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Intermittent starter motor problem - help please!
adrianreeve - 27/4/12 at 03:12 PM

Hi guys, car is now finished at Atspeed, all good, very happy. One small issue that came up was a duff starter motor. Atspeed replaced it with a recon one, but have said that sometimes the starter is still a little reluctant to turn over. They and I both suspect an earthing issue, but there is a brand new earth strap going directly from the starter to the chassis, so don't know what else to do really!

Answers on a postcard please...!!!!

Cheers

Adrian

big-vee-twin - 27/4/12 at 03:19 PM

Main Earth straight from the battery -ve to the engine block, with a smaller earth from engine to chassis to serve the electics.

daviep - 27/4/12 at 03:20 PM

Is there also a good strap from the battery -VE to the chassis and are all the connections nice and clean and tight and not on top of paint or rust?

If they are then it's not an earth fault.

Cheers
Davie

[Edited on 27/4/12 by daviep]

adrianreeve - 27/4/12 at 03:43 PM

I have an earth from the battery to the chassis, and one from the chassis to the engine block. Would it make much difference then having the earth to the engine block direct from the battery? I assumed the chassis would be a good enough conductor. Easy to check with another longer earth lead i guess!

Cheers

Adrian

Agriv8 - 27/4/12 at 03:51 PM

quote:
Originally posted by adrianreeve
I have an earth from the battery to the chassis, and one from the chassis to the engine block. Would it make much difference then having the earth to the engine block direct from the battery? I assumed the chassis would be a good enough conductor. Easy to check with another longer earth lead i guess!

Cheers

Adrian


a jump lead could be your freind here to assis fault finding

regtds agriv8

daviep - 27/4/12 at 04:04 PM

Quick and dirty method if you think you have a bad connection, pull the ignition wire off the coil to stop the engine starting and then turn the engine over on the the starter for a few seconds, have a feel at all the cables and connections +ve and earth, if you have a bad connection it will be nice and warm.

A more scientific method would be to do a voltage drop check. Set your meter to volts, put one probe on the +ve battery terminal and the other on the terminal on the starter solenoid which has the very short cable to the starter motor. Crank the engine (still with coil disonnected) and watch the volt meter, you shoudn't read more than about 0.5v, that's the amount of voltage being lost in the cables and connections.

Do the same with the earth side, one probe on battery -ve nd the other on the starter motor casing.

If you get any high readings indicating a lot of voltage is being dropped somewhere just start moving the probe back towards the battery one connection at a time until the drop disappears.

Cheers
Davie

big-vee-twin - 27/4/12 at 04:07 PM

Leads to the starter in theory should be as short as possible with minimum joints.

On a 12v system, small amounts of resistance can make a difference especially at heavy currents.

ashg - 27/4/12 at 09:39 PM

are you sure its not binding? a couple of the skcc lot had similar troubles and after fitting a different model starter it was worted. think it may have been a burton high torque one but am only 60% sure on that.

adrianreeve - 27/4/12 at 09:55 PM

Did have similar concerns Ash. Any idea what model they replaced it with?

Cheers

Adrian