[Performance Suby]

Water pumps arn't usually a problem, thats not say it is a possibility. I still have my original water pump at 125K. If your headgaskets are not leaking coolant externally, which I doubt since you've already had them done then I don't think they would be the issue either. Coolant level dropping in the reservoir slightly is normal, due to evaporation.

My initial guess would be to replace the thermostat with a genuine Subaru one, especially if you still have the original one or if it has been replaced with an aftermarket one (they are problematic on Subaru's) and it isn't very expensive either. 50/50 coolant is the best to use. See if that helps.

 

[subiesailor]

HG - replacement and the skilled hands that do them matter. So HG replacement doesn't mean your trouble free if the hands that did it lacked the skill to do it right. However the 2000-2002 HG leak was external coolant dripping out of the head. Most common side was driver side. Easy way to take a quick peek is right after running the car long enough to get it warmed up etc - not hot just running warm - crank the wheels hard right, park the car and take a look from just behind the driver side front wheel looking forward at the bottom back corner of the engine. The HG leak will drip coolant onto the hot exhaust evaporating all evidence after just a few minutes of being parked. Part of the reason people had a hard time sorting out they had a coolant leak given they didn't have the puddles of coolant under the car etc.

Do that first - no signs of a wet engine or dripping coolant then your probably OK regarding HG issues. The next step as posted above Subaru only tstat given the cheaper after market one's have a long history of causing subaru owners lots of heart burn and funny engine temps.

Some other little things to eye ball. If the over flow hose or the nipple at the radiator is split the cooling system will suck air back into the system and cause issues. The other little thing about that over flow hose in the bottle if its a tad long and cut square across the bottom it can suck its self to the bottom of the over flow bottle and prevent coolant from being drawn back into the system so if its cut strait across you could simply take a pair of snips and cut it at 45 degrees to remove it from the list of possible issues.

Try those first.

Burp the cooling system - take the cap off when the car is cool - run it for a bit so the cooling system opens up and top off the radiator if it needs it. Let it idle for 5-10 minutes once its warm to make sure you work all the air that could be caught in the system. This might by its self get rid of your issue.

 

[subiesailor]

Don't discount that your Radiator if original could be blocked up either internally or have much of its cooling capacity diminished simply by years of road grime packed into the radiator fins. It happens.

Turn your AC on and make sure your fans are running - however your description doesn't sound like a failed fan. But never hurts to take a peek.

 

[Ghetto]

Well...My thought is probably headgaskets. When they are replaced the heads and block, where the gasket touches, need to be squeaky clean. If there was any dirt, oil, or oxidization that was not removed, that could be a problem. If contaminates were removed with sandpaper or a wire brush and those areas got scratched, that could be a problem. I have done a lot of HG's and I get the heads resurfaced every time. Every set of heads I have taken in have had 4 thousands of an inch taken off to get them flat again. Every time the exhaust side of the heads is the lowest point. After 125k miles I am sure that your heads are 4 thousans off as well.
I hope I am wrong. It could still be something else. If you do have to re-do the HG's I strongly recommend getting your heads resurfaced. It only costs me $60 and usualy only takes 1 hour. Also do some research when choosing your HG's. I swear by Fel-Pro Perma-Torque MLS.
+1 on using a Subaru T-Stat. Maybe you need a new radiator cap. If so, use a Subaru Radiator cap, not aftermarket.

 

[crhawkeye]

Thanks for the feedback everyone.

Am losing coolant at a decent rate out of the reservoir, so something is amiss. (although it's always been benign when I had that problem before)

Just never noticed the heat issue... (so while it could be a t-stat and diff issue with coolant leak...doubting it)

Will try the behind the wheel check tonight. Did that when I initially noticed I was losing coolant a half year ago... but it turned out to be hose related.

Don't know much about the preventative headgasket fix and what parts they used... other than the work is now out of warranty

Still not convinced it's headgasket problem... we'll see though.

Want to take this thing cross country in about 3-4 weeks.

 

[subiesailor]

I had a 2001 - cooling system in this generation is not very robust to start with so anything even minor like really gummed up radiator can cause the temp to spike given the right driving conditions. So don't discount little things that look minor. The coolant loss aspect for sure needs to be sorted out. We took ours on a 2500 mile road trip at 156,000 miles - ran like a champ zero issues HG driver side was replaced by Subaru at 65K. Just one of those things older car it might need some snooping to spot leaks etc.

 

[crhawkeye]

So I did the crank the wheels right test and saw nothing dripping down onto exhaust. Nothing hitting the ground. May or may not have caught a whiff of it upon opening my door.

Really sniffed around the vents for any smell from a heater core issue...wasn't getting anything. Thought maybe the heat was running a little bit more moist than normal. But maybe I'm imagining things. Cool air worked fine.

Not sure what to do next other than a leak down...

 

[crhawkeye]

So I had a pressure test on the cooling system.

They ran it for a few hours, I believe, and found nothing. Fun.

His suggestion was to start with the thermostat and then go for a system flush.

Of course they didn't have an explanation as to where the coolant was going from my reservoir. I know I'm not imagining things there.

He thought that an external gasket leak or heater core problems would be caught by the pressure test. (I know if I want real assurance on head-gaskets I could run a compression test)

Soooo... any bright ideas? Over the last few months I lost a few inches out of my reservoir... and then recently began noticing issues with thermostat running higher after a period of time. (and it being resolved with turning on the heat in the car)

Coincidence that this all started at onset of cold weather? (probably)

 

[crhawkeye]

Reading what I just said... this does sound a bit ominous.

 

[crhawkeye]

So tonight I popped the hood and left it running while I looked around. I noticed under the sticker on the radiator cap a little bubble with a bit of coolant. That's obviously not good. Could it be the cap? I also noticed a few greasy spots near the radiator cap on hoses... I wonder if I've got pressure issues there?

Bought a new cap, put it on. Drove 10 or so minutes to someones place and no signs of the thermostat going up.

Fast forward a few hours...

Cold front passes and it's freezing out again, had been a nice day near 50. Start driving back... get about 10 minutes in without running heat and the temp starts raising... let it go near 3/4... open up the heat vents, it drops. Do this repeatedly on my half hour drive home. As soon as I turn on the heat it goes back to its regular 1/2 range and stays there.

So this is interesting. I've only noticed this behavior in really cold weather. And turning on the heater always fixes it.

Still not seeing any sign of leaks aside from the noted cap weirdness.

Could it be that the cap weirdness somehow led to a compromised thermostat and or other problems? I guess the thermostat would be my next shot.

 

[1 Lucky Texan]

the tiny aftermarket t'stats, coupled with the low-front t'stat position, seems to cause problems with them closing when they shouldn't.

or, it's a worn-out original t'stat.

bet an OEM-style t'stat will fix it. hope so anyway.

 

[Ghetto]

+1 on using a Subaru T-Stat. Maybe you need a new radiator cap. If so, use a Subaru Radiator cap, not aftermarket.

Are you still losing coolant?
You could take the radiator cap off, make sure the radiator is topped off. Then start the car and look at the radiator while slowly raising the rpm. Look for bubbles coming out of the coolant. If so, HG for sure.

 

[crhawkeye]

Did find coolant leak finally. Underside, collecting on tray of sorts...dripping down... near axle/exhaust pipe... can't see it's origin though. Also some drops on the lower radiator hose... though again... not sure where origin of leak is.

Exhaust is a bit wet, not sure if it's always like this. Leaving some spots of moisture on the ground when parked... doesn't smell like coolant though. Doesn't have much of a smell.

The leak before mentioned was only found after driving (not quite up to full heat) and parking on a bit of a hill... wasn't able to replicate it again, though. Was an easily seen drip coming down and a nice little stain on the pavement. Quite obvious.

Fun fun.

 

[cardoc]

Coolant near the exhaust could be a heater hose, driver side just to the back side of the engine block both hook up to the bypass pipe. Then you have the bypass hose for the throttle body. The crossover manifold itself just uses an o-ring on each side for a seal and they sometimes leak. Other than that, HG. Unless your heater core is leaking, but you would smell the coolant inside the car.

 

[crhawkeye]

Coolant near the exhaust could be a heater hose, driver side just to the back side of the engine block both hook up to the bypass pipe. Then you have the bypass hose for the throttle body. The crossover manifold itself just uses an o-ring on each side for a seal and they sometimes leak. Other than that, HG. Unless your heater core is leaking, but you would smell the coolant inside the car.

Wouldn't put it past this vehicle to be leaking from a hose again. I've already had a few hose problems that led to coolant leaks. As far as I know I've still got all the original items with the cooling system. (radiator,waterpump,hoses etc) Although this one seems to be coinciding with (heading towards) overheating.

Here's hoping it's not a HG problem.

Does seem interesting that the leak, seemingly, is only occurring in the period before the car is fully warmed up. In my testing before I had always driven longer periods of time... today I was only driving a couple of minutes and the vehicle hadn't been able to fully warm up.

Have an appointment with a subaru shop 30 miles away on Monday... at least I found out before the visit. (although given what I've discovered I may try to get some local mechanics to look at it first)

 

[cardoc]

"Also some drops on the lower radiator hose... though again... not sure where origin of leak is."

If this isn't the hose, it could be the thermostat seal or water pump. I noticed this again this morning in the e-mail.

 

[crhawkeye]

And the mystery deepens.

Took it into an independent mechanic that works on Subaru and other imports.

He took it in cold, put it on a hoist, ran it for half an hour. No leaks. Did pressure test. No leaks found. Said hoses and everything looked good.

Checked around the gaskets... nothing externally he saw. Said there was a slightly wet spot by one of the gaskets, but it wasn't coolant. (might've been oil, or moisture of another sort) Really downplayed that as the reason for anything.

His advice was to keep driving and watching for now.

I still need to run the vehicle with the cap off the radiator, checking for bubbles and coolant flow. But I figure given that A) I've lost a decent amount of coolant over a few months and seen a leak, and B) not found any internal gasket failures signs... that it probably isn't an internal failure.

I'm just wondering why I found the leak the day I did and why mechanics couldn't nail it. Surely it must be an odd conditional thing... but one encountered often enough for me to lose coolant. And, I'm assuming, for it to affect the thermostat. (unless these are bizarrely unrelated and I have a bad thermostat + something else weird)

This car did get new head-gaskets 9 months ago... so while that doesn't rule out the head gasket problem totally, it does look somewhat doubtful to me.

P.S. . . . do know what leaking coolant looks like and smells like. And I certainly found it last week... the only time during this episode I've gotten some real evidence. Guess I'll have to try to re-create that event. (perhaps parking on a hill -- albeit, a slight one -- is part of the bizarre equation.

(although, looking back, another bizarre factoid is that after having discovered the leak, I drove it around a few more minutes, came back to the same spot, parked in the opposite direction on the hill, and checked again... no leaking then...)

 

[crhawkeye]

Update:

Bro in law who is a mechanic looked at the thermostat housing area and saw a puddle of coolant that had collected near it.

Couldn't give a definitive diagnosis but thought that it could be faulty housing.

Will have it looked at soon.

 

[crhawkeye]

Flash forward: Ended up having external headgaskets done.

Everything behaved pretty well until this winter. I've smelled coolant a few times and again I saw the thermostat nose up past where it should be. Again I turned the heat on and spike went back down.

My mechanic seemed to do everything right with the gaskets he replaced. I can't believe I'd have head gaskets go bad in under a year. He replaced the entire set.

Is there some other odd problem behind this? I'm beginning to worry now that I didn't need gaskets done in the first place. This car has had them done twice within 3 years now. (first repair I wasn't a part of -- supposedly just did them preventatively)

What the ****... I'll take it in again here, but this is silly.