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crunchy Off-Road Guru
Joined: 31 Jul 2003 Odometer: 1040 Location: Essex
1986 Land Rover 90nad
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Posted: Thu Mar 16, 2017 4:41 pm Post subject: 1998 300Tdi Disco starting issue
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Hi guys. I've got a brand new battery and that's all fine, charging fine, alternator good, no battery drain, if left for a week battery show 12.6v. Exact same voltage at solenoid so presuming earths all good.
But at cold start it is sluggish to turn over (ie symptoms of a flat battery) and struggles but will start. Testing it after a few minutes running it spins seemingly faster and starts as it should.
I have a cut out switch to the fuel solenoid so can spin it over without it starting and confirm the sluggishness.
Cannot think of anything else but starter motor??
__________________________________ Max. |
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( Gray ) Articulating
Joined: 15 Apr 2012 Odometer: 597
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Posted: Thu Mar 16, 2017 5:23 pm Post subject:
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Check the earth strap from the starter motor. A dodgy earth strap might allow the minimal current from the solenoid but not the large current needed by the starter motor.
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crunchy Off-Road Guru
Joined: 31 Jul 2003 Odometer: 1040 Location: Essex
1986 Land Rover 90nad
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Posted: Thu Mar 16, 2017 6:56 pm Post subject:
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Hi Gray,
Thanks very much for the fast reply. I did check across from the positive (solenoid) to the neg on the solenoid and both ends of the earth braid including the terminal on the starter and all good. This was while engine/ignition off etc not while cranking.
__________________________________ Max. |
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mike328 Articulating
Joined: 10 Dec 2014 Odometer: 793 Location: Suffolk!
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Posted: Thu Mar 16, 2017 8:24 pm Post subject:
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You're measuring voltage, not current (amps), my money is that Grey is right and if you measured the same points when cranking the voltage would drop.
__________________________________ Snap On: Turning drawers into status symbols since 1920. |
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crunchy Off-Road Guru
Joined: 31 Jul 2003 Odometer: 1040 Location: Essex
1986 Land Rover 90nad
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Posted: Fri Mar 17, 2017 9:32 am Post subject:
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OK, this morning (pretty cold) battery showing around 12.45 volts. Across positive of solenoid the same but when cranking (fuel stop solenoid activated) it goes down to 8v or so.
__________________________________ Max. |
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crunchy Off-Road Guru
Joined: 31 Jul 2003 Odometer: 1040 Location: Essex
1986 Land Rover 90nad
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Posted: Fri Mar 17, 2017 2:00 pm Post subject:
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To update - it did start OK - came back after 1/2 hr run and same result with voltage 12.5 down to 8 or so at cranking.
All battery terminals are good - only lead from the negative on this battery is one direct to the chassis.
And then there is the one on the other side from chassis to starter.
I guess next job is to remove both of these and clean the contacts?
And then a new starter?
__________________________________ Max. |
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( Gray ) Articulating
Joined: 15 Apr 2012 Odometer: 597
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Posted: Fri Mar 17, 2017 4:32 pm Post subject:
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After cleaning up the earth points, add an earth strap direct from the starter motor to the battery. Heavy duty welding cables are a popular choice for an extra earth strap.
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crunchy Off-Road Guru
Joined: 31 Jul 2003 Odometer: 1040 Location: Essex
1986 Land Rover 90nad
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( Gray ) Articulating
Joined: 15 Apr 2012 Odometer: 597
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Posted: Sat Mar 18, 2017 8:12 am Post subject:
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I've read that in cold weather a 300tdi starter can draw 600amp current. A good starting point (pardon the pun) would be to look at the size of the current (sorry again) earth strap.
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tilly1 Winch Assistant
Joined: 21 May 2012 Odometer: 86 Location: bolton
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Posted: Sat Mar 18, 2017 11:31 pm Post subject:
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maybe your starter motor is in need of a service is it turning over fast enough
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crunchy Off-Road Guru
Joined: 31 Jul 2003 Odometer: 1040 Location: Essex
1986 Land Rover 90nad
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Posted: Sun Mar 19, 2017 1:12 pm Post subject:
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Another update.
This morning battery was showing 12.95v
When cranking the starter:
Battery dropped to around 9v
Starter voltage dropped to around 7v.
I cleaned all earths through the system and put another charge in the battery.
Subsequently after charge and cleaning:
Battery showed 13.5v
Cranking - battery = 9.8v
Starter = 8.8v
So, the cleaning has helped a little but starter still sluggish.
I could try adding another earth lead but this will need to be around 6ft long to reach.
Or just get a new starter?!
__________________________________ Max. |
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tilly1 Winch Assistant
Joined: 21 May 2012 Odometer: 86 Location: bolton
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Posted: Wed Mar 22, 2017 7:20 pm Post subject:
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just get your starter motor serviced prob dry inside or brushes worn
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