I have a freshly built engine that is outside of the car on a wooden dolly. I want to test a few things, and build up oil pressure before doing a break-in run, but the starter is not cooperating. The engine turns over easily by hand with the spark plugs in. The new gear reduction/ hi torque mini starter is correctly matched to the flywheel. Brand new, fully charged Optima with 910 cranking amps. Positive to the big terminal, negative to the starter body and bellhousing When I apply power, the engine turns slowly, pauses, turns a little more, pauses, turns a little more, but not anywhere near a full rotation or fast enough to start. The jumper cables get hot, like the ground is bad, but it's connected straight to the clean starter and a clean bell. New jumper cables, too, with clean contact points. I removed the starter and it works fine on the bench. The flange to flywheel depth is correct and the starter gear extends about the right amount and seems to be engaging with the flywheel fully. What should I check next? It seems like it's not getting enough juice, bad ground or the starter is weak.
Agree with the above... Use the proper sized cables. I'd bet you have inexpensive jumper cables. Maybe 4 or 3 gauge, both positive and negative. Both the starter needs, and the battery has more power than small cables can handle. The "hot" cable is a BIG clue !! "1", gauge if the battery is close (short cable) to the starter. "00", if it's 5ft (long cable) or further away. Mike
Most any vehicle from the factory comes equipped with 4 gauge cables , many jumper cables are lucky to be 10 gauge .
As others have said, if the cables are getting hot they are too small for the load. You can verify this with a voltmeter. Crank the engine and measure the battery voltage. It should be above 9.6 or you may have battery problems. Next, crank the engine again and measure the voltage at the starter positive terminal. It should be within 0.5 of the voltage measured in the first step. If the battery voltage measured at 10.5 volts while cranking, the cranking voltage at the starter positive terminal must be at least 10.0 volts. If the drop in voltage more than 0.5 volts, your cables are too small (gauge). Last step is to measure the voltage between the starter case and the battery negative post while cranking. It should never be above 0.1 volts. I expect you will see over 0.5 volts drop on the positive and over 0.1 volts drop on the negative.
Also, don't turn the motor over to build oil pressure, use a primer rod and drill motor. Turning the engine over just wipes off all the camshaft lube if it has any on it. If the camshaft was installed with a liquid type assembly lube, it's already in the oil pan.
I tried basically the same thing on an ot car yesterday. Car had a 7 year old stone dead battery in it that wouldn't take a charge and my hot battery and cheapie cables wouldn't get it to crank but would let me open the rear hatch with the electric switch and start my hunt for the well hidden battery.
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