How hot?

[Condi]

Should a car run? I would have though somewhere around 85-90 degrees, yet my 306 barely gets above 75 even towing a trailer uphill, and I dont think Ive ever seen it above 80. Is the thermostat knackered or is that how hot it should get to?

[Raize]

Cold weather. None of my cars are warming up either.

Oh, and 85-90 degrees is a nice coolant temperature for the fan to come on at.

[rhysenna]

Had this on my car and it was the thermostat that was stuck open. Wasn't letting the engine get past 80. Is your heater on the cold side as well?

[Dave Hedgehog]

my car runs at 105c in londons traffic

[Pig Skill]

Many thermostats tend to open and let the cooled water though at around 82 degrees.

If yours is running <75 then it may well be partially open / not fully closing - this is a common way for a thermostat to fail too.

A car running too cool aint great for efficiency either; might be worth swapping it out for a new one - a full system flush is always good to do just before winter.

[GroundEffect]

Pig Skill said:

Many thermostats tend to open and let the cooled water though at around 82 degrees.

If yours is running <75 then it may well be partially open / not fully closing - this is a common way for a thermostat to fail too.

A car running too cool aint great for efficiency either; might be worth swapping it out for a new one - a full system flush is always good to do just before winter.

You want the car to run as hot as it possibly can - the most efficient.

And 82C is low for a thermostat these days. It's usually over 90C.

It makes no sense for your car to not get hot when towing uphill - if your thermostat was stuck closed it would overheat very quickly and if stuck open, it would function as normal.

[HustleRussell]

I'd say you have a 'stat which isn't closing fully, as someone else said up there ^ this is a common mode of failure.
I'd fix it just for the sake of a more effective heater in this weather!

[Pig Skill]

GroundEffect said:

Pig Skill said:

Many thermostats tend to open and let the cooled water though at around 82 degrees.

If yours is running <75 then it may well be partially open / not fully closing - this is a common way for a thermostat to fail too.

A car running too cool aint great for efficiency either; might be worth swapping it out for a new one - a full system flush is always good to do just before winter.

You want the car to run as hot as it possibly can - the most efficient.

And 82C is low for a thermostat these days. It's usually over 90C.

It makes no sense for your car to not get hot when towing uphill - if your thermostat was stuck closed it would overheat very quickly and if stuck open, it would function as normal.

Yep, but he has a 306

[StoatInACoat]

Which engine is it? All 306 variants run at different temperatures but should warm up more than that in traffic or when flogged. The gauge in them is a bit of a random number generator though which doesn't help.

Do the radiator fans ever kick in?

[Krikkit]

Pig Skill said:

GroundEffect said:

Pig Skill said:

Many thermostats tend to open and let the cooled water though at around 82 degrees.

If yours is running <75 then it may well be partially open / not fully closing - this is a common way for a thermostat to fail too.

A car running too cool aint great for efficiency either; might be worth swapping it out for a new one - a full system flush is always good to do just before winter.

You want the car to run as hot as it possibly can - the most efficient.

And 82C is low for a thermostat these days. It's usually over 90C.

It makes no sense for your car to not get hot when towing uphill - if your thermostat was stuck closed it would overheat very quickly and if stuck open, it would function as normal.

Yep, but he has a 306

The diesel 306's have 83° stats as standard, so you're pretty much there. Petrol ones are hotter at 89/90ish.

[GroundEffect]

HustleRussell said:

I'd say you have a 'stat which isn't closing fully, as someone else said up there ^ this is a common mode of failure.
I'd fix it just for the sake of a more effective heater in this weather!

It can't be that failure mode if the car isn't overheating when towing. If it was partially closing the flow restriction would cause a raise in coolant temp (above nominal) when towing.

[balls-out]

the Mrs's 306 Xsi has run fairly 'cold' since we bought it 10 years ago. I did check when we got it and the main dealer was un concerned.
ISTR issues that if the oil ran too cold it failed to burnoff some contaminant or something - but maybe that from the days of petrol from carbs running down the bores...
Anyway 10 years and 90k miles and it doesn't seem to have done any harm.

[HustleRussell]

GroundEffect said:

HustleRussell said:

I'd say you have a 'stat which isn't closing fully, as someone else said up there ^ this is a common mode of failure.
I'd fix it just for the sake of a more effective heater in this weather!

It can't be that failure mode if the car isn't overheating when towing. If it was partially closing the flow restriction would cause a raise in coolant temp (above nominal) when towing.

of the few failed 'stats I've actually checked, I've had one which opened to it's full extent at the right temperature but the plug didn't seat properly onto the body and the gap caused the engine to overcool.

[Condi]

rhysenna said:

Had this on my car and it was the thermostat that was stuck open. Wasn't letting the engine get past 80. Is your heater on the cold side as well?

Heater is toasty and warm. I've had 'stuck' or broken thermostats before, but this doesnt seem to displaying any obvious signs of a fault other than running a bit cool. Certainly it does open and shut, at least to some extent; that much was obvious when changing the coolant and flushing it through.

Engine is the 2.0Hdi, 90hp. As for the cooling fans, I dont think they do, certainly not very often. Even when it was running stationary for a good while the other day the fans never came on but it seemed to be running quite nice and cool. (IE its normal temp around 75ish.)

From having a quick poke around other forums nobody knows if thats the right temperature or no, its certainly not uncommon for them to be sat at 75, and the general attitude seems to be not to worry about it!

Edited by Condi on Tuesday 6th November 19:25