Thermostat Failiure?

[oamster]

What's up guys? I just bought a '97 Legacy GT with 145k miles on it. I live in northern Arizona where it tends to snow a lot during the winter. It snowed today, so I decided to go have some fun in my new AWD. Went out to a local abandoned parking lot where there was snow (1"-2") and had some fun drifting and doing donuts. Everything was fine, I left the parking lot and went to a local store where I noticed my thermostat was almost to the H. So I immediately turned off the engine, and popped the hood. There was NO smoke, or steam. So I opened the radiator cap and coolant sprayed out. Waited till it stopped and put it back on. I went back into the car and turned it back on and the temp was at normal running temperature, THEN went back up to the H and then back down. It keeps going from normal, to the H (straight up). No smoke, no steam, nothing. So I thought that maybe it needed more coolant, so I filled up the res with bottled water.

As of right now, it still goes up to H (even when driving) and drops back to normal temp. And repeats.


I checked the oil and didn't see any signs of coolant or water...

Any ideas?

[mike-tracy]

After turning the motor off and letting it cool all the way, is there any change in the amount of coolant in the overflow bottle?

[oamster]

Not that I can see. I'll go check it right now since it's been off for almost an hour.

[oamster]

Also, before this happened. The temp would sit in the middle and the vents would be blowing cold air. I noticed ONCE that the needle jumped a little bit and THEN the vents started blowing hot air.

[mike-tracy]

That's a good sign of having a trapped air bubble or clogged heater core.

[oamster]

Okay, just went down and checked it. It was completely empty. When I filled it before, I overfilled it. So now I filled it up to the "full" line and having it idle. Anything I should be worried about?

[mike-tracy]

Just see what happens after driving it a bit and letting it cool down all the way. If it's empty every time the motor cools down (after refilling it each time), then it's possible the motor is consuming coolant. But if it only happens a couple of cycles, then it's just getting a LOT of air out of the system. I would put an OEM thermostat in before you jump to conclusions because aftermarket ones are known to cause issues in Subarus.

[oamster]

Would that be a sign of a blown head gasket? I had it idling for about 5 minutes and the temp is normal. I noticed bubbles coming up into the overflow bottle when I shutoff the engine. I'll go down and check in a few minutes to see if the bottle is empty. What should I do if the engine is consuming coolant?

[mike-tracy]

Like I mentioned, replace the thermostat first with an OEM one, and bleed the system properly.

[oamster]

Like I mentioned, replace the thermostat first with an OEM one, and bleed the system properly.
I'll try that. I'm going to try and test my OEM thermostat and see if it's bad using the boiling water method. About how much coolant would it take to fill the system?

[mike-tracy]

Here's a helpful PDF from the service manual. You should have around 6.4 qts of coolant when completely full.
PDF:
http://www.subaruoutback.org/forums/att ... stid=69004 (http://www.subaruoutback.org/forums/attachment.php?s=&postid=69004)

[oamster]

Here's a little update on my situation.
I removed the thermostat and but the hose back on the housing. The car ran great, NO signs of overheating (it was WAYYYY cold, like RIGHT above the notch where the C is). So I decided to buy a thermostat (not OEM, I know I know.) and install it. Installed it, the right way (or so I think) with the spring facing towards the block, and the little bead thing facing out. I then filled the car with coolant, bled as much of the air out of it as I could, and took it a spin around the block. What do ya' know, it started to overheat.

I'm starting to believe that I could have a blown/leaking head gasket. I checked the oil, and there's NO milky residue, the oil is dark, and looks normal. As for the overfill tank, it has a bubble coming up every 3-5 or so seconds. When I open the throttle, the bubbles stop. But shortly after, they reappear. There's no smoke coming from the exhaust, and no smell of coolant that I can sense.


Should I still try replacing the thermostat with an OEM one? Or do I have bigger problems.

[ouch1011]

i think you still have air in the system. Head gasket failure would cause overheating regardless of whether you had a tstat in there or not, because the head gasket failure causes overheating by either pushing combustion gases into the cooling system (pushing the coolant out) or by allowing coolant into the combustion chamber and consuming it, both causing coolant circulation to stop.

[oamster]

What would be a fool-proof way to make sure that there's no air trapped in the system? I'm about tempted to keep running the car without the tstat since it's starting to get hotter.

[mike-tracy]

I can't recommend getting an OEM thermostat enough - the problems with running other ones are well documented on every subaru forum I've seen. The OEM thermostat has a bleeder that lets trapped air out (from the bottom of the radiator) that most non-oem ones don't have.

Here's a couple things to get most of the air out:

Park the car on ramps or on a steep hill, nose up.
Open the radiator cap AND bleeder screw.
Fill up till it can't take any more, and fill up the overflow bottle to the full line.
Put the radiator cap back on.
Using a funnel, fill more coolant into the bleeder screw hole, put the bleeder screw back on,
and let the car warm up to operating temperature with the heater on full blast (helps draw coolant into heater core)
Turn it off, and wait for it to cool all the way, and top off the radiator again the usual way, but with the bleeder screw open to let out any last air. Let it warm up and cool down again an additional time and refill again.

This technique works for me, and is a couple extra steps from the endrench procedure but I haven't had any problems since.

[subikid90]

I can't recommend getting an OEM thermostat enough - the problems with running other ones are well documented on every subaru forum I've seen. The OEM thermostat has a bleeder that lets trapped air out (from the bottom of the radiator) that most non-oem ones don't have.

Here's a couple things to get most of the air out:

Park the car on ramps or on a steep hill, nose up.
Open the radiator cap AND bleeder screw.
Fill up till it can't take any more, and fill up the overflow bottle to the full line.
Put the radiator cap back on.
Using a funnel, fill more coolant into the bleeder screw hole, put the bleeder screw back on,
and let the car warm up to operating temperature with the heater on full blast (helps draw coolant into heater core)
Turn it off, and wait for it to cool all the way, and top off the radiator again the usual way, but with the bleeder screw open to let out any last air. Let it warm up and cool down again an additional time and refill again.

This technique works for me, and is a couple extra steps from the endrench procedure but I haven't had any problems since.

I had the same issue and mike is totally right. Buy the OEM thermostats ONLY! The method he described works perfectly with our cars.

[oamster]

Another update. I decided to take out the thermostat entirely, and the engine is running cool. No overheating, goes up to normal temp while idling and drops when driving. I made sure to bleed the system of air as much as I possibly could; but there are bubbles still coming up into the overflow bottle. Also, I asked my friend to rev the motor up a bit so I could check out the exhaust, I have a leak, it whistles, and there's a puff of white smoke (vapor) upon rev'ing the engine. But when idling there's none. There's no oil in the overflow bottle, and no coolant/water in the oil.

I'm starting to think that I have a leaking head gasket. So I was thinking about purchasing some Steel-Sealer and using that as a temporary fix until I can save up some cash for a ej20t swap. I really don't want to throw $1500 or so dollars towards getting the HG replaced and then later on down the road getting a new engine for a swap.

[ouch1011]

What I have seen from pretty much every head gasket failure on the phase 1 engines is that it overpressurizes the cooling system, which causes the cap to start venting coolant/pressure out in to the reservoir. So common sign is low coolant in the radiator, overfull in the reservoir. When mine failed, it pushed so much coolant out of the cooling system that it filled the reservoir completely to the top and started dumping it on the ground.

So, I'm still not convinced you have a head gasket problem. If you really are certain that you have a head gasket issue and you want to verify, take it to a mechanic and ask them to do a chemical block test. This is basically a chemical that changes color (most I've seen go from blue to yellow) in the presence of hydrocarbons (combustion gases). What they do is pour the chemical into a container with a one way valve on it, then suck a vapor sample from your cooling system through the chemical and see what happens. If it changes color, you have hydrocarbons in your cooling system, which probably indicates blown head gasket.

But as much as I don't recommend driving without a t-stat, especially when it is cold, if the car doesn't overheat with it removed, then just leave it that way. Worst that'll happen is that you increase your engine wear a bit. Don't run any sealant crap in the cooling system unless you want to replace every last bit of the cooling system (radiator, heater core, all the hoses) because it will plug it up.

[oamster]

What I have seen from pretty much every head gasket failure on the phase 1 engines is that it overpressurizes the cooling system, which causes the cap to start venting coolant/pressure out in to the reservoir. So common sign is low coolant in the radiator, overfull in the reservoir. When mine failed, it pushed so much coolant out of the cooling system that it filled the reservoir completely to the top and started dumping it on the ground.

So, I'm still not convinced you have a head gasket problem. If you really are certain that you have a head gasket issue and you want to verify, take it to a mechanic and ask them to do a chemical block test. This is basically a chemical that changes color (most I've seen go from blue to yellow) in the presence of hydrocarbons (combustion gases). What they do is pour the chemical into a container with a one way valve on it, then suck a vapor sample from your cooling system through the chemical and see what happens. If it changes color, you have hydrocarbons in your cooling system, which probably indicates blown head gasket.

But as much as I don't recommend driving without a t-stat, especially when it is cold, if the car doesn't overheat with it removed, then just leave it that way. Worst that'll happen is that you increase your engine wear a bit. Don't run any sealant crap in the cooling system unless you want to replace every last bit of the cooling system (radiator, heater core, all the hoses) because it will plug it up.
Sounds a lot like what's going on with mine... I've been noticing that there's a little bit of coolant on/around the cap of the reservoir and the reservoir is almost to the top. Sometime this week I'll go and get it tested. Do you think Autozone or another place would test it for free? If not, then that's fine. Shouldn't be too expensive.

[oamster]

Can anyone recommend a head gasket set? I don't know if I should go OEM on the soul purpose of the OEM gaskets going bad. I was looking at one of these, but I don't know what ones to get exactly.

http://rallispec.com/prod_valve.htm
(scroll to bottom of the page)

[B's Legacy Wagon]

To me its a toss up i would think OEM would be good but at same tiem i am always looking for things to upgrade to better versions. not sure if this is one of them it looks like it might be good. but i would see if any more mebers have better information on this. i am definatly following this thread so if i have any problems like this in the future.

[ouch1011]

The OE gaskets that typically fail are not the same as the OE gaskets you would get from the dealer today, they are an updated design. Or at least mine were. I went OE because I knew they would be good quality and I can get them cheaper than most any other set I could find.

From what I can see a big part of the high HG failure rate on these engines is not the gasket design specifically but the design of the head and block. There is very, very little sealing area between the combustion chamber and the coolant passages at some points.

[ouch1011]

What I have seen from pretty much every head gasket failure on the phase 1 engines is that it overpressurizes the cooling system, which causes the cap to start venting coolant/pressure out in to the reservoir. So common sign is low coolant in the radiator, overfull in the reservoir. When mine failed, it pushed so much coolant out of the cooling system that it filled the reservoir completely to the top and started dumping it on the ground.

So, I'm still not convinced you have a head gasket problem. If you really are certain that you have a head gasket issue and you want to verify, take it to a mechanic and ask them to do a chemical block test. This is basically a chemical that changes color (most I've seen go from blue to yellow) in the presence of hydrocarbons (combustion gases). What they do is pour the chemical into a container with a one way valve on it, then suck a vapor sample from your cooling system through the chemical and see what happens. If it changes color, you have hydrocarbons in your cooling system, which probably indicates blown head gasket.

But as much as I don't recommend driving without a t-stat, especially when it is cold, if the car doesn't overheat with it removed, then just leave it that way. Worst that'll happen is that you increase your engine wear a bit. Don't run any sealant crap in the cooling system unless you want to replace every last bit of the cooling system (radiator, heater core, all the hoses) because it will plug it up.
Sounds a lot like what's going on with mine... I've been noticing that there's a little bit of coolant on/around the cap of the reservoir and the reservoir is almost to the top. Sometime this week I'll go and get it tested. Do you think Autozone or another place would test it for free? If not, then that's fine. Shouldn't be too expensive.

Autozone won't do something like that, you'll probably need to take it to an actual auto repair shop, i.e. not a Pep Boys or a Meineke or something like that. My shop charges about $40 to do it because it can take quite a while to get a definitive result.

[oamster]

I would think that a high performance HG would last a LOT longer than the OEM counterpart. Right? Also, what are the chances of my heads being warped due to the HG being blown?

And on that rallispec site, they have 3 different versions. What HG would I use?
RCH-4264 Head Gasket Set EJ25 (1.1mm) $190
RCH-4264B Head Gasket Set EJ25 (0.78mm) $190
RCH-2145 Head Gasket Set EJ25 (1.5mm) $210

[oamster]

UPDATE.

I was 99% sure that it was a HG problem. So friday morning I went out and bought two HGs from napa for $50 a piece. They are multi layered steel. So far, I got the passenger side head almost done, except putting the cams and shit back in. It turns out, the passenger side HG failed just like all the other people's HGs did. Cylinders 1 and 3. The black stuff was 'washed' away to allow combustion gases into the cooling ports. I don't believe cylinders 2 and 4 have any HG issues, but I might as well replace the head on that side while I'm at it.

All I have to say is torquing the head bolts AND rotating them to spec, and removing the cam gears was the hardest part(s) of doing this. But I have a feeling the timing will be a pain... I'll keep this updated.

[oamster]

So I finished the car today. Put everything back together, and she started right up. No overheating problems. No bubbles in the overflow bottle. Good to go. BUT, I believe that there's a slight knock. IMO it doesn't sound really bad, and it's not loud. But audible from inside the cab. I don't know if I should just keep it as-is or if I should tear her apart once more.
I also used valvoline 5w30 full synthetic.