After being stuck in very slow, heavy traffic for an hour (South Mimms, 30th
July, overturned lorry? Grrrr.) my E34 temp shot up to just under red. Got
it to side of motorway and let it cool down. Seemed ok.
However, temp gauge started dropping to cold then back up again repeatedly.
Got to where I was heading and checked coolant level but no problem there.

Came back to it a few hours later and temp gauge just didnt seem to work at
first then went up to normal (half way) then down again. More importantly,
it wont blow hot air any more through the vents, just under the ashtray?!!?

Thermostat?
Temp sender?
Any ideas?

Cheers all.