Hi All So, getting ready for the summer I noticed the engine was cranking very slowly. After checking all the obvious things it became clear that the starter motor wasn't pulling much current. I took the motor to a Bosch dealer and he told me the poles had demagnetized. Everything else inside it was ok. This is a new one on me. Anyone else had this issue?
I've never personally seen this. But too much current or overloading a DC motor can cause demagnetization.
Is it a modern PMGR starter? I thought the originals were not permanent magnet starters but field coils?
Morning Richard, Why don't you go back to the original Bosch starter, They are damn good starters and all the parts are available, at least here in Spain. Just an idea I'm tacking mine apart right now, just to check brushes and inside condition. John.
The PMGR (permanent magnet gear reduction) starters are nice and light but like the old ignition magnetos, they eventually lose their magnetism. The hot headers don't help so put a heat shield around it if you don't have the shielded headers. If you have the big, old Bosch starter you should find a new auto electrical shop as there are no magnets to demagnitise in the old starters.
It had a non standard starter motor. I think the Bosch guy was referring to the magnets fixed onto the outer shell. they were very weak. Bought a new Bosch original part and now everything's ok.
