starter solenoid smokes

[rusty69f100]

Hey forum peeps. I just got a 69 f100 and im also new to this forum. The truck didnt even crank when i got it but i only paid 300 for it. I finally got it to crank when I turn the key (thanks to this site). I noticed that when it was cranking the starter solenoid started smoking. Why could that be?It looks like the alternator has a thick black cable going from it to the +side of the starter solenoid. Im assuming that cable sends the power back to keep the battery charged. my question is why is the solenoid smoking and should the cable be going to the starter solenoid or directly to the battery? By the way its a new solenoid and a new battery and I got a new ignition coil too. thanks for the help.

[Nitekruizer]

to the site!

There are lots of great people here with a very good knowledge of these trucks. To answer your question, yes, the wire does run from the alternator to the main terminal of the solenoid (also referred to as the starter relay) so that itself isn't a problem. I don't know why the solenoid is smoking but, others will chime in and we'll figure it out.

[rusty69f100]

Thanks for that info NightKruizer its good to know that is hooked up right

[1972hiboy]

My first thought would be to just replace it. If the selonoid has corrosion on the contacts internally its going to create alot of resistance in the flow of electricity thus causing heat. pop a new one in and re-try

[rusty69f100]

Thanks 1972hiboy its a new solenoid and its still doing it. I was thinking that maybe the cable from the alternator to the solenoid needs to the same gauge as the cable from solenoid to the battery. I forgot to mention in my original post that ther is also another 2 wires that are on the positive side of the starting solenoid. The colors of them is one red and one yellow. Ill try to take a picture of the starter solenoid

[sargentrs]

I was thinking that maybe the cable from the alternator to the solenoid needs to the same gauge as the cable from solenoid to the battery.

That is not true. Battery cables are usually 4 Ga. The cable from the + post of the battery to the solenoid and from the solenoid to the starter should be 4 Ga. Usually the cable from the alternator to the solenoid is smaller, more like an 8 Ga or a 10 Ga. A smoking solenoid, or battery/solenoid/starter cable is an indication of a bad cable or a bad connection with a cable or it could be the solenoid too. Solenoids are notorious for being bad right out of the box. Take a volt meter, put the black lead on the - post of the battery and then start checking the voltage at the various connections with the red lead. You're looking for a drop in voltage when you try to start. Check from the + post of the battery to the terminal on the post. Turn the key to start and check for a fairly large drop in voltage. OK? Move to the lug on the end of the cable. OK? Move to the lug on the other end of the cable. OK? Move to the nut on solenoid, etc. Get where I'm going with this? You can expect to see the voltage drop a tenth of volt each time you try to start because you're continuously putting a drain on the battery. However, if it drops a couple of volts between connection tests, back up and do it again. If it's consistent, that's the connection that's causing the short and making it heat up. Clean/replace that connection and start over, all the way to the starter. You should also be able to feel the connection get hot to the touch.

[rusty69f100]

Thanks sargentrs. im going to try what you said

[rusty69f100]

I noticed last night that the cable from the alt to the starter solenoid has a cut in the casing of the cable and it was resting on the inner wheel well. Could that be the problem. I wont be able to fix it for a couple days do to the rain.

[sargentrs]

Cause or not, it definitely need to be replaced.

[Lee]

Is the smoke coming out of the body of the relay? Or off of one of the cable connections at the relay?

Also, inspect the cable between starter and relay looking for spots where it may be shorting to the frame or other spot. A faulty starter maybe drawing to much current also.

As suggested I would probably replace the relay too.

[rusty69f100]

@ lee. Its coming out of the positive cable connection of the relay. The cable has a cut in it and I think it may be shorting. Im going to change the cable.