The starter on my brother's old 400 explorer started acting up this weekend and I just got in from trouble shooting it. I found the connections at the solenoid worn and corroded so replaced all of them; I then found the 12 volt wire to the key switch corroded in two and replaced it.

What I have now is the solenoid will click once, each time I hit the starter button, but the starter will not turn. So I checked to see if I get 12 volts on the starter side of the solenoid when it clicks; I found that I only get 5.6 volts across to the starter side and have over 12 volts on the battery side of it.

I know the solenoid is probably carboned up inside causing a weak contact; I'm thinking about drilling the rivets off the solenoid, cleaning the contacts inside, and riveting it back together like we used to do on the old fords back in the 70's. My question to you OPT, is can it be done on one of these solenoids or are the contacts so small they can not be cleaned up? thx.....

 

As most techs would do,I would JUST replace it and get on to the next job as we didn't have the time to experiment or tear into small replaceable components!! But if you have the time and desire,tear into it and see how it ticks. Your findings might help others if they want to do the same thing!! OPT PS: NOT trying to be rude,but when a shops labor rate is 95 dollars an hour,the time involved into trying to repair the solenoid(if possible) would cost more than just replacing!!Plus if the time spent DIDN'T help repair the solenoid would the customer foot the "extra" labor plus ending up installing a new one also?? That's why we just chunked em! Sounds kinda cold,but thats how most shops are,especially if the tech works on a "flat rate" basis. PLUS again anything you find,just post it for the other guys!!

 

hello,i tried to take mine apart,but the very thin wires inside just broke apart.

 

Yeah Doc, I was afraid I'd find things to be pretty fragile inside there, I'll probably just replace it, but not before I peek inside to see what I can do with it; I'm a retired aircraft mechanic with too much time on my hands for my own good sometimes.

And your not being cold OPT, I was an aircraft mech for 24 years and moonlighted as an auto mech for 17 of those years, so I understand all about the labor factor.

 

being you have the time id take it apart,...if wires are so week thay crumble theres a good chance that theres the volt drop,soulder an wire ant costly,...but id be buying a new one even if you fix that one,...an have it ready!

 

I replaced the solenoid with a new one today, which of course fixed the starting issue and as promised I tore into the old one to see what was the cause for the failure.

I drilled out the four small rivets that hold the bottom plate on the solenoid, which exposed the signal coil wires where they are soldered; one to the switch signal contact and the other to the ground plate. I used a soldering iron to remove the signal coil, allowing me access to the main contacts, which come right out after removing the external nuts mounting them to the housing.

I found that it was dry inside the housing, but water had gotten into it at one time or another and had caused some greenish corrosion to occur on the bridge contacts; there was also the usual carbon build up on them as well. I found the wires on the signal coil to be in great shape with no corrosion what so ever.

After my internal tour of this little solenoid, I've come to the conclusion that you can easily repair one by cleaning any corrosion and or carbon build up off of the contacts, reassembling, resoldering the two signal coil wires and then installing 4 new pop rivets.

I would also suggest sealing around the two post contacts, where they protrude from the solenoid housing, as well as around the base plate with some RTV sealant, to prevent water from entering and causing the problem again. The contact posts have o ring seals on them, but I found mine to be in questionable condition upon disassembly and suspect the water got in past them.

Here is a shot of the three corroded contacts that were causing the voltage drop. The left one is on the signal coil and when energized bridges the voltage across the other two contacts; one being 12 volts from the battery and the other going to the starter.


Here is a shot of the solenoid completely disassembled

 

You would have made a great surgeon!! You MUST have loved dissection if you took biology class!! Pics are great!! OPT

 

LOL OPT, it's from all my years of wrenching on aircraft, there are many components on them that are overhauled every 300 hours and even a lot of the components that are swapped out when found defective, are rebuilt and turned back into the supply system serviceable.

 

wow, and i thought i like taking stuff apart.