'99 Legacy Outback 2.5L - where is the thermostat?

sometime in the recent past Wilson posted this:

Never mind - it is on the bottom. Now that I've replaced the old thermostat with a new one and tested the old one to see that it opened at the proper temperature, I've got to find out why it occasionally overheats. I'm thinking I may have a small leak in the system that's letting the coolant get low.

Headgaskets are always a suspect but sometimes improper filling of the system, bad radiator caps and other less likely issues can also cause odd coolant loss. You should search for 'burping' 'purging' and 'air bubbl' in conjunction with coolant filling as well as 'bad headgaskets'.

carl

Thanks Carl. After cooling down last night, I started the car this morning and managed to get 3 qts. drained which is a little less than 1/2 of the coolant. Then I added 2 qts. & 1 pt. of antifreeze & drove 12 miles one way to town and back. All the way the temp gauge would run up to hot and then drop back to normal.

When I got home, the reservoir was full of green fluid, but it's temp was cool. Finding it cool and probably a couple of minutes later, I jiggled the rad. cap and found that I could remove it. I began to add the rest of the 3 qts. of AF, but the volume in the radiator began to expand, so I recapped it. That's when I noticed that the reservoir was being sucked back into the radiator and the return radiator hose had collapsed as I heard the gurgling/sucking sounds. So I added the remainder of the original 3 qts. of AF fluid to the reservoir. Thinking it might suck even more from it, I topped off the reservoir with some 50/50 AF & water I had mixed up from before.

I had only two thoughts left since my oil cap is clean (no water & oil cream deposits) I figured my head gasket was okay (compression test at dealers last fall was okay.) I'm left with purging a bubble in the system and a weak radiator cap. I was surprised to find the reservoir tank cool since it was empty when I started out this morning.

What symptoms does a weak radiator cap present? TIA

I'm no expert, but nowadays they serve really 3 related purposes. To keep some pressure in the system to raise the boiling point of the coolant mix BUT allow for fluid expansion. The little disc in the center of the cap allows for contraction on cooling and lets fluid back into the radiator from the overflow tank. Of course, some part of that system can be non-functioning and cause varoius problems. The rubber gasketing on the cap can crack, the o'flow bottle can leak or the small hose going to it can be blocked, etc.

I HOPE you only have a bubble or air. But some 99s have internal leakage ($$$$) IIRC and others may have external leakage (hassle to $ to $$$$).

watching the o'flow bottle can sometimes be your best guide.(it can sometimes take 2-3 'drive cycles' - with overnight cooling to really get the air out) Technicians may also be able to 'sniff' for exhaust gasses in the radiator. Also, any sweet, caramel smell can be hot coolant, out the tailpipe or dripping externally.

Your engine may also require the Subaru headgasket sealant. Others here will know the specifics.

Carl

OK. I think it was air in the system that needed purging. Reading stuff, I now better understand the purpose of the 'o'flow bottle' and the need for fluid to be in it so when air in the system expands and exhausts into that bottle, it can draw replacement coolant back into the system.

I've now put 75 miles on it and the temperature gauge gets to the middle range and hasn't moved off of that point except to cool back down after the run. Thanks for the help. I thought I was looking at big $$$ too.

Please investigate whether the Subaru Coolant Conditioner (stop leak) is recommended for your engine.

otherwise, good job!

Carl

Well, yesterday I put 300 miles on the car. The first 100 went just fine, then I made a strong pass where I basically floor it until I pull back in ending at about75 mph. I was just thinking how strong the car was running and about towing the boat to the late. Then I noticed the temp gauge climbing right up into the 'H.'

At the halfway point, I took it to a Subaru dealer to have them check it out. Right off, they asked me how I refilled the system. Seems that the correct way to purge the air is to fill the top block first by removing the top return radiator hose at the radiator and filling that first. They did that, but then reported that they smelled 'gas' in the overflow reservoir. On the printout, they said 'it may still need a head gasket - $1,700 + tax.' And they wouldn't be able to get to it until Monday & Tuesday. So I drove it back home the return 150 miles. But this time, no mash the peddle passing and the temp gauge stayed just where it should. And all that cost $100.

I think I do have a very small head gasket leak that doesn't present it self until the rpm's are run up in a hard pass. Looking back, a hard pass preceded every overheating episode. Driving hard forced gases into the water jacket and then blew all 1/2 the coolant out into the reservoir. Now at

182,000 miles, I have to decide whether $1,700 is a good investment. Hope this helps somebody else. Thanks.

Here in the Seattle area, Kelly Blue Book says your 99 OB is worth $7500 (I got $9,260 the second time I ran it ??) (buy at dealer) if in excellent condition. You may want to run it yourself at

I was lucky when my 2000 OBL blew a gasket, it was still (just barely) inside the special extended warranty on head gaskets. All I had to pay for was the cam belt as I had them replace it while they had it apart.

I'm guessing you like the car, so that gives a little weight towards fixing it.

Trade-in values from KBB without the HG problem. Excellent $4,100 Good $3,625 Fair $2,825

Subtract $1500-2000 from that for the HG..

If it was me with this car, I'd probably fix it. My reasons: $1700 doesn't make a lot of payments on a replacement vehicle. I don't like the later/new Outbacks. I don't like to have to "learn" another vehicle. I'd probably end up eating the $600 sound system upgrades I've put in it. (special case?) There's a lot of miles left in your car, I've seen some with over 300k still running fine.

That's me, but I tend to run my vehicles many years. Overall, even $1700 repair bills are OK if spread over many years and miles.

I'm thinking of fixing it too, for all the reasons you mentioned. I'll still sweat the first thousand miles after a major repair hoping my car didn't catch a 'cold' at the shop as that seems to happen often. Go fix one thing and develop 2 more. ;-)