Xantia XUD running temp permanently low at 75 not 90

[andmcit]

Newly purchased car with indicated 88k miles!

The car runs well enough but has occasionally stalled and can be a git to hot start but I put this down
to a leaky primer bulb/return pipe circuit which will be relplaced this weekend. The car is showing
symptoms of a leaky heater matrix as it mists slightly and you can smell the unmistakable curry odour
but K-Seal seems to have seen that job off for a while hopefully.

It's the running temperature that is causing some concern. I'm wondering if I need to check that there's
a thermostat fitted in the feed pipe from the head to the rad as without one it will feed any hot water
to cool sooner - probably done by the previous owner to minimise strain on the heater matrix leak.
Would this explain the low reading or am I better suspecting the temp sender or dash instruments?

[Xantidote]

Andrew,

Yes, definitely go for the thermostat check first. Your idea that it might have been removed to ease pressure on matrix holds water (ha )

Could be simply that thermostat has failed. Mine failed, and the temperature the engine ran at was very similar to what you're finding. Easy to replace, most time being spent topping up the coolant and getting rid of the excess air. My only regret was that I didn't get round to doing the job very quickly, and may have encouraged carbon build up on the valves.

What are you doing with TD - thought you were more into V6?

[andmcit]

The car is actually being used by a family friend - v6's are more my thing sure,
although economics dictate that I do run a TD XM 2.5 and Xantia TD too!

Least it seems like the symptoms have been on your car too and it was the
thermostat!

[Old-Guy]

Thermostat was my immediate thought too. Mine failed with opposite problem - the 'Waxstat' had lost most of its wax so 'stat opened little more than a crack - all OK if I drove really gently. Got caught out on M4 in Wales (it goes up and down a lot!) and had to creep back to Gloucestershire where the hills are smaller!

[CitroJim]

Quick test for a thermostat Andrew. Start up from cold and constantly feel the top hose. If it gradually warms then the 'stat is missing or stuck open.

If the 'stat is good the top hose will remain cold right up until the 'stat opens and then the hose will suddenly get hot..

Have you fixed the gear cables on the 2.5 yet?

All TDs in my experience never start as well from hot as they do from cold. Glowplugs are just as important for starting a hot TD as they are for starting from cold..

Do you see any white smoke out of the exhaust whilst hot cranking?

K-Seal is terrible stuff. I have a freeing it helps weld the matrix connector together and makes it jolly tricky to separate when you come to do the matrix

Forte Stop Leak is the best temporary fix...

[Dommo]

My TD only reaches 90 degrees while going up a long and steep hill, it generally sits at 75 even with a new thermostat. I thought it was an overpressurised coolant system not letting the thermostat shut, but it appears to have not gotten any worse in over 2 years so I just accept that coolant temperature. The oil reaches operating temperature still so I don't worry about it.

[cc101]

Hi, I changed my stat the other week as the gauge rarely got above 60, new stat rated 83 degrees and now the gauge stays around 75-80.

Chris.

[lurchy666]

my old 1.9 td always ran at 75 ish only way to gt it any higher was to go up a very steep hill or give it the beans,

my hdi only ever gets to 75 even on them hot days we had a few months back