When I purchased my 67 standard 302-AOD I started with a slow crank situation. Anytime the car was warm, it was very hard to crank. I replaced the battery, battery cables and starter cables, and I was good for a little while. Six months later, I’m back to slow cranking.
If I turn the key and hold it, the slow cranking goes to no cranking and the ground strap from the negative battery terminal to the body starts smoking.
I pulled the battery, checked all my connections, put it back in and tightened everything up – it started right away. I turned it on and off about three times in a row, and I was right back to the slow crank no start situation.
I have a ground running to the engine block and to the frame. All cables are new. Battery has good charge and alternator is charging well whenever the car does start.
It always starts after it has sat overnight, but the length of time it takes to start again after a drive varies.
After checking everything again, I finally decided to pull the starter. That’s when I found the terminal post for the starter cable was stripped out. Apparently my starter cable connection was always loose.
I added a couple washers, tightened it back up, and all my troubles are gone. Guess I’m changing out the starter anyway, but not for the reason I thought.
I have had a slow-crank issue with two starters on Jeeps. They behaved very much like what you experienced – first crank wasn’t too bad, after that it slowed down pretty quickly.
The first one I had the starter checked before we left for vacation and it tested out okay because with no load on it – it actually took LESS amps to spin than the one that had the full winding working. I replaced the battery mid trip and it wouldn’t restart 50 miles from our destination – at 11pm. Fortunately we were meeting family who came and picked us up and I got to change the starter in the gas station lot the next day.
The second one I figured out before it left us stranded, but not after replacing the battery a couple of times in a few years as it wasn’t really the primary vehicle so it didn’t get driven to be able to diagnose as not just an old battery.
Glad yours was much simpler, but relaying my experiences to hopefully help others.
Edit: cleared up some wording around the vacation to make it more clear.
