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2006 Forester L.L. Bean Automatic
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11 Posts
Discussion Starter · #1 ·
Hi all,

This Forester 2006 is my 1st Susie and I am a little bit confused by the coolant reservoir. When the car has been sitting for a while there is no coolant in the reservoir, but after I drive for a while it reaches to full. No overheating issues, or any coolant leak (that I can see). Is this normal?
 

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2018 X3 M40i / 2016 X3 xDrive35i
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1,632 Posts
Fluid expands with heat. It's not a sealed coolant system so evaporation occurs and over time the reservoir level will drop. I fill up with maybe 8 oz a year of distilled water to account for the evaporation.

On yours though, they are prone to head gaskets so it might be more than just an evap issue.
 

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2006 Forester L.L. Bean Automatic
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11 Posts
Discussion Starter · #3 ·
That makes sense. After I drive a while I can see the fluid at Full line. I just wasn’t aware the thing is completely empty on cold. Head gaskets are ok so far, no leaks on them, no white smoke, no overheating, and as far as I know they’ve never been done in all the car’s life. Keeping fingers crossed of course :)
 

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1999 A/T - 235,000 mi. WA state
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921 Posts
Your expansion is way more than what I experience, or have heard of for any car. Antifreeze expands with heat, water doesn't. And anti-freeze leaks out more than water does, I think. So hopefully maybe your car just has too strong an anti-freeze mix.

Suggest pulling a sample of the coolant and let it come to room temp and then use a freeze point gauge to find the freeze point of your particular coolant mix (~$6 any auto parts store). Freeze reading should be -34F (50:50 antifreeze:distilled water). If it's lower temp than that either drain and refill system, or add distilled water when it's warm and it'll be pulled in and mix over time.

Every store sells pre-mixed 50:50 coolant or 100% coolant, to be diluted before use. It's possible the prior owner just added the 100% jug without knowing he should be adding 50:50.

Luck.
 

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2005 Forester Automatic
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495 Posts
OK, you are in for bad news I fear. When coolant bottle goes from empty to full and the vehicle is not experiencing overheating, the culprit is exhaust gasses.

Run your Foz a little hard, and then stop with it running, preferably in a shaded or indoor location, and shine a light through the coolant overflow bottle. If you see bubbles rising from the hose at the bottom and the temp gauge is not showing hot, then what you are seeing is exhaust gasses.

And your coolant is low, because you are sucking a little coolant into the combustion chamber during your intake stroke. The combustion stroke is forcing gasses into the water jacket.

Head gaskets fail variously, but the Ej can fail such that the water jacket and the combustion chamber communicate. No external leak, but internal. You will eventually need to fix this, or it will first cause the exhaust sensors to fail, then destroy the valves, maybe ruin your catalytic convectors.

If Uhoh is correct then you are a luck soul......

Please do update, regardless....
 

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2007 Forester Sports XT 4EAT
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41,211 Posts
@Redviolinalex lots of opinions on this subject! :icon_eek:

As for me, I want the coolant on the "full" line, when checked cold. Cold means the vehicle has cooled 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. :wink:

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.

Bobby...


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

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Premium Member
‘14 FXTT; '15 Legacy FB25
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1,100 Posts
Coolant and water expand and contract at a similar rate with changing temperature.

If the level changes in your reservoir are consistent and levels are not fluctuating in your radiator, then it's unlikely that exhaust gasses are getting into your coolant.

I too add some distilled water every so often to account for evaporation. Only water evaporates out, carrying little, if any, coolant with it. Adding 50/50 when your reservoir is low is likely fine, since the concentration effect is relatively low, but distilled is cheaper.

OP, add distilled or 50/50 coolant to to fill your reservoir to the full level after the engine has fully cooled-down, just as 2.5x sleeper recommended. If there's an issue you'll see the level lower over a short period of time. If you need to add some more again in 6 months to a year, then it's less likely that you have a problem.
 

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2006 Forester X 4spd auto (4EAT)
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60 Posts
Adding water alone to the expansion tank is a pretty bad idea, at least in northern climates. It will dilute whatever antifreeze is there, then freeze and maybe split the tank. Keep a bottle of 50/50 mix and top up with that. Much safer. I think water evaporating out of AF mix is a pretty farfetched thing to worry about.

It's probably worth investing in a coolant fill funnel kit, which I used a lot more than I thought I would, and avoided spilling AF all over the place while investigating these problems in my Sub.
BG
 

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Premium Member
‘14 FXTT; '15 Legacy FB25
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1,100 Posts
You bring up a good point - I also live in New England.

Easy fix: add distilled on a moderate day, before you drive the vehicle. Unless you have a leak or only check your fluids on frigid days, you should be able to add as-needed, not just on -15F days.
 

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2006 Forester L.L. Bean Automatic
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11 Posts
Discussion Starter · #10 ·
Guys thanks for all the info.

So, when the car is running, the coolant expands to full line precisely. Every time. For months has been like that, more precisely since I got the car in July 2017, driven for about 20k miles until now. So ever since then I noticed this, it's not something new.

If there would be any kind of problem or leak of any kind, wouldn't the coolant get even further down? I'll post tomorrow a photo of cold & hot reservoir.
 

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2006 Forester L.L. Bean Automatic
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Discussion Starter · #11 ·
Guys look what I found on a mechanic's site:

'The coolant reservoir on your Accord is connected to the radiator, and allows coolant to flow back and forth between the two as it heats and cools. If the coolant reservoir is completely empty, you can’t just refill it. You need to check the level of coolant in the radiator as well.'

I wonder if that is the case with Subaru as well and if this is the reason why I see no coolant in reservoir when cold, but when hot is up the full mark
 

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you have a coolant leak somewhere, and air in the system too, wait until cold, remove radiator cap if yours has one, then fill radiator to absolute full, ,then fill overflow reservoir until it reaches the full COLD marks, replace the 2 c
caps start/run until it begins to rise in the overflow, and is fully warmed up............., yes water and coolant both heat up and expand in volume when hotter, . using a strong flashlight , watch cross over and all hoses for leaks, look for coolant /oil leaks on undersides of both heads, watch for gas bubbles in over flow,tank, it may not show overheating due to your sending unit or gauge not working or so much air on the system that a air bubble has lodged at the sending unit - get this checked by a experienced in subaru pro and repaired before you lose the engine

and the plastic tanks on these radiators tend to leak and swell closed when hot, so check tanks sides, bottom/top when warming up too
 

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2006 Forester L.L. Bean Automatic
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11 Posts
Discussion Starter · #13 ·
Update: went to Subaru dealer, then to my own trusted mechanic - no problem with the cooling, system is operating normal, no leaks no nothing. HG are ok, oy leaking part (which I didn't know, because it seems theeak is very very small) is my valve cover gasket on driver side, which I'll change with the next oil change due in 2weeks or so.
Thanks all for input!
 
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