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blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17367

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

Unusual starter motor fault

An unusual fault for the forums technical panel to consider:

Ever since I bought it about 13 years ago, my TDCi has every once in a while behaved as though the battery is flat, i.e., when you turn the key to crank the engine you hear the start engage, the engine doesn't turn, the panel lights go out as with is a very heavy drain on the battery, and nothing else happens. Usually if you release the key and try again at about the third or fourth attempt it will crank with enthusiasm and start normally. If you measure the battery voltage it is always good (even if you do so immediately after it has done this and before starting the engine) so the battery is not, in fact, flat.

My assumption is that it is a starter or solenoid fault of some kind, but it has happened so infrequently that I have never got round to changing the starter (although I carry a spare just in case).

My battery is also the original fitted in 2007 by the factory, so it is 15 years old and has done 260k miles. It owes me nothing, and I am frankly amazed that it still performs as well as it does.

Earlier this week the failure-to-crank effect happened again, however on this occasion repeated attempts to crank didn't work. My immediate conclusion was that this time the battery had failed and I genuinely had a flat battery. Out with the jump leads, hook them up to another vehicle, and the Defender cranked and started immediately. More out of interest than anything else, I then disconnected the jump leads, shut down the engine, and measure the battery voltage - full charge. I tried starting the engine, and it cranked perfectly and at full speed and started. Five times in a row. My conclusion - not a flat battery but the same infrequent problem but this time more persistent.

So my puzzle now is what could be wrong with a starter motor that means that perhaps on 1 in 100 starts it fails to crank (with flat-battery-like symptoms) but cranks normally with a second battery in parallel (i.e., jump start configuration). I can think of faults which would cause the failure to crank, I can even think of some which would be negated by having two batteries in series (i.e., 24 Volts), but I can't think of any which would then be negated by having two batteries in parallel, the only difference being that twice the is current available, since this would seem to rule out impedance faults such as faulty solenoid contacts, or even stator or commutator windings.

It's a bit of a puzzle, and if anyone has either experience of anything similar or any ideas I would be fascinated to hear.

(The other possibility of course is that it is purely coincidental that connecting the second battery apparently made a difference and it was going to work on that attempt anyway. Until it does it again and I can again connect a second battery I won't know for sure, but I do now have a second battery in the back just in case).

15th Nov 2022 4:42pm

MK

Member Since: 28 Aug 2008
Location: Santiago
Posts: 2414

2007 Defender 110 Puma 2.4 SW Chawton White

In all those years have you changed the starter relay? Puma 110" SW

.............................................................
Earth first. Other planets later

15th Nov 2022 6:16pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17367

No, and it wouldn't be my first suspect but no harm in trying next it happens.

15th Nov 2022 6:48pm

Birdy

Member Since: 07 Oct 2011
Location: Côte d'Azur
Posts: 865

2011 Defender 110 Puma 2.4 XS CSW Santorini Black

Similar(?) problem in that my daughter recently flew over to France to drive a vehicle back to the UK for sale. You’ve guessed it, on the morning she was to leave, the click click click of a flat battery or a loose connection. The battery ISN’T easily got to on this model, it’s underneath the rear seats in front of the rear axle and only accessible from underneath. Push started easily, voltmeter showed charging at 14 odd volts, lights etc. working perfectly. Switch off, try the starter, click, click, click….

To cut a long story short, she drove to Calais, DFDS to Dover, it’s amazing how many guys volunteered to push-start a young girl driving a Morgan whenever she had to stop for petrol or drive off the ship.

She stopped off at the Morgan dealer in Kent, a faulty starter motor was diagnosed. They didn’t have one in stock, took one off a show-room vehicle on the understanding that when another one was sourced she’d return so they could swap them back.

New starter motor, switch on, click, click click. Starter motors exchanged, new battery fitted. Perfect! They’d checked the battery on the car with a Drop Tester, but somehow it was only failing when the full load of the starter motor was required.

Why not try running with another battery before changing relays, starter motor etc?

Peter

15th Nov 2022 7:06pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17367

It's certainly easier to change to battery than then starter (especially since I have underchassis protection). Odd though that it's happened for 13 years.

15th Nov 2022 7:20pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20339

If you do change battery I highly recommend Yuasa Silver. Very pleased with mine. $W33T $0U7H3RN $UG4R
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15th Nov 2022 7:21pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17367

I have a Varta LED95 EFB standing by if needed.

On reflection I don't think it can possibly be a relay fault because the starter is engaging and attempting to crank. Not only can your hear it doing this but the voltage drop caused by the stalled motor (no back emf) browns out the other electrical systems. The relay must therefore be energising correctly.

15th Nov 2022 8:05pm

LandRoverAnorak

Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

High resistance in the ignition switch, perhaps? It sounds very similar to when my switch failed and there was evidence of excessive heat on one of the contacts:

Click image to enlarge Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia

15th Nov 2022 9:05pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17367

Again I could understand a fault with the switch leading to a failure of the starter to engage, but not to a fully-engaged but non-cranking starter.

15th Nov 2022 9:12pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2641

I had this on a Tdi years ago. I never solved it despite changing the starter and the battery, it was always sporadic. I can only surmise it was a poor connection on the solenoid or something.

15th Nov 2022 9:26pm

LandRoverAnorak

Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

Honestly, what you're describing sounds exactly like what I experienced. Turn the key and there's a brief lurch as it tries to start and then nothing - all lights out as if a dead short. It got progressively worse over several months until it failed completely.

It seems to me that connecting a second battery might give enough oomph (technical term) to overcome any high resistance and, of course, once it's started the problem goes away. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia

15th Nov 2022 9:29pm

MR_JAMES

Member Since: 10 Oct 2013
Location: ESSEX
Posts: 248

2011 Defender 90 Puma 2.4 XS CSW Stornoway Grey

I've got a lucas m79 from a metro that sounds like its doing the same thing. (The engine is on the floor on a pallet) Jumping the start terminal it is spinning up but the solenoid isn't pushing the drive out far enough to mesh with the flywheel - in my case the lever connecting the two is partly seized. Maybe yours is too. 1953 80"
1987 mini city e
2011 90"

15th Nov 2022 9:31pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17367

^ Presumably in this case you hear the starter spinning, which I don't.

LRA, did a new starter fix your problem?

15th Nov 2022 10:51pm

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3414

2012 Defender 90 Puma 2.2 CSW Santorini Black

Do the lights on the dash go completely out, or they dim?
If there is such a voltage drop (as you say due to no back emf from the starter not spinning), would that not draw enough power from the solenoid, triggering the click click click sound as the power to the solenoid is restored when the solenoid itself remove the power to the starter?

So if the dash lights are going off, perhaps there is a voltage threshold that the lights can operate at (I do not know if the lights in dash are leds or old incandescents. Unless it is designed to cut off power from everything else except the ecu and the starter itself during cranking. Though that I do not know either. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

15th Nov 2022 11:56pm

LandRoverAnorak

Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

blackwolf wrote:
^ Presumably in this case you hear the starter spinning, which I don't.

LRA, did a new starter fix your problem?

No, it was a new ignition switch. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia

16th Nov 2022 6:54am

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