I could do with some urgent assistance to diagnose the cooling fault which has just developed on my 90 2.5TD, since the 406 is off at the menders again for a week, so the LR is the only transport I have for the moment and it's just let me down.
The vehicle is on its original engine (156000 miles) with, (so far as I can tell since I've only had it about a year) no major services or repairs. It uses almost no oil, which given what I have heard about this engine at this milage I find pretty surprising.
Normally it's used for tootling round the Peak District - rarely more than 15 miles from home - but last weekend (New Year's day) I did a run from near Buxton down to Ross on Wye and back to collect a dumper. It behaved pretty well, but seemed to get quite hot when towing the loaded trailer (upper end of the white section on the dial - never into the red while the engine was running although it would sneak up when the engine was turned off).
Tonight, I have just set out on a short journey and after about three miles, the heater went cold (it's never been very hot, but it actually went from warm to cold this time) and the temperature gauge rushed up to the red region. I stopped and took a look under the bonnet and while the cooling system cap blew steam at me when I (carefully, and with gloves on!) loosened it, the fan drive was loose (ie.e the viscous coupling was not hot) and the engine block was still cold enough to be able to touch with a hand.
I've let the thing cool for twenty minutes (easily long enough - it's well below zero on Tideswell Moor tonight! ) and then driven it home. On the way home, the needle went up to the red, then came down and then went back up again.
My inclination is to think that the thermostat is buggered, and I'll go and take it off in a minute and see what happens without it, but if anyone can confirm this, or give me any other ideas (or, more significantly, tell me if they think this is a pre-cursor to something more serious, such as water pump failure), I'd be grateful.
TIA
Nick.