Re: 1937 115C slow crank when engine warm - starter, solenoid?

Posted by HH56 On 2018/7/6 16:00:29

Make sure the battery is in good condition. A hot battery loses efficiency and if you have a marginal cell or the battery is getting ready to fail it will show up when hot. Perhaps a load test which is often done free at a parts store or garage is worth looking into.

Also make sure your battery cables are large enough. If original then OK as long as the terminals are clean and tight and no internal corrosion in the cable but if replacements, they should be a 0 gauge. 00 gauge if it is a long distance between the battery and starter. The typical cable sold in parts stores today -- even though some are rated or claim to be for 6v are generally too small and result in a voltage drop when trying to operate a starter trying to turn an engine in which parts may have expanded and become a bit tighter.

Rather than buying just a voltmeter I would spring for one with a clamp on ammeter that can read DC amps. Amazon has several that are fairly inexpensive and can read up to 600 AC or DC amps. A clamp on ammeter would be a quick way to test if the starter is losing efficiency or is dragging when hot. If the current draw is radically different cold vs hot that would be a good indication the starter might stand a look see.