The starter motor on my 1937 Ruby struggles to turn the engine over when hot, but works fine when cold. It has not failed to start the engine so far, but turns the engine over so slowly that it barely manages to start at times.
The earth and supply cables are connected directly from the battery to the starter. I have cleaned and sanded the connections at battery and starter so that they bright metal and firmly bolted.
I guess the next step maybe to dismantle the starter. In this case, do any members have ideas on what I should be looking for as the cause ?
Regards
Graham.
Take the switch off the starter and make sure the connections inside the switch and on the starter body are clean (they often get coated in oil). If no improvement, the starter motor brushes might want renewing.
03-02-2022, 10:04 AM (This post was last modified: 03-02-2022, 10:05 AM by Ivor Hawkins.)
It is also worth checking that your battery is tip top with a proper load test.
The starter is a really simple piece of kit and a thorough overhaul is something you can do at home in a morning, if it is really knackered a lathe would be a great help. I brought mine back from the dead and it’s doing sterling service.
I'd be inclined to check the brushes first, and make sure they are free to move.
It's a long time ago now, but I seem to remember that part of the current path in the brush holders is via rivets. These can be mechanically tight, but get corrosion under their heads. With the high current drawn by the starter, the slightest extra resistance has a significant effect. I think I left the rivets in place but soldered a braided link in parallel.
The winding resistances will be maybe 10 or 15% higher when the starter is good and warm, which will also reduce the current slightly.
Ahaa, so winding resistance is higher when hot. Thanks for that info.
Is there anything else that could explain the poor performance when hot?
Regards
Graham.
Under the heading of starters it is perhaps the place to mention the lever switch. The lever should not be able to tilt excessively sideways. Can short and wedge and many of the 80 ampere hours then go as smoke before tools can be found to sort things out.
The burned fingers take longer to recover than does the battery.
To add to Bobs sage advise,
The brush cover can fitted in such a way that it can short to the copper terminal.
The insulation in the switch can break down with interesting results when the starter motor is covered in dirty oil.
I have had one catch fire due to this.
I always keep a fire putter outer in the car and it only took a couple of squirts and a quick disconnect of the battery to sort it.
I fitted a brand new contacter switch and all has been well since.
Thanks for all the advice. I am going to get the battery tested first. I use a smart battery charger which lately has reported "error " when completing the charging process. The operating instructions for the charger say that "error " indicates that the battery doesn't receive the full charge. This could mean that the battery may have a defect that is causing the hot start difficulty.
Regards
Graham.
07-02-2022, 09:25 PM (This post was last modified: 07-02-2022, 09:30 PM by Bob Culver.)
In case anyone is tempted, starter segments are not undrcut.
(Eons ago as a radio tech with a colleague visited a manned light house to check the radio beacon. (Boaties could find their way home or 180 deg away using a portable radio). The keeper, bored out of his scull, decided to renovate the power generator and undercut all the segments...putting it later out of action. He got all the tedious visitors to sign then claimed for the tea and biscuits! The keepr preferred unaccessible island stations. )
I have followed the advice in this thread and appear to have resolved the issue of my starter struggling to turn the engine over when hot.
First I had the battery load tested by a supplier of 6V batteries. He tested the battery on two different load test instruments and very positively said that the battery was fine. He had batteries of the correct size to replace mine but refused to sell me one because he felt that would be fraudulent.
The next step was stripping the starter. The brushes were made of a copper mixture and consequently the interior of the starter was coated with an oily film of copper dust. I washed out the oil and dust with leadfree petrol per Woodrow manual. The was some light rust on part of armature and on two poles. I sanded this off.
There didn't seem to be anything else wrong with the starter, so reassembled and went on a test run. The starter functioned well when hot after the test run. I guess the layer of copper dust was reducing the insulation somewhere.
This is the first time that I have stripped a starter, so was surprised to see copper brushes (expected carbon brushes). Is copper normal for starter motors?
