Oh boy....this is no bueno.

SO whats the worst thing that can happen to a subaru? You guessed it, overheat! My car is having some weird symptoms though. First off I can fire it up and let it idle until it fully warms up and it will stay there. As soon as I go to drive it, however, the proverbial shit hits the fan! It started yesterday, I got the hole in the exhaust fixed temporarily until I can find a cat back and decided to take it for a drive. Ran fine up to the taco bell, idled right where it should be, rove to the local Columbia outlet store to look for a fleece that my dog ate, and on the way home took a backroad with a couple good turns to see what she did. I got through that and noticed the temp gauge pegged. I get home and let it cool down which took only a couple minutes. I thought well hell I have an air bubble. SO I added more coolant and let it run for a bit until the bubbles in the radiator quit coming out, all the while its idling dead in the center of the gauge.

 

I get up this morning and hop in the subaru and sure enough halfway to work here goes the temp. After work drove to the parts store drove around town a bit and as soon as I get out of town there it goes again. We are thinking we may have put the thermostat in backwards, is this possible in a subaru? Sorry for the long winded rant. This was my major fear about buying a subaru. Also when we went to change the thermostat there was half of a thermostat left in it which had been taken out and cut apart then reinstalled. The oil was also changed at the same time as the thermostat and it was not the least bit milky which is a good indicator of a HG leak but isn't always the case with a bad HG. Any ways, what I was trying to say is HELP!!!!

Hey man, was it doing it before you installed the T-stat? I remember you mentioning it was missing when you did the header.

No it wasn't Tony pulled the top hat of the thermostat out and the rest of it was gone.

May not be backwards...but could be defective.

 

Would be my starting location.

Damn,

 

but u can test the thermostat if you really wanted to, just slap it in a pot and boil the water it should open up. you can also rule out the coolant by testing it with a tester

Damn,

 

but u can test the thermostat if you really wanted to, just slap it in a pot and boil the water it should open up. you can also rule out the coolant by testing it with a tester

 

I don't see how the coolant can go bad in 3 days, one jug was brand new and the other i just bought in August.

I have never come across a defective thermostat....not once

 

Neither have I.

Are you sure you got all of the air out of the system when you replaced T stat?

I would do the burp procedure again.

Sometimes Subarus are picky about T stat.

Which one did you replace it with?

OEM, stant, what?

 

O.

if you removed a ''modified'' t-stat, the former owner or mechanic did it for a reason. either the head gaskets are going bad the 'mod' prevented it from overheating or the rad is partially clogged and the 'mod' fixed it. if you want to drive the car and not spend a lot of money and time, put the old t-stat back in. (how long have you had the car, months or years?)

 

look for small bubbles on the over flow bottle when it is '''hot'''. this is the HG indicator. if the coolant is new, a hydrocarbon test may not be accurate. but i agree that if the HG are leaking enough to over heat the engine the hydrocarbons should be there.

 

i think , long term, a bad HG would over heat regardless of the ''modded'' t-stat. so maybe this is just a flow / blockage problem.

What johnegg said ! haha

How was the old thermostat cut apart ? it was most likely cut to let the fluid flow all the time, and with the highest flow, now that you put in an actual one, it still might open up, and when its idling or running at lower rpm's it wont overheat.

Well, now we know why you said that there was no thermostat wasn't in the car when you went to replace it... The PO or someone else took it out because the car was over heating on them.

 

In my testing and trying to figure out my coolant system and all of my over heating, I took the thermostat out just for the heck of it. I didn't over heat once no matter how hard I pushed the car.

 

Our Subaru's cooling systems seemed to be designed so that the engine constantly runs as close to boiling point as possible, to run efficiently and heats up as quick as possible. That is why the thermostat is located after the radiator, and not in between the top of the block and the top of the radiator where it is on a lot of other cars.

 

When our head gaskets fail, the fail at the ring just around the cylinder bore, and when the engine reaches a certain temperature the seal becomes weak and allows the hot compressed gases from the combustion chamber to leak right into the coolant. This super heats the coolant and by the time the thermostat opens up to allow more coolant to run through the engine and then the radiator, it is too late and the engine over heats.

 

Keeping the thermostat open, or partially open with a modification allows as much coolant to run through the system (and most importantly the radiator to cool it) from the start and would allow the even super heated coolant to cool down and not let the engine overheat.

 

I will post a pic soon of where my gasket failed.

if you removed a ''modified'' t-stat, the former owner or mechanic did it for a reason. either the head gaskets are going bad the 'mod' prevented it from overheating or the rad is partially clogged and the 'mod' fixed it. if you want to drive the car and not spend a lot of money and time, put the old t-stat back in. (how long have you had the car, months or years?)

 

look for small bubbles on the over flow bottle when it is '''hot'''. this is the HG indicator. if the coolant is new, a hydrocarbon test may not be accurate. but i agree that if the HG are leaking enough to over heat the engine the hydrocarbons should be there.

 

i think , long term, a bad HG would over heat regardless of the ''modded'' t-stat. so maybe this is just a flow / blockage problem.

 

The former owner changed the thermostat with me Sunday, he had it for a couple months. I've had it a week and a half or so. Kinda makes me sad i traded a perfectly running Jeep! i hope its a clog but the Rad looks new. I'm not blaming it on the guy i got it from, he didn't know. But maybe i should make him give me his STi motor! i got a stant t stat. I'm focusing on the jeep since I have a trail run this weekend but i'll keep up on this thread and thanks guys for all the suggestions, this thing is gonna drive me to drinking. I'll start with the obvious abd see where it gets me but first i gotta get the jeep dirty and clean up a trail!

I may just swap in the old t stat again and run it like that til spring when I can afford to get the HG's done. My buddy charges cheap labor thankfully. Does the engine need to come out?

I wouldn't think that's the best idea, even though it's sort of the only option, to run it that long. It may not last like that. I only had mine out for about an hour and a half of total driving during the entire day.

 

and I found it easiest to take the engine out of the car to do my gaskets. It took me a total of 4 hours to take it out. I removed the radiator, accessories, and the timing assembly before I took it out. And it's easy for two people to lean in and pull it right out, as it doesn't weight too much.

I wouldn't think that's the best idea, even though it's sort of the only option, to run it that long. It may not last like that. I only had mine out for about an hour and a half of total driving during the entire day.

 

and I found it easiest to take the engine out of the car to do my gaskets. It took me a total of 4 hours to take it out. I removed the radiator, accessories, and the timing assembly before I took it out. And it's easy for two people to lean in and pull it right out, as it doesn't weight too much.

 

He bought the car in June and drove it until now like that so I don't think another couple months is gonna hurt it. Plus, I gotta swap the rear axle and T-case on my jeep so i need this thing operational. Also, After some reading i'm sure we didn't get the system bled all the way. Been focusing on making sure my jeep is ready to get flogged on tomorrow. I will go ahead and check out the thermostat, and flush the system. New to boxer engines so its a rookie mistake, not ruling out the dreaded blown HG's though.

Dude I don't mean to bum you out but the HG's are blown for sure. If it's recently happened (which I'm sure you don't know) then you may have a little time but it will only get worse, I had the same thing going on last year and finally replaced the HG's this past June. By the way where did you get the headers from? Any sound clips you can post up or email me? I'm up in Indy but I go to Columbus a lot. I'm looking to get some headers for my OB.

Just make sure that the problem isn't the water pump - a water pump with weak flow may be rectified by the removal of the thermostat.

Well my brother and a deer came into contact at about 80 on the interstate last night, so until he gets a headlight, he is driving the subie with a "custom" thermostat in it(read top half of thermostat). Why in the world would a car with no thermostat have working heat? I'm lost there.

It will, it will just take longer to provide some good, hot heat because it'll take the engine a bit longer to warm up.

 

But, you may not noticed this, and this is because I just realized something very important about the head gaskets failing.

 

Before I did my head gaskets, I would get full on heat in less than a mile of driving. This has been since the gaskets started failing last winter. I noticed that as soon as I replaced my head gaskets, it took a decent amount of time longer to get heat out of the car.

 

In your car, this could be counter acted by the thermostat making that car act like the heat is working properly.

It will, it will just take longer to provide some good, hot heat because it'll take the engine a bit longer to warm up.

 

But, you may not noticed this, and this is because I just realized something very important about the head gaskets failing.

 

Before I did my head gaskets, I would get full on heat in less than a mile of driving. This has been since the gaskets started failing last winter. I noticed that as soon as I replaced my head gaskets, it took a decent amount of time longer to get heat out of the car.

 

In your car, this could be counter acted by the thermostat making that car act like the heat is working properly.

 

I'm still gonna shoot for replacing the gaskets, this is just a temporary fix so we have a spare car to use. should be a week or two before we get all the parts for the civic so it shouldn't be too hard on it.