Did I just torch it, or will changing the side of that wire get me up and running again? I have done the doghead mod. Worse comes to worse, I think I'll go with a Wilson rebuild, and make sure I wire it right. How does wiring /flow of electricity affect the starter and solenoid? Might this chinese one still be "good"? I really need to understand how a solenoid reallly functions, so I dont do anything stupid again. Im wiring up something I dont really even understand. I should mention that the chinese gear reduction starter ony gives you the option of putting that wire on the left side. The other side just has a small bolt where the stud would be. At first glance these dont look interchangeable.

 

[cpf240]

If it worked, then it was probably wired correctly.

That solenoid is really just an electromagnet. In a DC circuit, it will either "push" or "pull" the shaft in the middle of the coil. So, if it worked and engaged the starter to the flex plate, then it was wired correctly.

I'd guess that something failed in the new starter. Is your truck still running 24v to the starter? Is the new starter rated for the voltage being supplied to it?

Sometimes you can get a 24v starter, but have the wrong, 12v, solenoid on it.

What sort of warranty does it have?

 

[marand9199]

Erik, I assume you have your truck up and running by now. If not here is a very good explanation with pictures on how the solenoid works and how to repair it.

http://www.dieselplace.com/forum/63...ngine/140514-how-repair-starter-solenoid.html

 

[Warthog]

Just an FYI.

On a starter solenoid, there are usually two small terminals. This is a hold over from the old days when gasser engines used the old style ignition coils and points.

During cranking the ignition coil can use and "extra" kick in the pants to provide a hotter spark. So on a 12v system, a full 12v is sent to the coil. When the key is in the run position only 6v-9v is sent to the coil (inline resistor drops the voltage). If the full 12v was sent to the coil all the time, the coil would burn out quickly.

The "S" terminal is used to send voltage from the battery to the solenoid, The "I" or "R" terminal is used to send voltage to the ignition coil only during cranking.

On a diesel engine there is no coil so the "I" or "R" terminal isn't used. You only need the "S" terminal.

 

[Warthog]

Erik, I assume you have your truck up and running by now. If not here is a very good explanation with pictures on how the solenoid works and how to repair it.

http://www.dieselplace.com/forum/63...ngine/140514-how-repair-starter-solenoid.html

Another FYI. This repair works great on the 27MT (direct drive) starters and the Deuce/5-ton starters. However the 28MT (gear reduction) starter solenoids are sealed. They are not servicable. I have broken a couple of them trying to take them apart.

YMMV

 

[Erik Jenkinson]

Here was my own trial and error process: I purchased the first gear reduction starter from DB Automotive on ebay. I installed it (correctly) and it lasted maybe five cranks. Returned it, got a new one. That one lasted about 1/2 of a crank. I ended up getting my money back for both, and purchased a rebuild kit for my existing direct drive starter. The rebuild was pretty simple. Now that thing fires up so quick its crazy. End result? Never ever for any reason purchase junk Chinese starters. Do the work. Rebuild it yourself.