QuestionQUESTION: We have a 1950 Ford F1 with a Flathead V8 that's been converted to 12 volts. We hear the starter turn but it won't turn over the engine. If we push it and pop the clutch to get it started it does start and runs well. It was starting ok a month ago. Any suggestions on what the problem could be and how to fix it. Thank you in advance.
ANSWER: Before I go off down the wrong road here, clarify for me what you mean by "won't turn over the engine".
Do you mean the starter spins at a very high RPM but doesn't actually crank the engine? If you don't know the answer to that, open the hood and watch the fan blades as you try to crank the engine. If the fan is turning, then the starter IS turning over the engine, and your problem is most likely something in the ignition system.
If the fan is not turning, the starter isn't engaging the ring gear, which is one common result of a 12 volt conversion - which is why I try to talk people out of this sort of modification. If this is your situation, your starter will have to be removed and rebuilt. If you have that done, be sure to tell the shop to make it compatible with a 12 volt system.
Dick
---------- FOLLOW-UP ----------
QUESTION: Thanks for the quick reply,the starter sounds as if it's spinning at a high RPM as you said but the fan blades are not moving. Is this something that comes and goes? because as I said before it was starting ok about a month ago.
AnswerOK< thanks for the reply. You are in the second category - your starter drive has failed, which is not surprising if it wasn't modified to deal with the 4X added power it puts out since the conversion to 12 volts. (Twice the voltage means 4X the energy input and output of the starter, which often fractures the drive gear teeth, either in the starter drive or on the ring gear).
The only cure is to have the damaged part replaced. If the damage is to the ring gear, it could be possible to jog the engine slightly by pushing it in gear so that the damaged place on the ring gear moves around the circle a short distance, and then perhaps the starter will find teeth to engage in when you try to start it - in which case is might start the engine once in a while, but basically, your problem won't be cured until you replace the damaged parts. The starter has to be taken off and examined, and also the ring gear has to be examined and perhaps replaced, if there are damaged teeth. This later operation requires removal of either the engine or the transmission to the car to repair it, although you can inspect the ring gear once the starter is removed.
As I said before, when you put the vehicle back together, be sure the starter is one that can cope with 12 volt power without busting teeth off the gears! This requires a major modification to the starter.
Your other possible course of action is to put the truck back to 6 volt positive ground operation, which is what Henry intended, and had served well for 60 years (including my own 1952 F2, by the way). You will still have to replace the starter drive gear and/or the ring gear, however, to get the vehicle so it will start again reliably (or else always park it on a hill).
Dick
