The Stovebolt Site Forums The Shop Area The Electrical Bay engine just died with loss of power

hi all, i know my truck is not standard 1950, sometimes i wish it was, but i was wondering if anyone could help me out here with a problem i have with my motor.
i have a 1971 350ci fitted with auto trans, i was out for a run the other day when all of a sudden the engine just died and would not restart. after towing the truck back home i discovered i have no spark at the plugs, i have a delco remy HEI distributor fitted, the type with the coil built in the cap. i have 12v going to the distributor but as i said no spark at the plugs. can anyone point me in the direction of a fix, would this problem be down to the distributor coil?
thanks in advance.
bill.

There are two main possibilities, the pickup coil that surrounds the distributor shaft, and the ignition module, the 4-pin electronic device mounted under the distributor cap. The pickup coil can be tested with a digital voltmeter. Unplug the 2-wire harness going from the pickup to the module, and attach the leads of an AC voltmeter to the wire terminals. Crank the engine, being careful not to snag the wires with the rotating distributor shaft. The voltage generated by the pickup coil should be about 1/2 to 1 volt AC as long as the shaft is turning. The module requires some dedicated test equipment that most shade tree mechanics don't have- - - -if the pickup coil is generating a signal, swapping the module should put you back on the road. Ignition coil failures on this system are extremely rare, so swapping the coil up inside the cap is usually not necessary. One other thing- - - -the very early design rotor buttons had a habit of burning a hole under the center connector and routing the high voltage spark to the center of the distributor shaft, but all of those rotors probably failed and got replaced many years ago.
Jerry

Hi jerry thanks for the advise, I was thinking of replacing all 3 but here I the uk would cost me £100 plus. I will try your test method and hole it is just the module.
Thanks again
Bill.

thanks jerry, i will give that a go.

bill.

well, i have got the motor running, thanks to jerrys advice. i bought all three parts but only replaced the module and the coil, i couldn`t work out how to remove the parts that sit above the pickup coil to install it,but hey all is well and i am back on the road again.
thanks again jerry for the advice and help you offered.

bill.

It's necessary to remove the drive gear, and slip the shaft out of the distributor housing to replace the pickup coil. They don't fail very often, and the cap-mounted ignition coils are very reliable, so it was probably only the module that caused the shutdown. Another chronic problem with HEI distributots is wear on the centrifugal advance parts under the rotor. A little high-temperature wheel bearing grease on the moving parts, particularly the pivot points, will prevent them from rusting and/or wearing out. Glad you're back on the road!
Jerry

jerry, would the problem i have with my alternator cause the module to fail? i get a strange int whirring noise from my alternator which makes the needle on my ammeter go up to full, when the noise stops the needle drops back down to where it should be.
its like the alternator is pushing out to much when this noise happens. i have been trying to find out about this now for a while.

Yes, that's a definite possibility. If you check the battery terminal voltage while the noise is happening, you will probably find that it's very high- - -15 volts or more. Solid-state electronic devices such as your ignition module really don't like voltage surges. Does your charging system have the old style alternator with the external regulator, or is it the 10-SI model with the regulator built into the alternator? If it's the early model, the points in the voltage regulator could be sticking, causing the alternator to go into full output without any regulation.
Jerry

hi jerry, there is no external regulator just the alternator. i will get the truck out of the garage later today and check the voltage at the batt terms.
would a replacement alternator cure the problem? someone mentioned that a short in my wiring might cause the alt to push out too much. i cant smell any electrical burning and the alternator might have been the cause for my fuses to keep blowing.
thanks again for your help jerry.

bill.

ok, this is how it is. this afternoon i done some testing using my digital volt meter, i connected the meter to the battery and was getting 13.4v with the engine running, when the whirring noise from my alternator started i was getting 16.7v at the battery and when the noise ceased it went back down to 13v.
my alternator seems to be wired up wierd, this is how it is wired. i have one wire going to the nut terminal on the rear of the alternator which goes round the engine bay and in to the loom over on the drivers side. there is a white connector with two wires coming from it, one red and one white this plugs into the side of the alternator. the red wire goes to the same nut terminal on the rear as the othe wire and the white is not connected but has some sort of device built in line on it.
i tested, while the engine was running,the two spade connectors in the alternator on the side where the red and white wires connect to using the white plug. on the spade which the red wire would connect to i got no volts and on the other which the white wire would connect i got 0.05v.
by this time the whirring noise coming from the alternator was constant and pumping 16v into the battery. i pulled the white plug out of the alternator, the noise stopped and has not returned and i was getting 12.5v at the battery.
does this make any sence, do i leave the white plug pulled out, what is this connection for? the device that is wired in line on the white wire has the following label attached and reads.... INGERSOL RAND 120403-025,V#18558,59732305 002.

i am now confused but at least the alternator isn`t cooking my brand new battery.

bill.

I had a long reply typed, and the server change the site was going through ate it. The problem is with the internal regulator in your alternator, not the wiring. What you have described wiring-wise seems to be correct. It's not a huge job to change the regulator, but it does require dismantling the alternator. The tricky part is getting the brushes back in- - - -there's a hole in the back of the housing for a short piece of stiff wire that keeps the brushes retracted while you put the rear housing back on. A rebuilt alternator is the quickest fix because you'll also get new bearings and other parts as well as a regulator. Good luck!
Jerry

Thanks for the info jerry it will prob be easier for me to buy a new altternator I doubt if I could get a rebuild kit over here quickly. Do you know if it would be ok for me to drive the truck with that plug out, the batt is still charging ok at a constant 12.5 v.

No, the battery is not being charged- - - -that's normal voltage for a fully-charged battery without any input from the alternator. Each cell produces an open-circuit voltage of 2.1 volts, for a total of 12.6. It takes a minimum of 13 volts to keep a battery charged, and 14 is better. Most regulators cut off the alternator output at 14.7-15 volts several times a second. If you run the engine for more than a few minutes, or use accessories such as the headlights, wipers, etc., the battery terminal voltage will drop very rapidly. Original-equipment batteries on US vehicles are required by federal regulations to be able to run a vehicle with a minimum of accessories operating for one tank of fuel before the engine dies due to lack of voltage. That's assuming the alternator stops charging when the battery is fully charged and is in good condition.
Jerry

Just fitted a new alt and all is well. Gettin 14v at batt everything is fine.thanks for all your help jerry.

Sounds good! "Keep on truckin'!"
Jerry