Overcooling? Where does your temp gauge sit?

[capt jack]

For what it'll cost definitely change the thermostat. And from recent experience with our S70 if you can get a genuine Volvo one you'll be surprised at how little it'll cost - and it will of course fit and work perfectly.

But do go carefully if the stat housing is the same soft alloy as on the x70 five pot engines. It's easy to crack them with over-enthusiastic loosening of the Torx bolts - which themselves are made of soft chocolate.

As well as the thermostat I'd suggest getting a couple of spare bolts too, and then soaking the old in WD40 before attempting removal.

Jack

[TonyS9]

There are 2 thermostats (87+92C), and I have never been able to allocate them to a specific year or model. It might be more country related. Anyway I usually find 92C is the right one for the UK, warmer for this colder climate. The 88C ones seem to sit a bit low on the gauge.

As other have said you should not have an over cooling problem, either the gauage is wrong or your thermostat is sticky.

[Forrest]

I think the perceived wisdom is that 87°C/189°F is for Turbo engines and the 92°C/198°F is for normally aspirated but in practice with normal road driving there is unlikely to be any noticeable difference.

[dan 244]

Both my turbos have the 92 deg one, supplied and listed as correct by Volvo about £15 if I remember correctly. But I had seen the 87 for turbo posted somewhere else. But both mine sit with the needle straight up all the time.

[Laird Scooby]

Originally Posted by Forrest

I think the perceived wisdom is that 87°C/189°F is for Turbo engines and the 92°C/198°F is for normally aspirated but in practice with normal road driving there is unlikely to be any noticeable difference.

I think Tony is probably right, it's a territorial thing. On my Rover, the "standard UK 'stat" on the 827 is 78C, the "dealer fit option" is 82C (for cars that are slow to warm up allegedly) but the 216/416 from 89-96 which uses the same 'stat has the 88C 'stat as standard for the UK which is sold as the "Nordic" 'stat elsewhere for the 827 - i suspect Volvo have done similar!

With that in mind, i run an 88C 'stat in my Rover and enjoy faster warm up, better heater and improved power and economy.

Also when i renewed the 'stat in my 760, i went for the hottest i could find which at the time i think was 88C, might have been 92C but when i replace it then i'll hunt down a 92C if i can find one.

[kelvinp]

Originally Posted by lnparry

Thanks everyone - looks like I need to add a thermostat to my to-do list. I'm just surprised it didn't show up as a problem in the summer as I presumed a dodgy 'stat would have lead to overheating rather than over-cooling?

Agree with OMC 47's point as have had problems with other cars in this area previously.

To answer Dave's points; I had a leak from either the rear gasket or gland on the old (original) pump. No overheating but as the timing belt was way past its sell buy date and I had a leak from the front camshaft seal, decided to have the front end of the motor all sorted. Plain "blue-green" antifreeze not OAT.

Cheers,
LeeP

It depends on how the thermostat fails. If it sticks closed then the engine would overheat in no time, but if it's stuck open or opens too early then the car will probably run quite happily - sure years ago people would remove the thermostats in summer.

My suspicion would be that the thermostat is not fully closing, if it was stuck fully open I suspect the engine would struggle to warm up at all. I took my suspect one out an suspended it in a saucepan of water and warmed it up - it still fully opened at 92C but wouldn't fully close when cooled down.

when I took it out, it was a Volvo branded one dated 12 03 and I have to say it's the only other time I've ever had to change a defective thermostat, the other being years ago in a P4 Rover which wouldn't warm up and that was an old bellows thermostat which was weak and opening far too early.

[Laird Scooby]

Originally Posted by kelvinp

It depends on how the thermostat fails. If it sticks closed then the engine would overheat in no time, but if it's stuck open or opens too early then the car will probably run quite happily -

................... until it blows the head gasket because the head has turned into a banana!

[baggy798]

Mine sits at 190F (~88C) and the heater seems ok on full blast. In order for the fan to kick in the temp has to reach 230F (~110C).

https://i.postimg.cc/bvt0N9LQ/940volt7.jpg

I had a lazy stat once and it struggled to get up to temp, usually hovering around 170F (~77C) for an age. Not sure with the stock compensated gauge if you would even notice that.

[AllHailKingVolvo]

My first 945 had a sticky stat and would run around town nicely at the midway point of the dial, but on a run would gradually go almost entirely back down to C. I put a new stat in it (a good point made earlier in this thread re electrolysis, I broke a stud when changing mine and had to replace it!) and all was well.

In all three of my 740s the needle has stayed bolt upright. My 240 usually sits in the middle of the dial with an occasional 5% drift north until the fan cools it back down again in summer traffic. My current 940 sits at just a hair past the midway point...maybe 53%. Never moves once warmed up, though. It could be that it has the 92deg stat in for NA cars and should have the 87. I'm not in a huge rush to check and change it as five degrees won't cause any loss of sleep, but will sort it soon enough.

[martin calva]

I agree with others - most likely thermostat. When I first had my V90, the temperature gauge never got up to normal. When I drove fast on the autoroute, the temperature actually fell (presumably more wind through the radiator increasing the cooling).

To my amazement, the car had no thermostat. And, in view of the difficulty of undoing the bolts on the thermostat, housing it had been like that for a long time.

Years back, I had a 260 which never got up to the correct indicated temperature. As soon as I changed the thermostat (which was stuck open) the temperature got up to the normal level. And the fuel consumption fell from 14 mpg to 22 mpg.