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Slow Decrease in Car's Engine Coolant

N

npowell

Member
Have a 2013 Subaru Forester with 21K miles. Coolant level in overflow tank is now just below the low mark. Far as I can tell, it has dropped gradually to this level.

Could it have just evaporated? I have heard some say it can. Others seem to say not possible; that there must be a leak or a leaky head gasket.

Welcome your thoughts/experiences.

Thanks,

Neil
 
Unless the engine is severely and continuously overheated coolant simply won't "evaporate". Rather there's a very small leak somewhere in the system. And likely it's leaking only when the engine is at operating temperature so the cooling system is under pressure.

My wife's '03 Chevy Impala would lose about 12 oz of coolant a month. But I couldn't find a visible leak. Finally after a couple years of adding coolant every couple months it began leaking enough to leave a few drops on the floor of the garage when parked. Turned out a plastic elbow for the heater supply hose connection at the water pump was slowly failing. But it only leaked when the engine was hot - the escaping coolant got blown away rather than dripping onto the floor. Replacing the elbow finally corrected the problem - no leaks since.
 
You have a leak. Either find it and fix it, or simply keep an eye on it. Stop leak is an option, some cars come with stop leak from the factory.
 
I have 2 Ford vehicles that I have never been able to keep the overflow tank full. However, once the tank is empty, the radiator stays full and they never overheat. I think the coolant gets blown out the overflow.
 
It should not be loosing coolant.

There is either a leak or the cap is not sealing.

After it had been driven several miles, and is completely warmed up, the system should have pressured up. You should be able to squeeze the radiator hose and feel the firm pressure. If there is no pressure, the cap is bad.

If there is pressure, that is the time to look for a leak. It will probably be a very small leak, could be difficult to find. Look around all visible fittings, the water pump weep hole, radiator seams, etc. A leaking heater core will usually show up as wet carpet or unusual steaming of the windshield. It could even be a leak above the liquid level, leaking only steam vapor.

There is always a possibility it could be a head gasket. But unless the engine has been hot, that is not a real likely cause.

Probably going to find a loose hose clamp. As new as it is, and low mileage, not likely it is anything deteriorated from heat or age.
 

You can do a sniff test--coolant gives off a sugary, sweet smell. With bigger leaks it's obvious just walking by the car--you can detect it. Maybe your leak is not big enough yet. You can monitor and if it gets worse the repair shop can do a pressure test of the system to find out where the leak is. They hook a gizmo onto the radiator and see if the pressure drops and by how much.
 
Not to scare you or anything. We had a car that the coolant light would come on around every 1000 couldnt find a leak anywhere. WE would pressure test and nothing. So i decided to get the car hot. Unplugged the fans cut off the air flow and got it hot. after the cool down noticed the coolant was a little low. I figured head gaskets .So we got a combustion leak detector . and confirmed it. Took the heads off gaskets looked great. I was feeling around in the sleeves and noticed i could feel something come to find out the cylinder wall was cracked .What it was doing was only opening up and loosing coolant when the car was hot while driving. Sure was a crazy find but we found it.
 
I would try putting some Bar's stop leak in it. I had a vehicle once that started dripping a little as soon as it was off warranty, put some stop leak in it and never had another leak. All you have to loose is a few bucks.
 
Thanks for the link. Generally aware of Subaru's history of head gasket problems. In 2011, they introduced a new engine-the FB25, which is in my car. As I think about it, IIRC, this engine does not route any
coolant through the head gasket at the interface between the head and the block. Instead, it has dedicated parallel passages that direct coolant between the head and the block. As far as I know, the jury is still
out as to whether that fixed their head gasket problems.
 
Gentlemen,

Thanks for all the responses. Sounds unanimous that there is some problem, be it small or big. Glad I asked. The powertrain is still under warranty for a few more months. So, probably time to call the dealer......

Neil
 
(quoted from post at 19:10:09 05/22/17) Gentlemen,

Thanks for all the responses. Sounds unanimous that there is some problem, be it small or big. Glad I asked. The powertrain is still under warranty for a few more months. So, probably time to call the dealer......

Neil
Click to expand...

The engine has also an issue with oil consumption. Tell the dealer that you have increasing oil consumption as well as coolant loss. They will likely NEVER do anything for you unless you take it in more than 3 times for the same thing.

One thing you can try is to remove the spark plugs and look for one that is different color, or cleaner than the others. This would indicate water in the combustion chamber. Also, if you want to keep working on it yourself, get a pressure tester, and put it under 12Lbs pressure when the engine is fully warm. If you have a leak, it'll go down faster, and then you can try to find it by the dipstick(milky), or turn the engine by hand and see if it is hydrolocked. Don't use the starter or you can bend a rod if there's leaking into a cyl.

Get it looked at before it gets worse. Make subaru do something even if it takes 3 trips or more.
 
Thanks, doc. I will push on the coolant issue.

As for the oil-consumption, it sounds to me like Subaru doesn't have a fix. On that one, I believe I'd rather keep topping it off than go through the hassle of having them look at it numerous times with no real fix.
 
There are two different types of Antifreeze. one is a green color witch it is for all metal radiators. Then there is one that is a orange looking color and that is for the plastic top Radiators. What I learn some time ago was that if you use the wrong type it will take that plastic top radiator apart threw time. Always make Shure that you put the right stuff in your car.
 
I had a 1999 outback, did the same thing... It was the head gasket had it done and sold it. Don't remember how much that was but it was a lot.

Got a 2004 outback, same thing at about 150k, did the head gasket and other engine work for $2k. Drove it for three months had the radiator blow and over heat and blow the head gasket again! Junked the car

Now driving a 2014 outback, guy at the dealership says Subaru completely re designed the engine to solve the head gasket problem. Bought it used with a warranty that includes head gasket for life as long as it's serviced regularly by the dealer... Figure it's cheaper than paying $2k every few years.
 
Thanks. Definitely keep the right kind of antifreeze in it. Currently, it's all the factory fill.

Also, apparently, there are at least 3 kinds of antifreeze. This is blue/purple. Owner's Manual calls it Subaru Super Coolant. Replacement interval is 11 years. Says if it is mixed with anything else, it will no longer go 11 years.
 
Simple test for blown head gasket. Take the overflow hose loose and stick it in a glass of water. Start engine. Bubbles- bad, no bubbles- good. I am the inventor of this method.
 
The top of the radiator is not metal. Looks like it but is plastic. My 2004 Forester did same thing. Leaks come out of the top plastic of the radiator but you can't see it. May occasionally smell it as you walk by but you won't see it. One way to tell, look at the radiator top. In front of the top is a spongy material. It will be wet when you pull it away from the plastic top. It leaks where the metal cores fasten on to the plastic top. You won't see much because it evaporates quickly. $130 radiator online. several good youtube shows on how to replace. About 4 hr simple job if you piddle around. Stopleak works for about 2 days. Fix it very soon before engine overheats.
 
I'd get some of the proper coolant from Subaru and fill it up and keep an eye on it. If it has never been topped off and is just now below the low mark I would not get too worried yet. It may of never been much above there from the beginning.
My sister had one of those the exact same year and model. Hers was an oil burner ! She was going to get the engine swapped out but got a good deal trading it in on the same model but 3 years newer. There is a class action on the engines for burning oil.
 
When I first read it I thought it said 211K, not 21K.

I would keep it full, document the amount and date coolant is added. I would also send an oil sample off to Blackstone labs ( http://www.blackstone-labs.com/ ). Two reasons - it will tell you if your coolant is going into the engine and it MIGHT give you an inkling as why your oil consumption is out of line. If the coolant is going into your engine with enough yelling you might get a new engine out of the deal (that's where I would start) instead of allowing them to swap a head gasket.
 
When I first read it I thought it said 211K, not 21K.

I would keep it full, document the amount and date coolant is added. I would also send an oil sample off to Blackstone labs ( http://www.blackstone-labs.com/ ). Two reasons - it will tell you if your coolant is going into the engine and it MIGHT give you an inkling as why your oil consumption is out of line. If the coolant is going into your engine with enough yelling you might get a new engine out of the deal (that's where I would start) instead of allowing them to swap a head gasket.
 
I don't see where he has an oil burning issue ( yet ) I and others brought it up because that model and year is known to do that ,but not all of them do either.
 
(quoted from post at 07:20:54 05/23/17) There is no evaporation - it is leaking somewhere.
Click to expand...

There are also a couple of coolant dye kits out there that you can try. Google 'coolant dye test' and should be able to find one, or try your local Napa. The dye is a UV liquid, and then you'll need the right kind of light to check it. I suspect doing the test in the dark with the UV light source would be best. Might even see a light ring around the tailpipe if the leak is into the combustion area, and you run it for a while with the dye in solution.

Pressure test first, and if still no luck, then try the dye, but DON'T tell the dealer you used the dye kit as it's likely not covered by warranty. I'd just keep taking it to the dealer since you have the engine covered. This will also document your case should it fail later after warranty, and you want a discount from the dealer. Coolant leaks are not catastrophic, they grow, and get worse over time.
 
(quoted from post at 19:29:24 05/22/17)
As for the oil-consumption, it sounds to me like Subaru doesn't have a fix. On that one, I believe I'd rather keep topping it off than go through the hassle of having them look at it numerous times with no real fix.
Click to expand...

Without going through all of the class action stuff in the lawsuit, the bottom line is the oil consumption limit is 1/3 quart within 1200 miles. Which is a LOT of oil consumption for a modern engine.
 
Good to know. I'd say my oil consumption is right about that - 1/3 qt/1200 miles. That part doesn't bother me so much. But if it's another symptom of the same problem causing the coolant drop, I'll keep track of
that, too.
 
The leak will probably be difficult if not impossible to find until it gets much worse.

You're not seeing drips or wet spots because the amount of leakage is small and it is somewhere on the engine where it is warm enough to evaporate/boil the coolant off quickly.
 
A quart low at 3500 miles isn't terrible, but its not that great either. Are you changing at 3500 miles?



Early warranty books: the Subaru maintenance schedule note #1 reads "When the vehicle is used under severe driving conditions, the engine oil and filter should be changed every 3,750 miles or 3 3/4 months. All turbo-charges vehicles are considered to be operated under severe driving conditions"


Later warranty books: the statement no longer includes "All turbo-charges vehicles are considered to be operated under severe driving conditions".



You need to read your manual on what constitutes "severe driving conditions". You'll probably find driving it anywhere on the North American continent constitutes "severe driving conditions".
 
That is bad advice at best. Any sort of stop leak is BAD. It will plug up radiators and heater cores. On most cars made in the last 15 years or so, it is easier to pull the engine than the heater core.

My policy is to NEVER use stop leak. No matter whose name is on the can.
 
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