Question about T27 Avensis 1.8i thermostat/engine heat issue

[JiiN]

Here in Finland we have winter now, so cold weathers became. I drove with my T27 1.8i Avensis couple days ago when air temperature dropped to -20 Celsius (-4 Fahrenheit).

I noticed engine heat cauge didnt rise to normal in 20 kilometeres (12,5 miles) trip with 80km/h (50mph) speed with proper pre-heat before driving. I used bluetooth OBD plug to check temperature with Torque app, and it told the coolant temperature was only about 66 Celsius (150 Fahrenheit). My previous car was E12 1.6i Corolla and it made normal temperature in same trip, no matter how cold it was outside.

Does these cars have issues with engine thermostat? Or is these cars just made to drive only in summer-time?

[TonyHSD]

This maybe a normal to happen when it’s so cold outside and you are driving at speeds over 20mph the wind is cooling down the engine block. To test weather the thermostat is faulty you can rise the rpm while standing and let the car reach normal operating temperature, then start driving and drive outside town at higher speeds and if temperature gauge drops dramatically then thermostat been stuck open and let engine coolant circulate through radiator and gets blown by freezing air. Also you can touch cooling system hoses to check which ones are hot and cold👍 

[Konrad C]

Here in the UK, especially where I live in Greater London, it rare for the temperature to go low as -5°c or -10°c, let alone -20°c. Adding to Tony's reply, what about covering the grill, so less cold air is hitting the radiator. I have yet to drive my car is extreme cold conditions. Only last summer, I replaced my water pump and mixed Toyota concentrated  red coolant with de-ionised water at 50% ratio. Today the temperature was 2°C and the car took a little longer to warm up, but the cabin got comfortable quickly. Overall the valvematic engine has not had any issues with the thermostat.

[JiiN]

I'll test probably tomorrow Tony's advice. It was few days little warmer weather and now it looks like it is getting colder again (-20c right now).

I havent need cover the grill in any my previous petrol cars if the thermostat is working properly (last one was E12 1.6i Corolla). I thought it is only diesel cars problem 😄

[TonyHSD]

When cold outside the air stream hits not only the radiators but goes through them and air cooling the engine block, another reason why engines get warmer slower, however if thermostat works as normal will stay closed and the coolant will only circulate via the car heater’s core to heat up the cabin. If the thermostat stays open in cold weather (faulty) the coolant will circulate through the radiator and will be cooled down by this ice cold air, if you drive at higher speeds and engine is under constant load with faulty thermostat the coolant temperature will drop and you will see the change on the dashboard, if you are driving downhill engine it’s not loaded, then it’s normal temperature to drop because of the cold stream that hits the engine block. Here is the reason why Toyota has introduced active grill with 2016 onwards Prius and other hybrids, grill closes automatically to keep engine  warm when needed. 👍My Auris hybrid very often in the cold weather when driving in town on ev mode cools down and temperature drops (old model no active grill) then when back on the motorway and load the car thermostat seems to work fine as the engine gets warm back again. 👍

[JiiN]

So i did those methods to test thermostat. It looks like the thermostat is OK. Temperature rises up (normal) and stays there if speed goes little higher and engine gets more load. Maybe these "newer" cars are made so economical (low fuel consumption, low emission, etc), so these doesn't just warm so easily like those older cars.

[JiiN]

This problem didn't stop bothering me, so i chanced thermostat (only 25€/22£ try) and it looks like my Avensis gets warmer faster than with old thermostat.

Original (114000km/70800miles) thermostat got little rusty already so i think chancing it was right thing. I tried upload some pics about old thermostat, but forum gives me error everytime.

[Konrad C]

Glad you have found the possible cause. Since your post, we had some temperatures of just under 0°C in London and the south east. I can tell you, when I set the temperature to say 23°C, the car was warm and comfortable. I increased the temperature to 26°C and it was hot. As I said in my previous post, I changed the water pump and used 50% mix of long life Toyota coolant and de-ionised water. Everything looked clean. Here is my post on that - 

I have noticed other posters having issues posting photos, but I have not had any issues. May be there is a setting out! 

[JiiN]

I noticed with old thermostat that coolant temperature didn't rise to normal temperature. And Torque phone app also said it was about 66-70°C. Still car was warm inside, but i noticed that heater fan speed was about 75% almost all the time at Auto-mode and temperature set at 20°C. My car had Toyota Long Life Pink coolant and that was also what i used. Everything else was nice and clean except the termostat was rusty.

[Konrad C]

I looked at the following video and it is easy access to the thermostat. This engine has a good layout for most tasks.

I don't think you need to remove the hose, but then I have the hose clip plier tool. Hopefully I won't need to do that job.

 

[JiiN]

It is pretty easy task to do. I didn't drain all coolant away, previous owner had changed it little while ago. Just opened those two 10mm nut from a thermostat case (don't know actual name to it) and let the coolant drain. First i took expansion tank hose off from a radiator end with normal pliers and taped hose end upper than coolant was at tank (so i saved coolant in tank). When thermostat was replaced i started car and poured new coolant slowly to expansion tank. About 3 litres coolant came out/went in. If You replace thermostat, it is important remember to get new seal around the new thermostat.