random cranking

[govproperty]

I am having a problem getting the car to crank consistently. When it does it starts and runs fine. I moved that battery from the back of the car to the front subframe to eliminate some possibility of voltage drops causing trouble. The battery is at 12v and my charger says that it is still good. I also tried it with another battery and got the same results. I replaced the starter just to be sure and it didn't change. I am getting 6v to the start solenoid when the key is in the start position. If I remove the wire and check for voltage with the key in the start position I get 12v. I don't know if a 6v drop is normal. The solenoid sounds like it is moving however the engine won't crank all the time. Also, I removed that starter and wired it up but without the engagement of the flywheel and I could not duplicate it. I also, could not duplicate it if I used a handheld remote start switch to activate the solenoid. My train of thought was that there might not be enough amperage in the solenoid wiring to pull the solenoid all the way in or I have another bad starter. I don't feel good about driving it anywhere since I don't know if I could get it started once it is there. I am open to any suggestions.

 

[Rsawd95dsm]

What gauge wire did you use?

 

[govproperty]

I have the same 1/0 welding wire that I was using for the battery relocation except it is only about 2 ft long. I grounded the negative to the transmission and the positive is connected straight to the starter. The alternator is not hooked up at the moment. I didn't notice any voltage drop in the but I might throw something on the temporary just to rule them out.

 

[wrencher]

Your getting 6 volts @ the starter solenoid positive lug cranking, is that measured from the negative battery terminal?
Either way that is too low OR high depending on how your testing from - or +.

Have you tested for voltage drops also?
Testing for voltage the same way while cranking, go from the positive battery terminal to the positive lug of the starter while cranking.
Also test from the negative battery terminal to the engine block/transmission while cranking.

The rule of thumb here is no more than .50 volts.
Experience over the years for me is over .40 is really high on a 200 amp cranking circuit like our cars.
You can also test the starter mounting body/ear to the transmission in case you have some funky problems.
But if you have a voltage drop problem you'll find it testing in that manner.
Any leg that has excessive voltage drop while testing is your culprit.

*But* If you find very high voltage drop in the whole circuit, positive & negative. That & the amount of measured voltage is near the same + & - in drop testing, you have excessive amperage draw on the starter circuit.
Like a bad starter or an engine problem.

 

[govproperty]

I think I found the problem. I could only trace the volatge drop on the starter solenoid side. I found that this connection had a bit of corrosion in it and once I repaired it the car did not seem to have a problem starting on demand. Thanks, for all the help.

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