Ground Problems, Sometimes won't start

[Vetteman61]

I'm trying to trace a ground problem and can't seem to find it. I've cleaned the battery post and terminal, as well as the ground and bolt that goes to the alternator bracket. I've also cleaned the positive nut and post on the back of the alternator. It's gotten to when I start it ('87 K5) it will start, and there'll be a click in there. If I drive it into town and back it typically will only click when I get back. If I get it started, it will then start OK. Battery is good. Cleaning the terminals seemed to help, but the problem reoccurs.

Thanks,

 

[Bextreme04]

I'm trying to trace a ground problem and can't seem to find it. I've cleaned the battery post and terminal, as well as the ground and bolt that goes to the alternator bracket. I've also cleaned the positive nut and post on the back of the alternator. It's gotten to when I start it ('87 K5) it will start, and there'll be a click in there. If I drive it into town and back it typically will only click when I get back. If I get it started, it will then start OK. Battery is good. Cleaning the terminals seemed to help, but the problem reoccurs.

Thanks,

If it sometimes just clicks and doesn't actually turn over the engine... you likely have a worn button in the starter solenoid on the side of the starter. It is a round button that physically makes contact with a round spinning disk that is pulled together when you turn the key. The click you hear is the disk getting pulled to the button. If the button is worn from turning for the last 20-30 years, it will no longer make contact and you won't get the starter spinning.

I had this same problem, it started with an occasional click but no spin condition and I finally addressed it when I could turn the key 20-30 times before it would finally catch and spin. I bought a $20 rebuild kit for my starter and when I pulled it apart for the rebuild, that's when I found the worn button. It is the lug that the battery cable attaches to. If you take the solenoid cap off, you can just turn the lug around so the non-worn side is now touching the spinning disk and it will likely work for another 20-30 years before you need a whole new lug.

The top lug in this diagram is where the battery cable connects. When the solenoid actuates, it pulls the disk on top of the plunger towards the lug and transmits power from the top lug to the bottom lug to allow the main starter motor to spin.

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If you take the wires off the solenoid(and the connection from the lower lug to the starter motor) you can then remove the two flat head or small hex screws off the plastic solenoid cap. That will let you access the top lug to loosen the nut holding it to the cap and rotate it 180 degrees so the unworn portion is in contact with the plunger top when the solenoid is engaged.

 

[Bextreme04]

Looks like the price of the rebuild kit has gone up.
https://www.napaonline.com/en/p/ECHSRK104
It has new bushings, seals, and brushes. Sounds like you don't actually need that kit though.

If your lug has already been spun once and you can't just rotate it, or there is any other damage to the solenoid portion, NAPA also sells a solenoid repair kit that has a new cap with lugs, plunger, nuts, etc... for only $38
https://www.napaonline.com/en/p/ECHSTK27

 

[Vetteman61]

Thank you for the reply. This has been driving me crazy trying to chase a ground problem. Though I'd considered the starter, anytime I've seen one act that way it was a battery issue, so I probably would have never thought of that. I'll give this a shot and see how it goes. Thanks again.

 

[Ricko1966]

Volt drop test on both cables and across the solenoid posts will tell the story,no guess work. If you have high volt drop across the solenoid,there is your issue. If you have high voltage drop from battery negative post to engine block. You found your problem if you have high volt drop from battery positive to starter positive,you found your problem. If you have high volt drop from battery positive to solenoid exciter lead,you found your problem. Read up,Google,you tube how to do volt drop tests,it is a very useful diagnostic process.

 

[Vetteman61]

If a bad solenoid stud as described above was the issue, would this be undetectable during a voltage drop test unless under cranking conditions?
Also, this seems to mostly happen once I have started the truck and driven it into town and back, then it won't start. Unsure if it is a heat condition, or just driving into town. It's reading over 14v, so it appears to be charging. I've done a voltage drop test and still can't seem to find anything.

 

[Bextreme04]

If a bad solenoid stud as described above was the issue, would this be undetectable during a voltage drop test unless under cranking conditions?
Also, this seems to mostly happen once I have started the truck and driven it into town and back, then it won't start. Unsure if it is a heat condition, or just driving into town. It's reading over 14v, so it appears to be charging. I've done a voltage drop test and still can't seem to find anything.

It can be a bit sketchy to find this issue with a voltage drop test. You would have to have power to actuate the solenoid(key to start), but not have power going to the main lug on the starter. It would also have to be in the state causing the issue and with it being intermittent its difficult. Ricko isn't wrong, but it really isn't practical to test the actual issue with voltage drop. You CAN rule out other possible causes with the voltage drop test, mainly ground issues or power cable issues from the battery to starter.

If you were consistently unable to get it to crank over, but heard the thunk of the solenoid engaging every time... I wouldn't even bother with voltage drop. I would check voltage at the starter lug to ground with key off, then have someone turn the key to start and make sure voltage is still present. Then while still having the person hold the key to start, you check the solenoid exciter lug for voltage. If you hear the clunk of the solenoid engaging, have voltage at the starter lug, but no voltage at the exciter lug... you have a bad solenoid lug like I described above. The intermittent nature of this issue will make it only show up as a problem some of the time though.

 

[Ricko1966]

Volt drop you take a meter in DC volts mode stick 1 lead on the negative post 1 lead on the engine block have someone turn the key,whatever your meter reads is lost voltage. Lets say your meter showed 2 volts,well you definitely have a ground problem, whether its a bad cable or a bad connection you'll have to do some trial and error cleaning and inspecting. Do the same test but 1 meter lead on battery positive 1 lead on the starter post,turn the key if your meter shows 1 volt you found problem again clean and inspect. Put one lead on starter positive and solenoid out,read your meter. Do the same thing positive lead to exciter lead. I'm going to use some exaggerated numbers to make things clear if your battery has 12v and your meter reads 6volts on any of your tests that circuit can only handle 6volts 12v-6v leaves 6v. Real numbers are .1 volt per connection battery to starter is only 2 so spec would be .2 volts or less I don't get excited about anything less than .5 volt we live in a real world not a book. You don't actually have to run the starter for all volt drop tests but there does have to be a load on the circuit you are testing,so I'll turn on the lights high beams and heater for positive and negative cable. When I say battery post and starter post,that's what I mean,not the end of the cable the physical positive and negative battery post and physical starter post. You can take this further and test from the battery post to the battery terminal if you significant voltage you have dirty connection right there. Many times on a no crank no start,I'll turn on the ignition and headlights,take a meter and poke the center of the negative battery post and the battery cable end,and get a 10v reading and I know right then I need to clean battery post and terminal,if course I check the positive too,they could both be losing voltage.