overheating?

back again guys...

my 1.8 kseries is at it again, driving through germany last week all seemed good, just replaced the inlet manifold gasket, prt been good since winter....
drove for about 45 mins on the autobahn ( sensibly i might add it was 35 degrees outside) no faster than 70 mainly around 60mph then the car just switched off... no oil in the coolant or vice versa, got picked up and garage pressure tested it..all goood except flat battery from the blinkers

starts up fine 40 mins down the road dead again, 2 hours later it started again, 20 mins driving stopped again, flat battery again
obviously a goosed alternator and over heating

the confusing bit is that the temp guage never shifted above the middle!!!!
it's on a truck coming home in the next few days since stopping dead on the autobahn gets a bit scary.

any ideas other than petrol and matches?

If you are finishing up with a flat battery, the most common cause is a bad earth!

Check them all and make sure that they are clean and tight!

that would make sense as to why the stereo turns itself off then on again when driving too actually, nice one i'll check that today!

it was the feckin PRT ! stripped the whole cooling system and checked it all, the PRT even opened when i poured boiling water through it in the kitchen.......

i was literally about to go back to no thermostat and i decided while its hot i'll just smack the stat housing with a spanner... hey presto, hot bottom rad pipe! the thing was brand new straight from land rover and it was stuck shut!

and the battery was goosed