Apologies for long post but I want to try and include everything.
I have a 99 S reg Mk4 Diesel Astra with the GM engine.
It was left unused for a couple of days in very cold temperatures and when I went to start it I just got a loud clicking noise from the starter solenoid. I attached jump leads from another car but it still just clicked and wouldnt turn over. After about 20 mins however it started turning over and the clicking stopped. Fully charged the battery but now have the problem that it is turning over but not starting. It doesnt sound right when turning over. Changed the starter motor. Same problem. Checked glow plugs with voltmeter, all are ok and glowplug light on dash lights up and goes out as normal.
I then noticed coolant was frozen, previous owner (not me really) obviously put plain water and no antifreeze in. I put the car in the garage with a heater on it and left for 24 hours. Fully defrosted, drained radiator and refilled with antifreeze and water. No sign of any leaks. Checked cam belt, aligned correctly, all marks line up and no damage to the belt. (think I got away with it). But car still wont start.
Engine management light doesn't flash which would indicate immobilisor is armed.
I'm out of ideas. Only other thing that may be relevant but I cant think how is that a couple of weeks ago I put 5 litres of petrol in it when it was almost empty and ran it for 1/2 mile until engine cut out when I realised what I'd done. Got it recovered to home where I drained the tank, changed the fuel filter and filled it up with diesel. Started and ran fine with no problems. Have done about 300 miles over about 10 different journeys since then with no problems.
Can anyone think what the problem may be ? Eliminated the battery, starter motor, frozen water pump and glow plugs and now I'm stuck.
Oh and no the immobiliser chip hasn't fallen out of the key.