razzle308
however what i have narrowed down is when it get warm it won't always start.
The solenoid clicks and if the starter engages it makes a nasty grrrrr noise.

Sounds similar to a problem a friend once had.  He used to carry a bottle of water around to pour on his starter when it was hot.  Cooling it down got it to work every time.  

you can prob count out the ignition switch.
If it operates the starter that is all it has to do - after that it is the soenoid switching.
its a doozy thats for sure.
 
I'm not solving it with a water bottle Sorry - but thats just not me.

razzle308


I'm not solving it with a water bottle Sorry - but thats just not me.

Yeah, it was pretty amusing watching him do that.

Maybe that's why the load test at the auto electrician doesn't pick it up.
I had the same problem with a starter from an old XT falcon. When the motor warms up, the worn out parts inside the starter expand causing it to seize up. It sounds like the starter motor is the problem.
Have a look at this
 
http://www.wgcarbs.com/forum/index.php?topic=1194.0;wap2

You should also note that running undersized cables to a starter motor will cause it damage.  Standard size when the battery is in the engine bay is about 16mm square.

thanks ratta.
The s/motor has been rebuilt. (guess that doesn't mean foolproof)
 
so the main v+ cable to the front wich has served well for years is 12mm(inc insul) so lets say 10mm.
The earth from batt to bod is 9mm
bod to engine is 7mm wich is wy bigger than stock and is only 15cm long
 
I think i just have to wait till it happens at home again so i can run some tests.
 

Why don't you just replace the s/motor with one you know works?  Must be someone around you can borrow one from.
 
Or even jury rig the battery up so it's in the engine bay to see if it is your cables?
 
Sounds like it's the s/motor to me.
 
Matt 

With what you saying in previous posts it is a fu**ed starter. I have seen this issue a lot.
 The 'rebuilt' starter possibly only got a new solenoid, cleanout and a paintjob, making it test bench ok (no load) and look pretty. The problem is a lot of the places now dont do in depth rebuilds any more which makes a lot of the younger ones just not competent/experienced enough. Other times they arent honest enough to say sorry I cant get all the parts to recon this starter properly or they are just a bunch of sharks ripping you off. In any case if it has been done recently aproach the place and politely demand they sort it out. 
 
Cheers

Small battery cables can cause an intermitant fault as well. Even though they have worked fine for years, the heating and cooling of the cable can cause damage inside, which will at times, with the right conditions met, cause a very high resistance, thus giving you a low cranking voltage.
I would agree with either changing the cables for bigger ones or remounting the battery in the engine bay for a while and see if the fault persist.
Intermitant electrical faults are a pain and are generally a trial and error fix

The solenoid on the starter could be faulty, susceptible to heat lock, or bad supply voltage. I would first put a relay on the start circuit to make sure the solenoid is engaging with at least 12v. Next step would be to heat wrap it.