Won't crank

Went to the bank today and after cashing in a deposit my 85 chevy 1/2 ton wouldn't start. Won't even crank. I got out to check for loose battery ends and rechecked the dash guage but to no avail. Still showing 8 volt's. I called a buddy to go get the trailer but my buddy had borrowed it and took it out of state to buy a car he found super cheap. I called my older brother and caught a ride and we took it the battery to the local shop for load testing. It graphed at 1026 amps for 22 seconds. The battery is rated at 1000. I like big battery's. You can start anything with this battery except this truck!. Anyway, after checking head light's and dome light and dash guages and light's I determined it has to be the starter ate it self. I bought a new one at the local part's house and they gave me the wrong one(figures). While I had the old starter out I hooked up the jumper cables and the starter ran well. So I bolted ot back up and I still have the same problem. I replaced the ignition switch(it needed one anyway) when I could only get 8 volts at the switch but still had twelve at the battery. That did no good. I traced twelve volts from the battery to the starter solenoid where it bolted to the solenoid And show twelve volt's there but only 8 when the key is on. Could the starter solenoid be partially shorting to ground and not allowing twelve volt's the starter motor? Does this theory make sense? Do you think the starter worked while bench testing because the voltage was forced to follow the correct path rather than find ground through the block? I had the red jumper from battery POS to big terminal at solenoid the black lead to the bearing support at the rear of the motor. Opinions on needed!

Thanks

Well, first off, if it's a 1000cc batt, the load test should be ran @ 1/2 the cc rating, or,500 amps for 15 secs, w/ volt drop of no more than 10.2 volts. Did you check the small s term on the solenoid for juice? A shorted cell in the batt may not show on a load test, and could prevent jump starting unless it's disconnected! HTH Mike

Load test showed the battery to remain at 11.5 Volt's for 15 seconds at 500 amp draw. Well within spec. If the battery were used up, then jump starting with a known good battery would have allowed cranking. The problem is with the key on the battery will show twelve volt's but only eight at the solenoid. A short in the wire does not exist according to continuity testing from the starter to the battery terminal. I only left to believe the starter solenoid has shorted and leaking 4 volt's back to the battery instead of forcing the current through the starter motor. 8 Volts is not enough to energize the solenoid.

When the solenoid is energized, it pulls the plunger back, forcing the copper washer against both large terminals inside the solenoid cap, I don't see any way the solenoid can cause a voltage drop in the pos cable? Were you using the solenoid to check the starter off the truck? Yes, 8 is not enough, that is way too much drop in the cable, could the ends be corroded?

So you are blaming the battery even though it had been load tested good at the part's house. Correct?

I am very aware of the starter's operation for I have rebuilt many in my life time. I can't really see the problem described above happening either but I'm getting really frustrated with it and probably not thinking striaght. I got a big race to attend tomorrow and the truck it sitting in the banks parking lot. I have to leave in the morning and need to get it out a there.

Might be your ignition switch, try jumping the solenoid with a screwdriver to see if the switch is at fault.

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Outlawed tunes from outlawed pipes

You stated the batt checked out at 1026 amps for 22 sec's, and after you corrected the test readings I suggested the cable shouldn't have a 4 volt drop, the problem has to be the cable or ends! You haven't stated which terminal has 8 volts, I assumed the Batt term? Or is it the start term?

Chuck, I changed ingnition switches already.

Wrencher, I measured 8 volt's with the key on at the big terminal at the starter. The same terminal the batt. cable is attached to. The same terminal had 12 volt's with the key off. If the terminal or cable had a high amount of resistance than it would have shown 8 volt's with the key off or on. I'm not really trusting the part's house guy with his battery tool at this point. I wonder if he would let me use it.

I'm gonna assume the voltage at the batt w/ key on is also 8? Just a guess, but, it sounds like you have 12 volt reading @ the battery until the key puts a load on and the actual voltage drops to 8 volts, which sounds like the battery is defective, I did reply, I've seen batt's with shorted cells that would not jump, and would pass a load test!

I just came from testing the battery at another part's house and their machine tested bad but the smaller one would test good. Neither one of their machines would give an actual voltage/ amp draw however. I have three more battery's at home.( I'm not there right now). If the battery where indeed bad but would not jump, yet a small load from their small machine said it was bad but the larger load tested okay makes absolutely no sense whatsoever! I'm normally a man or science and reason with a mind for analyzing and these things drive me crazy!

We'll try another battery and see what happens I guess.

UPDATE!!

Changed battery cable and ends, New battery and starter motor and different ingnition switch, checked all fuse and pulled one at a time to see which circuit may be shorting out, Disconnected alernator and electric fan as well as heater blower motor and A/C compressor. All wires under the hood were wiggled and inspected as well as wipper motor and headlights, Bulk head was visually inspected. Still no change. The only change has been ten volt's at he starter soleniod where as before the was eight. Still no crank or light's or flashers or anything electrical. I'm out of idea's and patience if anybody no's anything I'll try it.

This should probably be moved to the electrical board by now.

pull the oil cap off and see if it looks like milk in there. i had a car do the same thing. sometimes it would start sometimes it wouldnt. it got worse and worse so i got a new starter and nothing. the crank turned by hand but upon further inspection the head gasket was blown.... and had just enough friction to keep the starter from turning it over.

Sounds like you have a ground problem. Disconnect the ground at the batt. put the red lead from the meter on the pos. post and the black lead on the disconnected cable end. Is there a ground between the body and eng. Where is the other end of the ground .Don't just check the batt. ends of the cables.

Johnson, Although you may have already checked these, I thought I`d ask have you checked the fusible links? One way would be to check the voltage before the link and after it, if it`s lower you found the problem.

It's never fun to call youself an idiot but I guess stupid is what stupid does.

Friday night I unloaded the race car and loaded my truck with a buddy's help. After we get it home, my buddy standing there looking at the batt and say's "Hey, hand me a wrench". He removed the battery cable end and cleaned the area where the wire enters the termanal end. That's all it was, really!!
I can't believe I missed that, I even replaced them to ensure it wasn't the problem! Can't believe I overlooked this so simple thing. Go ahead, let loose, I deserve it.