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Persistent problem on my 115C: with battery fully charged and easy starting when engine cold, I notice very slow cranking when engine is fully warmed up. I am not sure how to read this symptom - is it the starter solenoid not functioning well when hot, the starter itself, or does it just take more juice to turn over a hot engine? Is there a way to diagnose the issue short of buying replacement parts until it goes away?

By all means do not throw money, parts and time at the car to fix it, diagnose it first.

I'd suggest checking the voltage at the battery terminals when cold and then at the starter terminals when trying to start it cold (disconnect coil wire).


Then repeat when hot to determine if you have an excessive voltage drop when hot. If there is,,next determine exactly where the drop is with a voltmeter. If found, clean the connections and try again.


Let us know what you find.

Thanks
James From
Kanter Auto Products

Classic symptoms:

1. Undersize (12-volt) battery cables.
2. Loose or corroded battery cable connections.
3. Starter motor due for service.

Thanks for the tips, guys. And for the authorization to buy a volt meter.

In the meantime, I looked at a bunch of posts related to the hot cranking topic and other potential culprits seem to be the armature bushings and coil.

It will take me a while to get back to this but I will update the post when I figure it out.

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.

Thanks Howard. I have to confess to being virtually illiterate when it comes to electronics. There are hundreds of meters listed on Amazon. It's not clear whether the ones with amp meters measure DC. Would you be able to suggest one?

Perhaps someone in the Seattle area could loan you a different starter to see if the issue is the starter. Also, has the motor been very recently reconditioned as some motors get quite tight with new rings/ bore cross hatching, etc, until the pistons and rings have bedded in?

Just a thought. Peter Toet

Thanks for the suggestion Peter. Will try it out.
Jake

Quote:

There are indeed a plethora of meters to choose going from cheap to professional quality. Here is a small sampling and any of these would be a good choice for the home auto guy. I have the Mastech because it was most suitable price and feature wise when I bought it a couple of years ago. Since then Amazon is carrying more brands with different features.

There are several priced in the Synerky range of $30 and the BTMeter at $45 has a temperature probe and a couple of other features which might come in handy. That one might be my choice today. Kind of depends on what you want to pay so look thru them all. They can all read DC volts but many clamp ons can only read AC current. If you find one with different features or a price you like just make sure the specs say the meter is capable of reading a DC current of at least 400 amps.

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Normally, I can find OO size battery cables at Napa and also the terminals that can be soldered on. OO cables work great. All your connections should be clean and snug and your six volt system will work just fine. Ernie in Arizona