Occassional starting issue.

[RF LR D1]

Hello, 

I've only joined the forum tonight but I've used the technical archives for a number of years now and found them very helpful. So first of all Hello, and thank you all for your previous inputs to the forums. 

I've joined tonight because I need help (again) and I cannot find anything in the archives. I have a 3 door Discovery 300tdi 1994 (no spider) with 230k on the clock that I use for travelling around the UK and that has, in general, been a very reliable example. Until recently...

  I have a starting issue in that sometimes it just wont.    I put the key in the ignition, turn the key and leave it until the glowplug light on the dash clears and then go that last click to crank it and sometimes it wont even try to crank.  Everything else works as it should i.e. radio, lights, windows etc.There doesnt seem to be any particular reason or event that cause this and it's not very often - although it has a habit of doing it when you need to be somewhere.

I have found that if I put a jump lead from the block to the battery negative it will crank fine. I know this would point to bad earths so I've had them all off, cleaned them up and put them back again with a smear of vaseline. I've also tested the joints with a ductor borrowed from work. The thing is I can start it in this manner, take the jump lead off, stop the engine and then it will crank over and start again straight away without any issues and it'll be fine for, usually, weeks afterwards. 

I know I could just put a large cable from the negative to the block - and save myself having to "jump" it - but I feel this is masking the issue instead of resolving it. 

If anyone has any suggestions on why my Disco sometimes throws a tantrum I would appreciate hearing them.

Thanks in advance. 

P.s. I'm not a total novice with mechanics, I've had this Disco for 3 years - 6 months of which was replacing rotten steel and getting it back up to a mechanically sound condition and had a 200tdi Defender (same story) for 3 years prior -but I'm scratching my head with this problem. 

 

[Alsace_rangie]

I had a similar problem.  Sometimes just rolling the car a meter or so would make it turn over.

I did have an issue with the starter solenoid (tap with a hammer to get it going), but even after replacing that it would sometimes just act dead.  Earth (braided cable) had been off, contact points on the chassis filed etc.

However, one day it wouldn't start and all I did was wiggle the earth strap (starter to chassis) and it turned.  So I fitted another strap (nice braided copper one) as well.  Worked ever since.  The original strap looked fine, so only logic I can think of is that enough of the wires forming the braid were broken and  just touching to cause the intermittent break in the earth..

[elbekko]

Yeah, the cables can break internally. Sometimes you don't even notice with a multimeter because the current is so low.