Had the same problem with my OT Chevelle, started fine when cold but wouldn't crank when hot. It has a stock Goodwrench 350 in it and I chased down every possibility but the problem turned out to be the starter. Put in a reman and that totally solved it.
Open circuit voltage tells you very little. My voltmeter goes down onto the 9+ volt range as I'm cranking the engine. You need to measure the voltage at the starter, not on the solenoid, but the wire connected directly to the starter, while it's engaged. You may have a faulty connection in the solenoid. You should also measure the voltage drop from the starter ground, which is the engine block, to the negative post of the battery (the actual battery post, not the terminal on the post) while you are cranking. Anything over a few tenths of a volt indicates a problem. Since your engine has started reliably in the past, I would believe that the wire size isn't a problem.
I sped through this, and may have missed something; did the starter continue to draw current and just not be able to turn over the motor, or was it completely dead, as if it had no current going to it at all?
Its always amusing how many change this , replace that , add this , throw $$$ at it answers are posted with a lesser number offering ways to diagnose the problem so you'll know what to repair . What sort of ignition switch is being used ?
& Does not seem to many Do Not know how to Size battery specs for their needs, The Spec 's The reserve( like gas in yr tank) @ how many Amps per Hour
Ok, I'll be the hillbilly here. Of course it has to happen again to see if it works but it can point you into a direction. Sounds like you indeed have good electrics so we've got an anomaly. It may very well have been just a perfect storm of distributor plate stuck advanced be it weights or vacuum. How hot was it that day? Waited 3 min and maybe the distributor cooled just enough to release the stuck metal and you were all set. And, it hasn't happened again. Everything is everything. So if it was too advanced to start in that moment, sometimes you flood it just a little, the motor speeds up cranking and you're off and running with a very little argument at idle that cleans up immediately. I know, really back alley shit, huh? The worst it could be is a warped plate in the battery that shorted because it too was hot but also cooled enough. How old is the battery? I'm of the opinion you had a rare occurrence of just the right little thing stuck, hot motor besides, enthusiastic compression but not excessive, and all combined to just momentarily give you the finger because it was just being a dick. It's your car, all seems well, what do you think given those thoughts?
The correct answer is in these three posts. They usually get it right and don't BS people just to be raising their hand in class. Those Skinny #4 "12" volt cables from the parts house don't carry enough amps to start a V8 with a starter that is a bit heat soaked. Been there, done that own the greasy shirt and a starter I replaced because I thought it was bad but it was cables and not starter. Bad grounds especially where the cable contacts the block because you did not scrape that pretty paint off the block good enough because you didn't want to mess up your perfect engine paint job. Bad connection at battery or at starter. I've bought one of this style of digital read out test light to put in the tool bag in each of my vehicles with some being fancier than this one or at least costing more money but they not only tell you if you have power there they tell you how much power you have or if you have a resistance causing a voltage drop. You can probably get one at the local parts house now but Amazon has a ton of them from 8 to 30 bucks. Right now if you have those skinny "12" volt cables on it replace them with # 1 0r 2 cables and that should be a big help. The other thing is that if it is a Chevy engine and starter make sure that the wire to the S post on the solenoid is large enough gauge, I'm thinking some kits skimp on wire size and that circuit needs the amps to be able to kick in the solenoid, the same reason a lot of us have gone to adding a Ford Solenoid. Doing that gives you full amperage to the Chevy solenoid.
While I can appreciate when one's opinion is met with...skepticism, I wasn't offering an opinion. I just asked a question. I beg to differ. Based on personal experience, and off the advice of a solid mechanic, which admittedly, I'm not, it matters. Mine was a HEI failure. Fixed with a new cap and rotor. I asked google... -Yes, a short circuit in an HEI distributor can prevent an engine from cranking, or it can cause the engine to crank but not start, depending on the nature and location of the short. A short can cause the ignition system to not power up, preventing the starter from engaging or the ignition system from receiving power. Conversely, if the short is in the cap, it could cause a loss of spark to the plugs, leading to a cranking engine that won't fire" The problem is, parts are being change before an actual diagnosis can be made as to what is the problem and what's causing it.
Possible but not in this case. In a situation that it fires On all cylinders "at one time" it will act like a hydraulic lock cylinder,s & can kick Back & will back fire . Threw Intake & Exhaust. So far Have not seen some un answered questions , One being What type of ignition switch Key on dash or in the steering column. & what style starter . Might be minor to others but it's part of the diagnostics!! Like others Have said Most Pre Made Off shelf & cable clamp / end are Junk Not big enough in ga wire size .
I'll have to differ on the battery cable size problem. This engine has 7000 miles on it and the cables worked just fine for that period. They don't shrink with age. You may possibly have corrosion in a connection. The voltage drop across 24" of 4 gauge wire carrying 150 amps is 0.0745v. The voltage drop across 24" of 1 gauge wire carrying 150 amps is 0.0372v. Another possibility is that the contacts in your starter solenoid are faulty and need repair with a kit like this one. ACDelco Professional D987A Starter Solenoid Repair Kit
24 inch with 150 amp draw Not that hard out of spec between 1ga & 4 ga ,,, How about 8 foot with 3-4 sec draw ? How much loss then ,, just asking I run 1 ga my be 2 ga 10 foot Being a T , battery more likely in the rear or father then 24 inches , Solenoid contacts repair kit , A few of us have question what style starter Op has, Do not recall that the question being answered.
The resistance of copper wire is generally specified in ohms/1000' @20C. The voltage drop across an 8' section would be four times that of a 2' section, in this case 0.298v @150A for a 4-gauge wire and 0.1488v @150A for a 1-gauge cable. The duration of the current has little effect. Power = volts times amps, so 150 amps with a 0.3v drop is 45 watts, about 6 watts per foot of cable. That would barely warm the wire in the short period of cranking. If you look at OEM rear mounted batteries, like BMW, Volvo, Chrysler etc, they use a short, small gauge ground cable that runs directly to the frame, and a larger gauge cable that runs forward to the engine. I use BMW cables in my rear-mounted batteries. I used to get them for $6 at Pick and Pull until they got wise to the length. If this is a GM engine the chances of having a starter-mounted solenoid are very high.
OK. A lot of questions. I'll try to answer. The car has 12 years and 35K trouble free miles with this electrical system. It's my daily. Engine only has 7K on it. Battery is located behind the passenger seat. Odyssey PC680. 2 years old. (See note) Grounded to frame with 6" long #1 welding cable. Homemade with soldered fittings with heat shrink protection. Positive cable is the same #1 cable 5 feet long. Engine ground is the same #1, 10" long. Starter is the standard old chevy with solenoid on top. I installed a new starter last night. All grounds and battery cables were disassembled and connections shined to bright metal last night. Ignition is Pertronix Flamethrower. New at engine rebuild 7K miles ago. Mechanical advance is free and working properly. Checked timing last night. 16 initial with 18 mechanical + 14 vacuum. Never seems to vary. Ignition switch is GM type from Speedway in the dash. Alternator checked out at 14.59 volts. Engine running volts is 13.6 volts at volt meter. Car is running and starting. Can't reproduce the non-start. Not much else I can do until it does it again. I will take the battery for a load test though. Jumper cables and remote starter are in the trunk. Just in case! It's just doubly damned embarrassing when you have to work on your homebuilt hotrod out in public Thanks guys. NOTE: This battery is meant for a large Harley. AGM. It is 3"x7"x7". Very small and mounted on its side. This is my 3rd one. Each lasted about 5 years. I keep the motor tuned for quick starts and haven't had any problems with the battery not being sufficient. Even in the extreme cold.
@jaw22w If all connections you feel are good, If it does it again And you changed with new starter & solenoid , I would look @ Key switch, This Happen even on Lawmower tractors , Many newer ignition switch are just junk, "" Purchase name brand" Or Old NOS , even a junkyard one. But more likely the problem was the contacts inside the solenoid And the contact studs on the inside Black piece both will get burnt spots & warp , Not a flat contact Old Starter No sign of Oil Soaked?
Would be interesting to disassemble the old starter . Perhaps you'd discover the cause of failure , only takes a bit of time ...
Although your issue with starting is not exactly like the one I had I'll throw this in just for my two cents. It's probably not the same problem I had. I had an ongoing problem with slow cranking after warm up. One day I pulled into home Depot in my 49 shoebox coupe with a 383 stroker and an old fella walked up and was interested in the car so I gave him the standard bragging... As I went to start it up and it was barely cranking he said "sounds like your starter is binding on the flex plate gear". Of course I initially thought that's impossible because I was careful in positioning the starter. However I did drive home and jack it up and crawl under there and look and damned if he wasn't absolutely correct. Here's why. When I installed the mock-up block while building the S10/shoebox/jag rear end frame, I thought that the engine looked as if it was too high. The motor mounts I had had two different mounting height holes so I lowered it to the lowest hole. Now back to my undercar inspection: by lowering the engine about 2 inches , one corner of the starter ended up about an eighth of an inch from the S-10 upper control arm pivot point. Although the starter was not touching the control arm, there was a little shiny spot. About 1 minute with the angle grinder on that little edge/corner corrected the issue. When cold, the diameter of the flex plate is smaller than it is when it's hot. Engine torque and maybe upper arm movement bumped the starter toward the flex plate. Whew.
LOL! Yeah, right now the starter is in the new starter's box marked ?????? I probably ought to figure out what's wrong, if anything. Storage space is getting pretty valuable,
I wonder why there is such a disparity between the alternator output voltage and your voltmeter sensing point? You're dropping a full volt across that wiring.
Good question. All I know about that circuit is that there is a wire that comes out the end that says VOLT METER on it about every foot or so.
When strange things like this happen & you Turn / fix , work on your own This is how you end up with Multiple tools and equipment , so you can verify, What ga wire from stud on back of alternator to starter , Charge wire . Should be @ least #10 ,ga Some require #6 ga On one of my combo I was using Red Top Ultima batt Im EFI , Electric pump MSD , Electric fan... 100 amp alternator, in my application unable to put a one 140-150 amp. No Radio , When E Fan kicks on , fan itself pulls over 50 A, @ idle I @ time could watch The Volts go from 14.5 slowly to 12:2 V That when I started researching batteries and reserve @ what amp pre Hour , Switched to Yellow top More reserve and amps per hour, Switch from Yellow to a Lithium with A reserve of 160 mints @ 95 amps hr.
Wire from ALT to starter is at least 10 ga. It looks bigger. Then my harness connects to the same starter post along with the + battery cable. I lose that circuit from there.
The charge wire to the battery should be large enough to re-charge the battery and provide enough current to the functions needed to start the engine, like ignition, starter solenoid and fuel pump. 10 gauge is plenty large. Once the engine is running, the highest voltage point in the system is the alternator output, and all your electric devices should be powered from this point. The battery at this point is just another load on your alternator. I use a short length of 6-gauge wire to a junction box, and all power is distributed from there. That way I get full alternator voltage applied to my devices. Power is voltage squared times resistance. 14.6v applied to a circuit will provide 15% more power than 13.6v applied to the same circuit.
@jaw22w Go to Power Masters website and you can read all about requirements wire ga and alternator , starter sizes or another Name brand manufacturer like Denso
When you say “volt meter” are you measuring with an actual meter, or relying on the gauge? Don’t be like me and replace an alternator because my in dash volt meter stayed a tad over 12volts running. Changed the alternator, same thing. Grabbed my meter, 14.-whatever it was. Faulty dash meter.
Most aftermarket volt meters will read a little low. It's fed by small wires as it is, not like the monsters to an amp gauge. You're over 12, it's all good. I'm gonna stick with my ideas. Or maybe a check/raise here, you said Pertronix. Yeah, anomaly. You didn't say, how hot was it that day? Techy stuff hates heat. Just sayin...
When I was a kid and messing with old used up junk, I would usually end up doing my $0 starter "rebuild". 1. take the solenoid off the starter and dissassemble. Turn the power stud 180 degrees to get a fresh surface for the contact with the washer. Dissassemble the washer/spring and turn the washer around for a fresh contact surface for the power stud, reassemble solenoid. 2. dissassemble the starter and wash the commutator and case with gasoline to get the carbon dust and DRIED grease out, especially from the commutator shaft and bushings. use a broken hacksaw blade to undercut the mica(s) between the coppers on the armature. Use a mill bastard file to manually round the armature and remove the low areas where the copper was worn down from the brushes (no lathe required for a serviceable result). Usually the brushes were re-usable (this is the $0 maintenance). Regrease the starter motor bushings with high quality grease. Reassemble all and reinstall. The usual result was an amazingly powerful and fast-running starter, for $0 and about an hours worth of easy work.
As you said, next step is a load test on the battery. NAPA has done it for me if I carry the battery in. Autozone was able to come out and test it in the vehicle.
An aftermarket voltmeter with a D'Arsonval meter movement, the most common of electric meter movements, should require about one milliamp to operate, and a small wire is very sufficient. A digital voltmeter requires much less current.
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