Water temperature

[Jon S]

Some advice please

My 350 i has recently started to run a bit warmer than usual. Normally the needle settles about half way up the gauge when cruising, but now its between half and 3/4 up the guage when cruising. Also when its warming up the needle goes slowly up the gauge then suddenly goes up to over 3/4 s and comes back down again straight away to its usual position.

I have checked coolant level at swan neck and expansion bottle, checked radiator which looks in good condition and not corroded, checked to see nothing blocking radiator grille, no mayonaise on oil filler cap, no sign of any leaks. Fan works ok

Could it be a thermostat problem ie sticking or not opening fully or something else?

Thanks in advance

JS

[l33]

At a guess, I would try for a duff sensor or an air lock.

But as its a wedge then maybe not ???

[jeff m]

Does sound like a thermostat because it happens at cruising (not just warming up) but I would put new pressure caps on first.
Then consider flushing cooling system. Both non surgical procedures.

[convert]

Had similar problems with my 350. Traced to a leaky swan neck cap.
Replaced this (QH part no FC57 about £2) and bled the system. not happened since.

[grady]

Having fought with this, I'd recommend buying and temporarily swapping your sender for a (relatively) inexpensive digital gauge and matched sensor so you can eliminate 2 major variables and start with an accurate reading.

Make sure you ground the sensor directly to the engine near the sender and not a ground in the cockpit as it can throw the readings off - This may come from prior metal cars but heretofore I thought a ground was a ground but not so in a TVR. Then loop a wire from the engine through the window to the cockpit gauge.

If the reading are normal then hopefully it's old sensor - a cheap fix. If not, you can play with the cooling side until you isolate the problem. Grady

(Who replaced way too many things only to find it was a bum sender that had tested OK in pot of boiling water but was not working properly in situ.)

[Jon S]

Thanks for your replies.

I will try replacing pressure caps (never thought of that!) and sender units first.
Are the sender unit and thermostat standard rover items available over the counter?

[350zwelgje]

I would flush the cooling system (reminded me to do mine as well) and get a new thermostat, especially if this hasn't been done for a long time and for example the thermostat is still the original.... Thermostat is standard Rover and Land Rover, but you need to get the right temperature version. Mine is I think 82 degrees, standard is more (around 90) and I would not recommend that as TVRs run warmer and thus need to start cooling more and earlier.

Rob