[Atomheart]

2009 Forester X, 190,000 miles. Just bought it used from the original owner, and for the most part it seems to have been very well-maintained.

But there's something odd going on with the cooling system. If I open up the cap after it's been sitting a full day, coolant bubbles out of the top. I bought a new cap, but it still does that. Where could this pressure be coming from, and why is it nor being bled off? I have to confess, I don't know a lot about cooling system problems. I just know how to flush and change thermostats.

I should add, there's no temperature gauge on this car, unfortunately. But the system seems to be operating normally, although there have been a couple of times I thought I might have caught a whiff of coolant after driving, but could never find it. I live in Central Kentucky, so it's been driven on some pretty hot days.

 

[Subyroo]

2009 Forester X, 190,000 miles. Just bought it used from the original owner, and for the most part it seems to have been very well-maintained.

I should add, there's no temperature gauge on this car, unfortunately.

Grab yourself an UltraGauge or a similar type product to monitor the temp.
The UltraGauge has a lot of other gauges available too if you are the type of person who likes to know what is going with your vehicle.

 

[Atomheart]

Now, that's an interesting idea. I may need a week or two to come up with some reason to give my wife for why it's absolutely necessary, but I'll think of something!

 

[DragonSubie7]

@Atomheart -
Although no temperature gauge, you still have a warning light, and after sitting all day, the engine coolant temperature should not be all that warm.
Typically, your overflow tank volume will increase when the engine is warm, and go down as it cools... Does it?
If there is no level change in the overflow tank, the line may be blocked.

Does coolant overflow out of the cap early in the morning when it is cool?
When cool or just warm, there should be little to no pressure in the cooling system.

Overflow out of the cap when cool is more likely to be caused by the cooling system having been pressurized from a failing head gasket.
What does the coolant look like? Is it oily or does it have a film floating on top? That's another sign.

 

[Subyroo]

Now, that's an interesting idea. I may need a week or two to come up with some reason to give my wife for why it's absolutely necessary, but I'll think of something!

Tell you wife it's Insurance money well spent.
Spend a few $'s to save hundreds if not thousands of $'s for a replacement engine if you cook it.

 

[Atomheart]

@Atomheart -
Although no temperature gauge, you still have a warning light, and after sitting all day, the engine coolant temperature should not be all that warm.
Typically, your overflow tank volume will increase when the engine is warm, and go down as it cools... Does it?
If there is no level change in the overflow tank, the line may be blocked.

Does coolant overflow out of the cap early in the morning when it is cool?
When cool or just warm, there should be little to no pressure in the cooling system.

Overflow out of the cap when cool is more likely to be caused by the cooling system having been pressurized from a failing head gasket.
What does the coolant look like? Is it oily or does it have a film floating on top? That's another sign.

The overflow line is clear in both directions (blew from both ends just in case). The overflow tank was almost empty when we bought it a week ago; I have since filled it to the "full" mark. The level in that tank fluctuates between drives, but I haven't had enough data points to accurately evaluate that.

The pressurization problem is intermittent. Since I started this thread 2 days ago, I've had at least 5 drives of 20 miles or more, and 3 of them were over 40. Each time, I've let the car cool down to ambient temperature and checked the pressure; each time, the coolant behaves normally when I popped the cap - no excessive pressure.

There was a very, very slight oil sheen on top of the fluid the first couple of days. It was barely noticeable; you had to be seriously looking for one - but now, I can't detect it. I'm sort of wondering if there was some gunk in the overflow tank that had been contaminated with a little bit of oil or tranny fluid or whatever, and that got sucked in there?

I'm thinking maybe one of two things - maybe the people we bought it from did some work on it before selling it to us (changed the coolant, replaced the thermostat, whatever) and left an air bubble in the system; or - maybe - the overflow tube was blocked, but somehow cleared a couple of days ago.

At any rate, it now seems to be a non-issue. I can't troubleshoot it if I can't replicate it. I really appreciate people making an effort to help me out, and I'm sorry we didn't really get the chance to work it all the way to a resolution. But if it starts happening again, I promise to start whining about it again!

 

[bman400]

Do you have all the service history for this vehicle. Bubbling and oil sheen are signs of engine oil mixing in the with coolant, meaning Head Gaskets are leaking.

1. Coolant level dropping and requires refilling often but no signs of leak stains means coolant is leaking through the head gaskets.

2. Oil level dropping, or signs of oil in coolant are also signs of Head Gasket leaking.

3. White Smoke coming out of the exhaust while engine is warm means coolant has leaked through the head gasket into the combustion chamber and being burnt.

4. Bubbles showing up in coolant are also signs of head gaskets leaking.

 

[DragonSubie7]

@Atomheart - Re: " I really appreciate people making an effort to help me out, and I'm sorry we didn't really get the chance to work it all the way to a resolution."

Lots of helpful folks here... If your problem is resolved, that's a good thing.

It sounds like you have an incomplete car history, and hard to say what may or may not have been done.
If it were me, I'd keep an ongoing eye out for signs of HG problems.
@bman400 noted most of the symptoms you could see.
Head gaskets can cause oil in coolant, but you can also get coolant in the oil, which will need immediate attention or your engine will be toast in short order.

Not to obsess about it, but if you see ongoing or increasing coolant loss, or a rapid change in the way your oil looks, or other signs as pointed out, you will have a big ticket repair on your hands.

If you don't your own maintenance, you may want to establish a relationship with a good independent Subaru repair shop for ongoing maintenance, so when you do need a major repair, you already have a reliable mechanic to deal with, as opposed to "Quicky Lube" or the Subaru "stealership".

 

[Atomheart]

Do you have all the service history for this vehicle. Bubbling and oil sheen are signs of engine oil mixing in the with coolant, meaning Head Gaskets are leaking.

1. Coolant level dropping and requires refilling often but no signs of leak stains means coolant is leaking through the head gaskets.

2. Oil level dropping, or signs of oil in coolant are also signs of Head Gasket leaking.

3. White Smoke coming out of the exhaust while engine is warm means coolant has leaked through the head gasket into the combustion chamber and being burnt.

4. Bubbles showing up in coolant are also signs of head gaskets leaking.

Thanks. I'm familiar with all those things, though, and none of them are happening except the very slight oil sheen. Out of curiosity, I put some clean coolant in a glassbowl and rubbed my fingers together several times in the bowl of coolant. Just doing that alone produced an oil sheen comparable to the one in my radiator. I don't know if it's skin oil or just residual oil on my hands from touching dipsticks and things under the hood, but just that alone gave me a slight slick in the bowl.

None of the other things are happening, which is puzzling. Coolant level is constant, oil level is constant with no sign of coolant, no white smoke, no residue in exhaust pipes, no bubbles in coolant... none of it. Just that intermittent pressure issue and that slight oil slick.

For what it's worth, I popped the radiator cap again this morning after the car had been sitting all night, and it did spit out a few drops of coolant, along with the sound of pressure being released. Not to the degree that it did a few other times earlier this week, but a little bit. I had driven it about 60 miles last night in 90+ degree Kentucky heat before parking it, and then let it sit all night.

I'm kind of leaning toward this being the very early stages of a head gasket. I'll keep a close eye on it, and see if I can spot any kind of trend one way or the other. Maybe do a cooling system flush so I know I'm starting out with pristine pipes, in case someone topped it off with a funnel that had some oil residue in it. I always do that before winter with a newly-bought car anyway. May as well do it now, and throw in a new thermostat while I'm at it.

I do have very good maintenance history on the vehicle. The woman kept almost every single receipt for 10 years, and the Carfax is pretty detailed. You never get everything, though - some receipts always get lost. For example, there's no receipt for a timing belt, and it doesn't show up on Carfax, but there is a dealer sticker showing it done at 106,500 miles. I'm thinking of giving the original owner a call and asking her a few questions about the history. I don't think she'd mind.

 

[Atomheart]

If you don't your own maintenance, you may want to establish a relationship with a good independent Subaru repair shop for ongoing maintenance, so when you do need a major repair, you already have a reliable mechanic to deal with, as opposed to "Quicky Lube" or the Subaru "stealership".

I do as much of the maintenance as I can, but I'm not really a mechanic. Brake jobs are about as far as I go. But there is no "good independent Subaru shop" anywhere near us. We're in Central Kentucky, and even the dealerships here are borderline incompetent. I'm originally from Northern Wisconsin, so most major Subaru-specific repairs I just wait and take care of when I go home to visit family.

 

[Subyroo]

I do as much of the maintenance as I can, but I'm not really a mechanic. Brake jobs are about as far as I go. But there is no "good independent Subaru shop" anywhere near us. We're in Central Kentucky, and even the dealerships here are borderline incompetent. I'm originally from Northern Wisconsin, so most major Subaru-specific repairs I just wait and take care of when I go home to visit family.

Any moisture - water collecting up under the Oil Filler Cap?

Have you replaced the radiator cap with a new one?
If not get an new OEM cap, not a similar type cap sold by a spare parts shop ala Pep Boys etc?

Try the cheap solutions first. :thumbsup: :grin2:

 

[cdherman]

You are on thin ice/borrowed time in another aspect as well. The dealer sticker from 106k miles for the TB. You must assume that the dealer replaced ONLY the TB. That means your waterpump, tensioner and idlers are at 190k miles. You should start looking for a place to do them. Read up on what all needs to be done at the same time (oil pump reseal gets discussed, cam seals? etc). But there is a fairly large consensus that the belt, all the idlers, the tensioner and the waterpump ALL get replaced together (exception WP at 105k miles, but yours is a 190k)

 

[Atomheart]

Any moisture - water collecting up under the Oil Filler Cap?

Have you replaced the radiator cap with a new one?
If not get an new OEM cap, not a similar type cap sold by a spare parts shop ala Pep Boys etc?

Try the cheap solutions first. :thumbsup: :grin2:

No, no moisture under the filler cap. Spotless. I haven't tried an OEM cap yet, but since the Autozone cap had no apparent impact, that's the next step.

I'm also going to get a test kit and check for combustion gases in the coolant. I've never done that before, but from what I understand it's a pretty reliable indicator. 30 or 40 bucks is a small price to pay for peace of mind.

 

[Atomheart]

OK, so... as an update... I picked up a test kit at Autozone today, and checked for combustion gases in the coolant. Ran the test twice, and the result was negative both times. If that test is accurate, then it apparently is not a head gasket.

Next step is the OEM radiator cap, I guess.

 

[Subyroo]

OK, so... as an update... I picked up a test kit at Autozone today, and checked for combustion gases in the coolant. Ran the test twice, and the result was negative both times. If that test is accurate, then it apparently is not a head gasket.

Next step is the OEM radiator cap, I guess.

Cheapest option at this point. :thumbsup:

 

[Atomheart]

Cheapest option at this point. :thumbsup:

Seems to be the only option, or at least the only one I can think of. Auto Parts Store Guy suggested the PCV valve; at 190K, it wouldn't hurt to replace that anyway, I guess.

I can't help wondering if there's any way the thermostat could be causing this... I guess I'm just grasping at straws now.

 

[Subyroo]

Seems to be the only option, or at least the only one I can think of. Auto Parts Store Guy suggested the PCV valve; at 190K, it wouldn't hurt to replace that anyway, I guess.

I can't help wondering if there's any way the thermostat could be causing this... I guess I'm just grasping at straws now.

Could well be, I have heard of non OEM thermostats causing owners grief.

The PCV valve routes air and fuel from the crankcase back through the intake manifold to the cylinders, rather than allowing them to escape into the atmosphere. I can't see how that would affect the pressure in the cooling system because it is a totally separate system in itself.

 

[RyanT]

How did the OEM rad cap work out? Its not going to be the thermostat or PCV valve.

 

[bman400]

Doubt it's the PCV valve. My 2001 with 215,000 miles is still on the original factory PCV valve. The PCV system is completely separate from the Cooling System and it's only job is to suck in crankcase fumes to be burnt in the engine instead of the engine dumping that stuff into the atmosphere. If that is not working as in plugged, you would potentially have oil leaks in the crankcase, etc....due to fumes building up pressure. Or you would have a leak there and that leak would cause you a major vacuum leak on the intake system of your engine.

 

[Subyroo]

You are on thin ice/borrowed time in another aspect as well. The dealer sticker from 106k miles for the TB. You must assume that the dealer replaced ONLY the TB. That means your waterpump, tensioner and idlers are at 190k miles. You should start looking for a place to do them. Read up on what all needs to be done at the same time (oil pump reseal gets discussed, cam seals? etc). But there is a fairly large consensus that the belt, all the idlers, the tensioner and the waterpump ALL get replaced together (exception WP at 105k miles, but yours is a 190k)

This is what was replaced on my 2003 XS Forester 5MT at when I owned it:

100,000km Service - Cam Shaft Timing Belt, Top Rad. Hose, Thermostat O-Ring, Crankshaft Front Seal, Neutral Switch.

200,000Km Service - Timing Belt - Crankshaft Front Seal - Timing Belt Idler Pulley - 2 x Camshaft Seals - No. 1 and 3 Spark Plug Leads - Gear Linkage Coupling - Neutral Switch.

It was still running solid at 224,781 Kms when my took over ownership on 07 May 2013 and she had it for about another 70,000 kms before she sold it. She had to replace the OEM suspension on the front because 1 of the struts had a minor leak, the rear struts were still original.

The young guy who bought still has the forester to this day, he does Pizza deliveries in it, so the kms would be getting fairly close too or over 500,000 kms by now.