I have a 2004 Mk4 Astra 1.7 CDTi Sport that I bought a month or two ago, and I've got a strange problem.
On Monday the engine cut out on the M3. The engine management light came on with the ignition, flickered once and then stayed on. It would turn over, but wouldn't start until an hour later when the recovery man turned up (typical!) He said there weren't any fault codes showing, but I had disconnected the battery for 5 mins to see if that reset it. It was then OK for 30 miles home at 70mph.
On Tuesday it got me to work (55 miles) in the morning with no problem, but on the way home (ambient temp 20 C) it cut out again after about 8 miles. The water and engine management lights now stayed on. I waited for half an hour, and it started again and got me about another few miles before cutting out again just the same. When it starts again, the water light goes out as normal, but the EM light stays on until it's revved to about 2000rpm.
The engine is hot, and the heater works. I tried driving with the heater on to take heat out of the system but it didn't help. Although the engine and expansion tank are hot, the temp gauge doesn't go above 85 and I think the radiator was cold (though today I've noticed that there appears to be another radiator of some sort in front of part of the main one and I may have been touching that.) The top pipe into the radiator is hot though.
Today I've tried replacing the thermostat, but before the engine warmed enough to register on the temp gauge the thermostat gasket sprung a leak anyway so I've had to stop. I tried that 2-pedal error code trick, but nothing happened.
There doesn't appear to be any water in the oil, the oil is full, the water was a bit low on Monday but it doesn't seem to be losing any more. I suspect that the engine is getting hot enough to cut out (though I don't know whether there's a mechanism for that) so as the temp wasn't going high that made me think the thermostat might not be opening. It does open in boiling water though.
Tomorrow I'll try it again and maybe take out the gasket (there wasn't one there originally) or try some Hematite, but until then:
Does anyone have any idea what the problem might be please?
Thanks in advance!