2017 - Coolant level very low - where is the fluid going?

6170 Views 19 Replies 14 Participants Last post by whobodym, 1 d ago

kallsop

Discussion Starter · Dec 31, 2020

2017 Forester 2.5i. I don't recall how long ago, but likely more than a year ago, I noticed the coolant level was down a bit and topped it off. (Pentofrost
A3, the blue stuff, 50/50 premixed).

Went to add windshield washer fluid this week and also checked the coolant level - not only below Low, but really low! Topped off to Full mark. I last checked the fluid level about 3 months ago at the last oil change. The car is driven gently.

This is a sealed system. Where is the fluid going? There is no noticeable leak. The car is running fine, normal mpg, etc. The car now has about 65,000 miles and is covered by 7/100 Subaru warranty.

What to do? Could there be a small slow leak that will not worsen? Is this typical for Subaru flat engines? Obviously I don't want to wait until the car passes the 7/100 warranty period if this needs attention. I will check the fluid level again this weekend.

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scoopburt

· #2 · Dec 31, 2020

QUOTE "The car now has about 65,000 miles and is covered by 7/100 Subaru warranty."

Be happy it's under warranty and that the car in. The coolant is going somewhere. Best case leaking hose. Worst case head gasket. Have it checked. That's what the warrenty is for. Leaks never get better. Let us know what you find. Thanks

Sent from my SM-G965U using Tapatalk

whobodym

· #3 · Dec 31, 2020

kallsop said:
2017 Forester 2.5i. I don't recall how long ago, but likely more than a year ago, I noticed the coolant level was down a bit and topped it off. (Pentofrost
A3, the blue stuff, 50/50 premixed).

Went to add windshield washer fluid this week and also checked the coolant level - not only below Low, but really low! Topped off to Full mark. I last checked the fluid level about 3 months ago at the last oil change. The car is driven gently.

This is a sealed system. Where is the fluid going? There is no noticeable leak. The car is running fine, normal mpg, etc. The car now has about 65,000 miles and is covered by 7/100 Subaru warranty.

What to do? Could there be a small slow leak that will not worsen? Is this typical for Subaru flat engines? Obviously I don't want to wait until the car passes the 7/100 warranty period if this needs attention. I will check the fluid level again this weekend.

but was the radiator itself below completely full? (check this only when the radiator and engine are truly cold) the overflow container (location of the max and min marks) is pretty small, so you will want to know the total coolant loss volume, not just from the bottle. an already-serious problem would show you a low radiator level too. my own experience with multiple VWs, Hondas, Mazdas, Nissans is that all cars drop their coolant bottle levels by a fraction of an inch over a year or so. are you making your observations at consistent engine temperatures? a fully-warmed-up engine can have the level 2 inches or so above the cold level because of thermal expansion. are you smelling any funny smells from either the heater, under the hood, or from the exhaust? does the motor oil look normal? I agree from what you've said so far that you may have a problem, but if all my other specific questions don't have alarming answers, I bet you've luckily and smartly caught your problem at a very early point. maybe something simple and cheap like a pinhole in a radiator hose??

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Reactions: 3

1982

· #4 · Dec 31, 2020

On my 2017 a minor leak in the radiator cap produced the same results. Cap replaced, problem solved.

Reactions: 1

Easy Fixer

· #5 · Dec 31, 2020

Have the cooling system pressure check to 15PSI. With the engine cold open the radiator cap and see if there is air. It should be full to the radiator cap.

Botnik

· #6 · Dec 31, 2020

In other posts I've read that the Subaru Super Coolant is made to be easier on the head-gasket material than standard coolants, because the head gaskets in a horizontally-opposed engine are in contact with the coolant all the time. I don't know if use of another coolant with contents that are harder on the head gaskets would cause a leak in such a new car though.

CGumina

· #7 · Dec 31, 2020

For the record, most cooling systems are "closed loop" except for the expansion tank. The expansion tank, by nature, cannot be fully sealed because fluid displaces air in the tank. Since most coolants are a 50/50 mix of distilled water and antifreeze, it's not impossible to think that the distilled water may be evaporating slightly. Unless you're emptying the overflow every 3 months, I wouldn't really panic.

I typically have to top off all of my vehicles once a year or so with a touch of coolant. Nature of the beast.

Reactions: 2

kallsop

Discussion Starter · #8 · Dec 31, 2020

I checked the level this morning, and it is right where I filled it to on Monday, just a hair below the full line. The radiator is full. I'll check the expansion tank level at every gas fillup. The only work done to the car this year was by the dealer, replaced the leaking A/C condenser. I wonder if they had to drain coolant and refill, and got air in there?

sneefy

· #9 · Dec 31, 2020

kallsop said:
This is a sealed system.

Nope.

Reactions: 3

DragonSubie7

· #10 · Dec 31, 2020

I've never owned a Subaru that never needed coolant added occasionally.
In addition to the minimal losses due to normal engine operation, when it gets hot there is also loss from evaporation as the humidified coolant air is expelled from the overflow. Also, an overflow tank that is filled to the max line on a warm day will be lower the next morning when it is very cold.
Liquids expand and contract with temperature.
Chances are, it was "just a bit" warmer 3 months ago in Connecticut....

Reactions: 1

bman400

· #11 · Dec 31, 2020

My Mercedes ML 350 Blue is a truly sealed system and the Subaru's are not a sealed system. On the Mercedes there is no radiator pressure cap. The only pressurized cap is on the overflow bottle, there are warnings in the owners manual and on the overflow bottle cap, "DO NOT Open unless engine has cooled below 80F!". The overflow bottle of the Subaru is not sealed in anyway and allows fluid to evaporate over time. If the Subaru was a sealed system, then there would be a pressurized cap on the overflow bottle as well.

Reactions: 3

panixgr

· #12 · Jan 2, 2021

@bman400 same thing with our hyundai i20, closed system.

Reactions: 1

whobodym

· #13 · Jan 2, 2021

bman400 said:
My Mercedes ML 350 Blue is a truly sealed system and the Subaru's are not a sealed system. On the Mercedes there is no radiator pressure cap. The only pressurized cap is on the overflow bottle, there are warnings in the owners manual and on the overflow bottle cap, "DO NOT Open unless engine has cooled below 80F!". The overflow bottle of the Subaru is not sealed in anyway and allows fluid to evaporate over time. If the Subaru was a sealed system, then there would be a pressurized cap on the overflow bottle as well.

My Audi (and I think lots of VWs) also has a pressurized coolant reservoir, unlike our Forester. But I have to add not-dissimilar small amounts of coolant to both, perhaps once per year.

Reactions: 1

bman400

· #14 · Jan 2, 2021

whobodym said:
My Audi (and I think lots of VWs) also has a pressurized coolant reservoir, unlike our Forester. But I have to add not-dissimilar small amounts of coolant to both, perhaps once per year.

Interesting, I am doing the same with my Mercedes, on an annual basis in the fall season adding coolant to it as well. Makes me wonder where it is disappearing to? I can't find a leak stains anywhere. But that's for a different forum altogether.

Da More-ster

· #15 · Jan 2, 2021

I know the Subaru super coolant is the OEM recommendation but at $35 a bottle from the parts department what would you guys recommend for an over the counter alternative?

whobodym

· #16 · Jan 2, 2021

bman400 said:
Interesting, I am doing the same with my Mercedes, on an annual basis in the fall season adding coolant to it as well. Makes me wonder where it is disappearing to? I can't find a leak stains anywhere. But that's for a different forum altogether.

just because the cap is pressurized doesn't mean that occasionally the pressure doesn't reach the threshold and release a burp or two -- just my speculation

Reactions: 1

DragonSubie7

· #17 · Jan 4, 2021

The level of coolant observed in any system will change due to ambient temperature. If it's exactly full on a hot day, when checked on a cold morning it will be lower.
The reason for an expansion tank is because the coolant fluid expands when heated and contracts when chilled.

Reactions: 3

Scooby24

· #18 · Jan 4, 2021

It evaporates. Top off with distilled water. Should need a top off once a year or so. Dealerships normally do this for your when you bring it in for service so most people don't realize their new vehicles are getting topped off with coolant.

erinincolorado

· #19 · 1 d ago

kallsop did you ever figure out the problem? My partner has the same exact car but it's 2018 and is having a problem with coolant burning off but not visibly leaking anywhere. He took it back to the dealer and they told him that it was likely evaporation but it was way too much loss for that explanation to make sense. By that I mean, he saw the coolant was low not even 30 days after buying the car. So, the same day he discovered it, he bought new coolant and filled it up to the line, but the very next day it was low again. Not empty, but too low to account for "evaporation." We're fearing the coolant is leaking into the engine and the dealership isn't being forthright (they said they "tested the car all day" and found no issue). He's talking it to an expert Subaru mechanic across town for a second opinion now.

whobodym

· #20 · 1 d ago

@erinincolorado - it is possible, if coolant has been recently flushed and then replaced too carelessly, to not get all of the trapped air back out of the cooling system at first. So if that was done to your partner's car, and the loss of coolant you've seen since then means only for a few days, and only being refilled a few times, yes everything could be OK. The coolant loss you perceive should quickly diminish to nearly nothing as the bubbles work their way out. However, if the car has been driven thousands of miles and many weeks and the loss still is happening at the same rate, you have some other problem definitely. My Forester's coolant reservoir level its whole life has gone down no more than 1/2-1 inch in an entire year, driving about 15,000 miles per year. Week after week, checking under the hood, it seems to stay the same.

Reactions: 2

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