1965 L75 starter won't crank without jump or boost

[Mark W.]

My 65 L75 coupe will not crank over without a jump. It is a top flight car with everything new or restored done by myself. Engine wiring harness is new. Battery is brand new and fires up my 60 perfectly so its not the correct battery. Starter motor is rebuilt and tested. When I go to start it sometimes it will crank over. Mostly not. With a jump it turns over every time. Cant be the neutral safety switch or it would never turn over. The under dash wiring harness is original and the ballast resister could be original. California car with many original parts still including ignition (I think. Have had car 32 years. 69k miles) The ballast resister gets very warm but not real bad. My battery is grounded to the engine block. Car has original AC. I have a NOS ignition in the box I could put in but thinking its not the problem. When I go to turn it over I hear a faint click...just one. Then with a jump it turns over very fast. What am I missing?? Are there any grounds under the dash I need to check? What should I be checking. Any help or ideas greatly appreciated. Thanks

[Edward J.]

Re: 1965 L75 starter won't crank without jump or boost

Mark, if it starts with a jump the only thing that comes to mind is the battery cable ends maybe dirty between the battery post and cable ends. Taking a jump really verifies all the circuits from ignition switch to starter.

[Mark W.]

Re: 1965 L75 starter won't crank without jump or boost

Thanks for the reply Edward. I just checked the battery cable ends and I had already cleaned them with a battery cleaning tool. The cables are original style squeeze on and they are on there tight enough that I cant twist them. I already took off the green knobbed battery cutoff to eliminate it being the problem. I just tried it again after checking the cable ends and cleaning them again and no go. I just hooked up a 40A charger and she cranks over nicely. Maybe I should try cable ends that tighten by nut. I will probably try that tomorrow but the ones I have now seem very tight and are definitely making a very clean contact. Thanks again.

[Leif A.]

Re: 1965 L75 starter won't crank without jump or boost

Could, also, be a contact points (brass wheel) in the solenoid that's carboned up. The additional surge from the 40A jump box may be enough to arc thru the crud on the contact point wheel. How old is the starter solenoid?? You said you have cleaned up and secured the battery cables at the battery but have you checked all the connections at the starter and solenoid?

[Joe R.]

Re: 1965 L75 starter won't crank without jump or boost

Hi Mark,

It sounds like the problem has to be either the battery or the connections to it. When you jump start the car, do you hook up right at the battery? That would eliminate everything else. Maybe the 65 needs more current than the 60 to start. I would suggest taking the battery to your local auto parts store to have it tested.

Joe

[Edward J.]

Re: 1965 L75 starter won't crank without jump or boost

Mark, the next step is to take a volt meter and see what the voltage is at the battery generally a full charged battery is 12.66 volts, the check the voltage at the starter solenoid when cranking to see what happens. this is called a voltage drop see what the voltage drops to and report back. another thing is to make sure the engine block is grounded to the frame(motor mounts, battery cable to starter or bellhousing etc.) and that there is no painted surfaces that may imped the connection to ground Corvette's can only come to life with good grounding circuits, being a fiberglass body.

[James G.]

Re: 1965 L75 starter won't crank without jump or boost

Mark, the next step is to take a volt meter and see what the voltage is at the battery generally a full charged battery is 12.66 volts, the check the voltage at the starter solenoid when cranking to see what happens. this is called a voltage drop see what the voltage drops to and report back. another thing is to make sure the engine block is grounded to the frame(motor mounts, battery cable to starter or bellhousing etc.) and that there is no painted surfaces that may imped the connection to ground Corvette's can only come to life with good grounding circuits, being a fiberglass body.

PERFECT answer. A good repair shop will have a AVR test machine that will check the complete charging and starting circuit. Start the car, and drive it to your local garage. And have them check the complete system. You may to even have to do a ohm reading on each cable to see how the condition is ''electrically'' not just ''NCRS wise''. This check and their expertise will answer your question.

[Mark W.]

Re: 1965 L75 starter won't crank without jump or boost

My 65 L75 coupe will not crank over without a jump. It is a top flight car with everything new or restored done by myself. Engine wiring harness is new. Battery is brand new and fires up my 60 perfectly so its not the correct battery. Starter motor is rebuilt and tested. When I go to start it sometimes it will crank over. Mostly not. With a jump it turns over every time. Cant be the neutral safety switch or it would never turn over. The under dash wiring harness is original and the ballast resister could be original. California car with many original parts still including ignition (I think. Have had car 32 years. 69k miles) The ballast resister gets very warm but not real bad. My battery is grounded to the engine block. Car has original AC. I have a NOS ignition in the box I could put in but thinking its not the problem. When I go to turn it over I hear a faint click...just one. Then with a jump it turns over very fast. What am I missing?? Are there any grounds under the dash I need to check? What should I be checking. Any help or ideas greatly appreciated. Thanks

I would like to Thank everyone for the excellent advice. I had the starter, solenoid and battery checked and they are good. My grounds are all good and cables are newer repros and very clean. I made a mistake with the wiring harness. The front lamp is a new repro and the engine harness is original and looks great but is very stiff. I ordered a new harness and I'm thinking I must have a weak spot in it. Hoping I am right and will let everyone know if its the problem. If not I will take it to a shop and have it put on a AVR test machine. Not doable now because I'm a New Yorker and there is snow on the ground. Thanks again. Mark