'41 Cadillac Series 62: Starter w/ Apparent Mechanical Problem

[hloree]

Dear CLC - I recently joined the club, so this is my 1st post. I own a 1941 Cadillac Series 62 Formal Sedan with custom coachwork by Derham. I need some help to resolve an apparent mechanical problem with the starter. The car is essentially original with ~ 100K miles, with an engine that was professionally rebuilt about 2 years ago. Recently, the starter has been cranking very slowly and the engine has been reluctant to start when cold or hot. I replaced the 6V battery and positive ground strap to the frame, ensuring good electrical connections, and noted some improvement. I recently performed a much-needed tune-up and confirmed proper timing and compression in all cylinders. Upon completion, the starter would not properly engage or turn. The voltages at every point up to and including the solenoid connections are almost 6 V.  I removed the starter and replaced it with a spare that had been professionally rebuilt and checked out OK on the bench; it spins fast with proper action of the Bendix drive. However, the new starter acts just like the old one: apparently jammed and unable to turn. Could there be some misalignment between the starter pinion and the flywheel ring gear that is causing all this? What is the next step to diagnose the problem? Thanks! - Howard Loree, Littleton, MA

[wheikkila]

My first thought is to remove the belts and then try to turn the engine over. Maybe you have a bad bearing in the fan or generator.
             Thanks Wayne

[Ohjai]

Howard, you said you replaced the negative ground strap.  What size did you use, one the size of a pencil, or one the size of your index finger?


If I 'm not mistaken, the ground wire goes from the battery positive terminal to a junction on the frame, then another wire goes to the engine.  These are large cables, not like you find on modern cars,  Also check and make sure the connections are clean and tight.


Jim

[hloree]

Hi Wayne & Jim - Really appreciate your prompt responses. Engine turns over smoothly, even with belts engaged. Positive ground to frame is via a strap purchased from McVey's Cadillac, which has a generous cross-sectional area. - Cheers, Howard

[35-709]

Negative ground?  Is this not a Positive ground car?  It was when it was built.  Has it been changed for some reason?

[Ohjai]

Good catch 35-709, I corrected my post to read positive terminal.

[hloree]

I stand corrected. The car uses the original 6V + ground electrical system.

[Abe Lugo]

Get some custom fatter cables made.  I use battercablesusa.com 6volts need almost double thickness cables form what 12v cars use.  Change both battery cables.  Besides the ground straps. Also ground the engine to the frame.  I used 00 size on wife's 6 volt '33 and it has not starter spin issues.  We also got the optima 6volt battery.

[Daryl Chesterman]

The voltages at every point up to and including the solenoid connections are almost 6 V.

A fully charged 6 volt battery should read 6.3 to 6.4 volts.  I think you need to do some checking to see why you are not getting the full battery voltage to the solenoid.  You may have a bad cable from the battery to the solenoid.  If the cable has internal corrosion or broken strands, you can measure 6 volts, but the resistance will be high, and the bad cable will not supply enough amperage to allow the starter to crank.  Remember Ohm's Law: V =I/R.  Therefore I=V/R, and you can see that a high resistance provides less amperage.

Daryl Chesterman

[Bill Ingler #7799]

Howard: It is very important in slow cranking/starting engine to check that the engine is properly grounded to the frame. Remember the engine is supported 3 places by rubber mounts, each side at the front of the engine and at the rear of the transmission.
Check your right front frame/engine mount for a braided copper ground strap that goes around the rubber mount to ground the engine to the frame. I also put this type grounding strap under the left engine mount on my 41 as well as the 47. Check also to see if you have 2 small braded copper ground straps bolted to the firewall. The other end of these ground straps goes under the rear head bolts of the center row of cylinder head bolts. I also attached the battery ground cable directly to the bottom mounting bolt of the starter.  I made my own battery cables from double 00 rubber welding cable and use 6 volt Optima Batteries.    Bill