1992 Cadillac Deville Car starting problem

Removing a generator or a starter from the engine is the worst and least effective way to test them. You got that advice from a parts salesman, not a mechanic. Test benches have up to one horsepower motors to run generators. They can not possibly run them wide open to test them for maximum current output. That takes from five to eight horsepower, and that test is especially important on the very poorly-designed GM generators. They develop huge voltage spikes that can destroy its internal diodes and voltage regulator. With one defective diode of the six, you will only get exactly one third of the unit's rated current, and that is not enough to run the entire electrical system under all conditions. The battery will have to make up the difference until it slowly runs down over hours or days. You need a professional load tester with the generator being run by the car's engine to test for maximum output current and "ripple" voltage, both indicators of a bad diode. A generator with a bad diode will still produce some current, and output voltage will be close to correct, so the unit will falsely appear to be good on a test bench.

Off the engine a starter spinning freely will draw less than 50 amps. Any tired old starter can do that. You need to test it under load when it's trying to crank the engine. During that test Chrysler starters will draw around 150 amps. Most others will draw around 200 amps, ... Even more on older V-8 engines.

You are getting no response at all from the starter. A weak battery, or a battery that is run down due to a defective generator will not cause that. Those will cause slow cranking or a rapid clicking / buzzing noise. Starting normally after an hour and a half proves the battery is still okay. It didn't magically fix itself. And the generator is not the cause of this issue because it isn't even in the picture yet until after the engine is running.

Starters CAN be intermittent but that is not real common and it doesn't stay in the condition for long before it fails completely. Your mechanic can perform one starter test on the car to see how much current it draws, but the results will be of no use to you. We know it's not dragging and drawing excessive current because it does crank the engine normally when the system works. It is more likely there is an intermittent problem in the control circuit, meaning the ignition switch, starter relay, and neutral safety switch. That is a low-current circuit but it has more parts than the high-current starter circuit, and it is responsible for a lot more problems. Starter testers do not test anything in that low-current circuit.

There's two relatively common things you can try yourself. First try cranking the engine with the transmission shifted to "neutral" or after shifting out of and back into "park". If that works, suspect the neutral safety switch. Next, follow the smaller positive battery wire to the under-hood fuse box and be sure that connection is clean and tight. Those work lose on a lot of car models and cause intermittently dead electrical systems.

Any further testing has to be done while the problem is occurring. As long as the entire starter system is dead, (not just cranking too slowly), and everything else is working, the system can be broken down into four parts, and each one has a test point at the starter relay socket. If you find anything else is also dead, like any lights, the radio, power windows, etc, you don't have a starter system problem. You have some other electrical problem that includes the starter system. Spending time in the starter circuit in that case is a waste of time.

You need a professional load tester to test starters. They use an inductive pickup probe to measure current flow, and they measure what the battery voltage gets drawn down to during cranking.

Your symptoms are a little different and suggest the field coils in the starter may be warping causing the armature to drag. That can be identified by measuring starter current with a load tester with an inductive pickup. Instead of the normal 150 amps, you'll find around 200 or more. One of the brushes could be worn too but that's harder to identify. The starter motor is actually two motors in one package. When one of the four brushes fails to make contact, only half of the motor will work, and that's not enough to crank the engine at the normal speed. Current flow will be half of normal, but because of the low cranking speed, "back EMF" will be reduced which opposes current flow, so the actual flow will go up and appear to be normal.

If that doesn't pan out, start a new question. When you piggyback on a different one it will only be seen by the three of us. One of the other experts may know exactly what is wrong but they will never see your post. That does a disservice to you.

You can start with cleaning and tightening the connections on the larger positive and negative battery cables, but without voltage measurements it's like asking your doctor why you're in pain but you won't let him do any tests. I need voltage readings to analyze. Beyond that, the most likely suspect is worn brushes inside the starter motor. When one doesn't make good contact, you only have half a starter. Current flow, if you had access to a load tester, would be near normal, but the voltage at the starter terminal would be higher than normal.

The way I would start is by measuring the voltage on the larger starter terminal when the engine is cold and the starter is working properly. It must be higher than 9.6 volts. Typically you'll find around 10.5 to 11.0 volts. Now you have a reference to compare to the reading when it's cranking too slowly. If the voltage then is higher, the starter isn't drawing enough current and loading down the battery. If the voltage is lower, the starter is drawing more current. That is usually due to the field coils warping when they're warm. That shouldn't be an issue with your starter. GM went away from field coils in favor of permanent magnets. If one of those breaks loose, the starter will never work properly at any time.

"Spent $300.00" doesn't help. You have to list what was tested, the results, and what has been done so far. You're better off starting a new question so all the experts can see it and have a chance to respond. Be sure to include the engine size and the exact symptoms. I've already listed the most likely causes of this problem based on the information I had.