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Discussion Starter · #1 ·
Hi could some subie expert please explain and maybe clarify common misunderstanding :)

True or false
1. Car is cold Coolant Reservoir level should be on Min Level
2. When car is warm coolant reservoir level will go to max level and that is a normal behaviour

Question
What is the correct way to fill up coolant, is it Top up the radiator then top up the reservoir to Min level?
Does driving fast / high revving will cause the coolant reservoir level goes higher?
what happen to me is some times at the end of a 1 hour drive on the highway, I check the reservoir level , some times it is under max, and sometimes it is over max level. only one observation I can make is that when I drive fast, and some time revving to around 4000 - 4500 RPM on 4th gear, at the end of the drive the coolant reservoir level is higher. but when I drive at cruising speed / speed limit, the collant reservoir level is below MAX / Lower.

another time I top up the radiator and reservoir to the max level. then after a 30 min drive, the reservoir is overflowing. is that normal? is there a chance that the car might also overheating? .

Some background info. I purchase this car november 2008, and the temperature gauge does not work. the car been driven for 30,000 kms and it's been fine so far. and I top up about 3 liters of coolant during the 1 year period

Sorry if the sentence are run-on and hard to understand

thank you
 

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2007 Forester Sports XT 4EAT
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Lots of opinions on this subject! :icon_eek: This thread is a pretty good one to read. :wink:

As for me, I want the coolant on the "full" line, when checked cold. Cold means the vehicle has set overnight & hasn't been run. Low means low, add coolant to the full line when it's cold. During normal engine operations, the coolant level will rise above the full line, about half ways from the full line to the top of the coolant reservoir. I've never had any of my vehicles coolant level to go above that level & none have ever overflowed. :smile:

The coolant, 50/50 mix, is always added to the coolant reservoir, unless it's bone dry & you may have to check the level at the radiator. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2000 2 Outbacks 1Man , 1 Auto
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Hi ndondo, 3 litres seems to be a fair bit to be topping up. Have a look at all the coolant hoses where they connect to the radiator, heater etc and look for any white crystaline deposits where there could be a slight leak. Also at the pressure cap. If you don't find anything major then you could use a leak stopper such as 'Radweld' which wont do any harm. A working temp gauge is pretty much a necessity if you want warning of anything amiss with the engine. If we assume the gauge is ok itself then it gets three inputs . A common 12v supply along with the other gauges , an input from the coolant temp sensor and an earth. 14 pin connector to the combination gauge supplies the temp gauge with earth on pin 8 and sensor input on pin 9. (Assuming Impreza is much the same as the Forester). Sensor itself could be faulty of course .
 

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The expansion bottle is there to allow for the coolant to flow into the bottle when the car is at operating temp. As the engine cools the coolant is sucked back into the radiator. The level in the bottle will vary as outside temps change. In the summer when I check the bottle after a hot drive the expansion bottle is nearly full. In the winter after a longish drive and the car has been at operating temp the bottle is about 1/2 full. Next summer without adding any coolant the level in the bottle will substantially higher than winter levels.

Some friends of mine purchased an 07 new and did not know the function of the expansion bottle. They were filling the bottle when ever it appeared low. As the coolant expanded it would blow coolant out of the bottle all over the engine compartment. When they would pull over it see what was going on they would add more coolant.

Crazy!
 

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2019 Crosstrek 2018 Forester XT
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As the coolant expanded it would blow coolant out of the bottle all over the engine compartment. When they would pull over it see what was going on they would add more coolant.

Crazy!
Some people shouldn't be allowed to drive or procreate.
 
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