Groaning Starter Motors

[helicopterdcr]

I'm sure this is a basic fault, but it's years since I took a starter motor off a car...On turning the key, the only result was what I can best describe as a 'groaning' noise, and the engine didn't turn over. Fortunately I was on a hill and just bump started the car to get home.
I checked all the earths, battery/chassis etc and connections to the motor. I checked the leads for continuity and turned the squared end of the motor. Finally, having removed the motor, I found that it motored beautifully on a battery. The bendix wasn't all that dirty, but everything was all cleaned up with paraffin, and motor re-installed. Hey presto and it all works again.
Can anyone tell mw what the problem is/was likely to be?
Thanks, Dave

[Dicky Blighter]

Could have been bad connection but more obvious is a flat battery? could be on it's way out.

[helicopterdcr]

DB, Battery seems fine and doesn't fade when cranking the engine - I think the battery is fairly new. It was my first thought too; I assumed at the time that it was the bendix groaning but under load and not engaging - is this likely?...Dave

[Steve Cureton]

Either a poor connection which the work you've done has rectified or it could be worn brushes, by spinning it without load the brush connection could have been re-established - but beware as if this is the cause then it's likely to happen again.

[herald948]

It is rather common for major connections to get "dirty"; probably the R&R of the starter temporarily "cured" the dirty terminal problem. To be safe and sure, I would go back and clean up all those major battery and starter/ solenoid connections again.

Oh, and it also never hurts to clean off the starter "Bendix" as you did, as they do sometimes get grimy. (Just don't oil the Bendix again, but maybe use a tiny amount of a dry lubricant such as graphite, which won't attract future grime!)

I'd say there's about a 98% chance your starter is fine and will be for years to come.

[helicopterdcr]

Thanks for those ideas. I'll go back and clean the connections and check the brushes as suggested, as it's probably better for my sanity than getting a help-come-and-rescue-me call from a stranded Mrs Helicopter. Cheers, Dave

[Pete Lewis]

A duff field winding can give a dramatic power loss symptoms of flat battery, motor
increases with speed the longer you crank,  was the light sring on the bendix ok as pinion might have just engaged and on compression lacked the torque to turn over,,
I fitted a high torque geared starter which flings the 1600 over at a furious rate
whatever the battery state  and consumes no amps at all..  peter

[helicopterdcr]

Well, I finally had to go round and clean it all up again as the starter is up to its groaning trick again, just after I'd had a pint (sshh) at lunchtime and had to drag some puzzled customers out of the pub to bump start me. I think they were amazed that she fired up at a gentle walking pace and within 5 yards...

I cleaned up all the major connections (more thoroughly this time), removed and dressed the brushes up a bit (they must be pretty ancient, as they face onto the end of the commutator - I thought they usually bore onto the 'sides' of a commutator). All looked good, and when bolted back into position the starter wouldn't turn. Taking it off again, I cleaned up the bendix - which I hadn't touched this time - and hey presto. I think the bendix is at fault. Is it possible to buy a new one? The brushes moved freely and looked to have enough meat on them...the bendix spring seemed OK to me, although the teeth are showing significant signs of wear. Perhaps I should consider  a hight torque geared starter (where do I find one of those?).

Cheers, Dave