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Intermittent Starting 300tdi


AdeParko

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I seem to have an intermittent starting problem on my 1996 'N' registration 300tdi. Its manual transmission 2.5 tdi.

When going to start the car, it operates as normal. Glow plug light comes on and timers as normal. Then sometimes it starts no problem, but other times there is nothing. No attempt to crank, just a click/clunk. You can usually get it started by repeated attempts at turning the key

The battery is a brand new 019 type with 950cca, and it also has a brand new starter motor and alternator. All of which were fitted last week as part of the cars refurbishment.

The stop solenoid on the back of the injector pump seems to be wired into a 12V cable from the glow plug timer relay on the back of the fuse box. I don't whether this is normal or something that was done by the previous owner as it is just solder into the cable as it enters/leaves the relay

Is there anywhere best where I should start the investigation?

I've been searching on google and a common problem regarding non starting 300tdi's appear to be a "spider" wiring on the alarm?

Also, does anyone know whether the this starting issue would affect an MOT, as its booked in tomorrow

Many thanks

Ade

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By the sound of this it seems you have a power or earth problem. Make sure the terminals on the battery is clean and properly fitted and tightened, then I would make sure the earth cable is making a good contact on the chassis and the one that runs from the chassis to the rear of the transfer box, or it may be from the battery to the rear of the transfer box, either way make sure the earths are really good. Then check the solenoid terminal on the starter is good and fits very firm on the solenoid, also make sure the power cable is making good contact and is tightened properly on the solenoid.

Please be careful when checking the power supply cables, always disconnect the battery when doing these checks.

let us know how it goes.

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If the dash is clicking, then the relay is being triggered, but its contacts could be burnt out, so it's worth trying a new relay. As mentioned above, check the earth strap between the chassis and engine, as they corrode easily and then stop earthing the engine, especially the starter. In that case, what tends to happen is that it tries to earth through the hand brake cable, melting its teflon/PTFE coating and seizing it in its outer sheath. I'd recommend adding a second earth cable from the engine directly to the battery as a precaution.

Failing the above, and assuming the alternator has been charging the new battery correctly, I'd suggest that the new starter's solenoid is not functioning correctly - it's not unheard of for new components to be faulty, and some suppliers have a woeful reputation for it.

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From a recommendation on another forum, I picked one of these up on my way home last night,

AMR4956-IMMOBILISER-CENTRE-CONSOLE-LOOM.

But after pulling the dash apart to fit, starting issue was the same :(

So I then proceeded to remove, brush up and refit all the earth braids. Checked continuity with my tester, and all appears good. But again, no difference to the starting :(

I will look into buying some new earth braids and fitting them, as its not going to hurt anything

I dropped it in for its MOT this morning, so will see how that goes

I will probably look into testing the feed to the starter solenoid to make sure that's OK even when its not starting

If that proves OK, I assume it must be the starter? I which case I'll be getting in touch with Bearmach as its only 5 days old!

Thanks for all the help, keep the suggestions coming if anyone thinks they have an idea as to what it might be

Ade

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Who was the manufacturer of the started motor?

I had a blue box job (Britpart) on my 200tdi and that failed after 12 months in very much the same way, turned out to be the starter solanoid, I would avoid buying an unbranded starter motor full stop, or if you do be prepared for issues. They have to carry so much current the dodgy aftermarket coppies just aren't up to doing it.

Mav

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  • 7 months later...

Sorry to grave dig this thread, but did you ever resolve your issue AdeParko? Trying to fix my parents discovery (P-reg, 300tdi manual) with identical symptoms, happening more and more frequently, but unsure of what exactly is causing it, so any tips may speed up the search!

Thanks

Jake

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Two button, it has a 'spider' that I've heard mentioned under the dash, green alarm box in passenger footwell, and something with 3 wires going onto the injector pump (DDS?), although also has a spade connector on the back of the pump.

Cheers for replying by the way!

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I had the same problem (my model is slightly different to yours - no Spider). My issue was the immobiliser - specifically the starter motor circuit. There is an easy work-around.

Get hold of some scotch-locks...this is reversible is it's doesn't sort your problem out - just remove the earth lead.

See here (hope this ok Mods - feel free to remove link if not!)

Quote

=====

heres a starter relay behinde the drivers front pillar cover, behide there theres a few relays its the one of the yellow relays with the orange wire with a black tracer, i earthed that out and mine starts altho been round the world trying to trace it! it eventually goes back to the green alarm imobiliser/rcl box under the pansenger side kick panel!!

========

End Quote

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This is what was up with mine. After taking the dash to pieces and find SFA, and a few non starts on a tesco car park I was ready to torch the motor! Found the alarm ecu on eBay for the same frequency and replaced it and it's been fine ever since!

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