Just made a post and lost the whole thing ? Try again. All good suggestions. I will jump a cable across the solenoid when starting and see what happens. Also will clean all connections, check voltages when turning over the engine and reread and think about the other comments. May try a good remote ampere meter and record readings. Large cable is in place from battery to solenoid and then to starter. Looks like copper welding cable. May be size 00.
First make sure the car is out of gear and the ignition is off!
I can't remember if you said that if when its hot the starter Bendix is or is not pulling in and engaging the flywheel, but not cranking?
I imagine this is still a positive ground system since its still 6-volts. So everything is backwards from what your use to. It messes with my head too. I'm so use to working on negative ground systems.
I always breakdown an electrical diagnoses into four sections. There is the battery. There is everything between the battery post and the starter terminal. Then there is the starter (the load). Last everything between the starter ground (the housing) and the ground terminal of the battery. You go after each one of these separately. Just work on one section at a time Don't worry about any of the rest of it. You go after what you can check for "free" first before start assuming a part is bad.
1. You always start with the battery. Because 95% of the time that's where the problem is. You can check it for free by turning on the headlights and seeing if they go out when you try and crank it. Both when its cold and when its having the problem. If the head lights go completely out the battery could be bad or discharged. You should check it with a voltmeter but if you don't have one the headlight test is better than nothing. I have not read where you have tried the headlight test. Try the headlight test on your daily driver and see what they do. It will give you a good idea of what a good battery should look like.
You should still go out and buy a meter. Right this minute! There are some really cheap digital meters. They will probably work for you need. "Do not" use them on a computer controlled vehicle. Do not use an analog (with a needle) on a computer controlled vehicle. The circuits are literally microscopic inside that computer. The meter, just by itself can draw enough current though those tiny computer circuits to damage them. You have to buy a meter that is designed for working on computerized cars. Most people buy a Fluke meter that work on vehicles for a living.
2. Now were stuck you can't do this test without the voltmeter. But you went out and bought a voltmeter so now we can continue.
You need to know how to setup your new voltmeter. The one you just bought!
This is how hard this is. Stick the batteries in the meter. Turn on the meter. Turn the voltage scale switch on the meter to the next higher scale than the voltage you want to test. I think I use the 30 Volt scale when I'm checking for 12 volts. If you have it on the wrong voltage scale it won't hurt a thing. Your reading will just be screwed up. On the second switch You have an AC and DC scale . AC is for the house DC is for your vehicles and batteries. Turn the switch to DC. You have two leads, one red, one black. You have a plug marked common or the "-" symbol, stick that black lead in there. Now you probably have two holes left, One for amps and one for volts (+). You might not have the amps plug on a cheap meter. Even better, you will never use it. Plug the red lead into the (+) hole. You are now ready to go. You cannot hurt the meter except on the resistance scale. You do not check for resistance while voltage is present. Its best to just disconnect the battery cable. Resistance is the little omega symbol. Don't plug anything in there and your good. Maybe one more thing I should mention, you should not use your new meter as an ammeter on a large circuit. For now its just better you never use it Never disconnect something and then put you meter leads between those two disconnected spots. When you do that all the amperage will try to got through your meter and it cannot handle it.
You will never use the resistance scale unless your measuring the specification of a resistor. The only time that will happen on an old car is on the ignition resistor. So forget all about ohms and all that stuff. You should eventually know it but for now don't worry about. Without going into it too deep you cannot check the resistance of a battery cable with a ohm meter to see if it is good. I'll give you a quick example, you check the resistance with your meter on a battery cable and it says its good , zero resistance. Is it really good? Your putting a tiny bit of electricity through the cable from the voltmeter's batteries. Its going to have no problem finding its way through that giant cable, even if the cable is 99% bad. The meter is going to read zero resistance because there is zero resistance for that tiny amount of electricity. What happens when you crank the engine and your pushing 300 amps through that cable. That 99% bad cable is not going to be able to handle it. Its like a plugged water pipe. A trickle could get through the pipe but not a flash flood, 300 amps is like Niagara Falls trying to flow through that cable.
Yes, electricity flows just like water. If its not flowing it won't spin the starter. If not enough flows it turns too slow or not at all. The only way we can check the cable for resistance is to do a voltage drop test. That just means checking for how much voltage is not getting through that cable when the starter is trying to crank. How do you figure it out? You stick your leads on each end of the cable while your cranking. Your voltmeter reads 4.00 volts. What that means is only 2 volts of pressure is making it through that cable. Remember voltage is pressure. Its not some kind of magic, its the measurement of electrical pressure. Don't overthink it.
The meter just feels the 4.00 volts of pressure that cannot flow through the cable. Just like a water pressure gauge. You can't see it and its too small of a pressure for you to feel it but its there. The meter tell you it is. If you don't believe there is electrical pressure in a circuit try higher pressure, like a spark plug wire. We started with 6 volts of pressure, 2 volts made it through the cable 4.00 volts did not. We now know where that 4 volt blockage is. What do we want to see in a cable, we want to 0.00 volts. zero pressure in that cable, zero resistance while its operating the starter.
If 6 colts leaves battery. We need to be able to find all six volts in the circuit. We do the voltage drop test. Every little pressure drop should add up exactly to the pressure that's in the battery. Ideally the only pressure drop would be the starter. If you put the leads across the starter while its trying to crank you should see almost the full 6 volts of pressure being used at the starter.
Go get a flashlight, 9V, AAA what ever you have. Lets say its a 9V battery. Stick the red lead on the plus side of the battery. Stick the black lead on negative side. The meter should say 9.00 volts. That have now mastered the DC voltmeter. You don't need to know anything else about it except to turn it off when your done. I take the batteries out of mine.
Perform voltage drop tests across "every single" big cable, little wire, connection point, switch, wire spice, , starter solenoid. foot mounted starter switch, anti-theft devices…. Every spot where separate parts touch each other. Then test every one of those separate parts. Everything between the negative battery post and the terminal on the starter. That includes a wire and its crimped on end. That includes a drop test between the battery post and the battery cable end, that is very first spot you would start. Then you just keep moving towards the starter doing voltage drop tests. If you find a drop you clean the connection or replace the part.
3. The other side of the circuit. which in this case is th positive ground side
You could jump a cable from the "negative" battery terminal directly to the starter post connection. Make sure you connect to the battery terminal first. That's a lot of amperage going through that starter cable. Its going to spark a lot, like a welder, when you first start to clamp onto the starter terminal. If this spark were to occur at the battery you could have an explosion. Especially if you have been charging the battery and its "gassing" ( when you can smell the battery fumes) this is a sign that you are trying to overcharge the battery or charging with too high of an amperage. If you can smell those fumes so can that spark, and it could do the boom-boom! That's what I tell my one-year old grandson a hundred-times-a-day, "your going to do the boom-boom"! You want to control where that spark occurs, better it happens down at the starter. If there is no spark that already tells you something is wrong, for some reason the current cannot flow. Bad starter or bad positive ground side of the circuit. That tells you its not a tight engine or it would be sparking as the current was trying to crank the engine
It sparks because as the jumper cable clamp starts to make contact with the terminal all that amperage is trying to flow through those tiny contact points, the treads on the terminal lug and the little tips on the jumper cable clamp. The amperage starts melting them (its a welder at that point) until the clamp can make a good enough connection that the amperage can finally all flow through it. You might freak out as soon as you hear the cracking boom of the electricity jumping the gap. Its a miniature version of thunder, at the same time it look likes you have just done something really bad. You have not, its normal and it will stop as soon as cable clamps with enough pressure. One warning, if the cable starts to glow red and smoke rip that cable off as fast as possible. Then go bandage your burned hand. It happens instantly. You have a complete short to ground inside the starter.
If the starter is good and the "positive ground circuit" is good, the starter should spin, unless the engine is locked-up which it sounds like it is not. I was thinking, just for the fun of it, you could put a torque wrench on the crankshaft pulley bolt and compare the torque needed to rotate the engine when it is cold and then again when its hot. It would be interesting to see if there is any difference?
Back to the starter. If the starter still does not spin take the other jumper cable and "first" connect it to the positive terminal on the battery.Make sure the starter bolt is clean and bare metal. Take the other end of the cable and clamp it directly to that starter mounting bolt. It could spark again as you complete the circuit. It should crank if the positive ground side of the circuit is bad.
Now you have bypassed everything there is in the entire starting circuit except the battery and the starter. If the battery is good than the starter is bad. Like I said in previous post you can try tapping on the starter with a hammer and it might spin but its still bad. You don't want to try and return a starter you have beat the crap out of. The hammer, rock or whatever you can find to beat the hell out of the starter trick is for emergency situations when your prospecting in the desert 50- miles from civilization. It usually only works one time so don't shut off the engine again. Somebody has to be trying to crank the engine at the same time you hit the starter.
Make sure you have good battery cables. I grabbed a cheap set at work one time and they were no good They had an open inside of them. That really messed with my head until I figured out the cables were bad. After that I only bought the best quality jumper cables I could find. Heavy cable with good quality clamps on the end with lots of clamping force.
Its taken most of us gearheads 50-year's or more to buy all the tools we use and there is never an end to it. I tell a guy to grab a torque wrench ,voltmeter, jumper cables and we just assume everybody else on the planet has this stuff. Why would they have stiff stuff if they never worked on cars before. If your young and you think your going to continue to work on cars as a hobby you need buy these tools as you need them. I don't borrow tools or rent them. If I need a tool, I go buy it. If I use it once, it probably paid for itself. If you don't need the tool "right now" buy them used at Estate Sales and Swap Meets. You can buy ten-times the tools for the same money, quality tools. You can buy those big heavy America Made tools that nobody wants to inherit because they are hard to move and they take up too much room you can buy for a fraction of the cost. But you need to be there first inline at the Estate Sales or Swap Meets to get the deals.
