Here's the deal. Two new batteries, two alternators, two different starters, two different starter solenoids, new battery cables, and new voltage regulator.

My '68 F250 390 has recently received all of the aforementioned items. When cold it fires up like a dream, but after it gets to normal operating temp and is shut down, it is either really sluggish in restarting or will crank about a second or two and then quit. It sounds like a classic example of a dead battery or a stuck starter, but everything checks out. I've got 12v at the battery and around 15v from the alternator so the battery and charging systems are good. We've used a professional Sun electrical analyzer, put the system under loads and still can't pinpoint the problem. Let it sit and cool-down for a while and it fires right up like it does when cold (almost as easily as my Expedition). BTW the timing is set at 10 degrees BTC so it's not abnormally advanced.

I never have to worry about it restarting, it always does, the question is how long am I willing to wait? Is the starter just getting too hot (no headers here), sticking, and in need of a cool down period? Any ideas?

Thanks.

Jim

 

Could the timing be advanced too much?

 

Hi,

Sounds to me like the alternator output may not be making it back to the battery. You said there is 12V at the battery but 15 volts at the alternator, check to see if the wire is broken/open circuit. You should have the same (or very close) value at the alternator output as you do at the battery. My truck, when running, measures about 13.8 volts at the battery terminals. The same is measured at the output of the alternator, plus the voltage drop across the wiring. It seems like you have also changed almost everything except the wiring!

The hot VS cold motor thing may be a mis-leader. When the battery has a while to relax, the electrolite and plates in the battery will become "stronger", any be able to deliver more current to start the motor.

Just some ideas, hope this helps, let us know how you make out,

-Brents

 

Is the engine getting too hot? Does it kick back when warm?
I forgot if it's a stick. Could the clutch be dragging when it's warm? Just some thoughts.

1977 Ford F-100
400m/c6
280,000 miles
Stock on the outside
modified/rebuilt everything

 

Since it sounds like you have checked most everything out, check the wiring. If a wire is being subject to too much heat it will reduce the conductive properties. Have you repositioned any of the wires close to heat sources while you replaced the other components. You could try comparing the impedence of some of these wires when the truck is cold and hot. Just make sure you don't jump anything.

 

[font size="1" color="#FF0000"]LAST EDITED ON 11-May-01 AT 05:22 PM (EST)[/font][p]I would agree with brents. you should have the same voltage at the battery as the alt when running. Otherwise, the new starter may have something wrong with it that makes it drag.
Another thing, make sure you have a good ground both on the battery cable and through the starter. If this is a new engine, it could be assembled "tight", so when things internally are warmed up they get tighter. just a thought
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.

 

I would do what ever I could to keep the starter cool. I had the exact same problem when I had headers on my truck. Some starters didn't seem to mind the heat at all, while others needed to cool down for about two hours.

You might try to stretch an old sock around the starter and then wrap that with aluminum foil to insulate and reflect the heat. Having a heat shield between the exhaust and starter should help also.

 

Check the ground cable from the engine block to the body. If it is not getting good contact, it can cause some strange problems.

Nathan

 

Remember reading something about mud,dirt,grime holding in heat which can make a starter bitchy. Had a similar problem with one of my cars. Replaced the starter and in the process discovered that the wire going to the starter was missing a lot of it's insulation. Don't know if it was the starter or the wire but after I replaced both haven't had anymore problems.

 

All those ideas are good to check, especially the electrical connections. Might also replace the condenser in the distrib. They can cause problems with hot starts like yours and are relatively inexpensive.

 

Myself would also pull the wiring harness from inside cab to the coil, unplug inside cab and check, its a 3 wire harness that goes to coil, water and oil. And one time had the dist gear shear and was about a quarter turn off but would start good then hot would be would not start. And also new and rebuild starter are not alway as they seem. As you know in this world there are people that paint and clean them and return for there money back
GWB

 

Like the first post said. Check your timing! If it advanced to much,it won't crank the engine. Back it off some, and see if you still have the problem.

 

Thanks for the responses guys. As I said, the timing is set perfectly at 10° BTC. I have 10:1 compression, am running pump gas and don’t have any pre-detonation nor any after-run once I shut off the ignition. I should have been more specific in my original post…everything associated with the engine is new except some of the original wiring, that is in excellent shape. The more I think about the problem, the more I think it has something to do with the starter overheating, even though I don’t have headers. I will remove and replace (again) and see if this helps. I will also see about shielding the new starter to prevent excessive heat build-up. The guys at the auto parts store are stumped as well.

“And one time had the dist gear shear and was about a quarter turn off but would start good then hot would be would not start.”

GWB, what enables the engine to start with no problem when cold and then act abnormally when hot? In other words, why does the engine temperature affect timing?