26 replies to this topic

[AaronCarol]

Can somebody tell me what is wrong with my Legacy wagon? First off, there is no heat coming out of the vents. Secondly, the engine overheats to almost boiling over. I've checked the coolant level and tried burping (but not sure if I was successful).
I also checked the coolant and reservoir tank to see if there was any visible oil in the coolant but there doesn't appear to be any. I noticed the cooling system did pressurize after running the engine but the radiator cap never got hot. Even though the gauge said the engine was very hot, when I removed the "cold" radiator cap I was surprised to find the coolant bubbling out of the radiator was also cold.

Can somebody explain this to me?

[grossgary]

replace your thermostat. if it's stuck closed you can experience exactly what you have here.

do not drive the car while it's running this hot. not good for engine, seals or gaskets.

[coloradosubarules]

Sounds like a typical case of air lock (bubbles in the cooling system) and there is an easy way to fix this.

Pop the hood
take the rad cap and bleeder screw off (top of radiator on the left)
Start car and fill rad
let idle untill thermostat opens and add water
fill untill water overflows rad

Some people do this once and think they are done..just do it untill your rad won't hold a single more drop.

Weither or not you want to have the heater on during this process is up to you.

#700!!!

[AaronCarol]

replace your thermostat. if it's stuck closed you can experience exactly what you have here.

do not drive the car while it's running this hot. not good for engine, seals or gaskets.

Just humor me here but if it was just a thermostat shouldn't I still have heat to the cabin. If indeed it is stuck closed and not allowing water to the radiator it should still be circulating in the other loop and also the cabin heater block shouldn't it? Or are Subarus different.

[AaronCarol]

Thanks for the tip. But I tried burping it again as per your instructions, engine running, rad cap and bleeder screw off, and I even drove the front wheels onto ramps to get the front end in the air. Then I topped up the fluid. I noticed that the fluid seemed to be expanding. Once the car warmed up coolant started to spurt up 4" out of the bleeder hole in a rhythmic action. I revved the engine and more coolant came spurting out. So what do you think is happening? Anyone?

Sounds like a typical case of air lock (bubbles in the cooling system) and there is an easy way to fix this.

Pop the hood
take the rad cap and bleeder screw off (top of radiator on the left)
Start car and fill rad
let idle untill thermostat opens and add water
fill untill water overflows rad

Some people do this once and think they are done..just do it untill your rad won't hold a single more drop.

Weither or not you want to have the heater on during this process is up to you.

#700!!!

[AaronCarol]

Thanks for the tip. But I tried burping it again as per your instructions, engine running, rad cap and bleeder screw off, and I even drove the front wheels onto ramps to get the front end in the air. Then I topped up the fluid. I noticed that the fluid seemed to be expanding. Once the car warmed up coolant started to spurt up 4" out of the bleeder hole in a rhythmic action. I revved the engine and more coolant came spurting out. So what do you think is happening? Anyone?

Think I figured it out. Did an exhaust in the coolant check and it turned out possitve. Guess I have a blown head gasket

[cookie]

Not what you wanted to hear I'm sure.

[coloradosubarules]

Do you notice smoke from the exhaust? Usually when antifreeze burns it stinks and you can really see it.

Did you add water to a hot engine? Ever think the water pump is pushing it faster than your radiator can handle, therefore blowing out the top?

Try filling the rad till it overflows, put the radiator cap on and then take it for a drive. Does it smoke? Overheat? Got heat?

Get back to us.

[AaronCarol]

To answer your questions: no i don't notice smoke coming out from the exhaust but there is a funny smell of burnt coolant in the air but I can't quite tell where it's coming from, it can even be noticed in the cab. Seeing as Sube's pull the coolant from the radiator via the top hose (I'm told) it is strange to me that the coolant that I observed spurting out was spurting out the bleed screw hole and not the rad cap hole, as you know the bleed screw hole is right where the top rad hose joins the rad. After a few minutes it did start coming out the rad cap hole but not to the same extent. It seemed the coolant was expanding but not circulating. In my chev 350 I can open the rad cap and see the circulation, it seems odd to me that it stays completely still in the rad in the subaru. Just to double check, now that the car is cooled down I am going to fill the rad one more time till it overflows and take it for a drive keeping in mind to look for smoke from the exhaust and I'll try to pinpoint the smell.

Do you notice smoke from the exhaust? Usually when antifreeze burns it stinks and you can really see it.

Did you add water to a hot engine? Ever think the water pump is pushing it faster than your radiator can handle, therefore blowing out the top?

Try filling the rad till it overflows, put the radiator cap on and then take it for a drive. Does it smoke? Overheat? Got heat?

Get back to us.

[AaronCarol]

Ok, went for one more round same result. Filled rad, from both ends, and filled reservoir. car overheated as usual. top rad hose was boiling inside, bottom rad hose cold, rad cap cold, coolant in rad barely hot. Couldn't notice any smoke coming out the exhaust pipe, and didn't notice any smell. And still no heat in the cabin the entire time.

[Gnuman]

Once the car warmed up coolant started to spurt up 4" out of the bleeder hole in a rhythmic action. I revved the engine and more coolant came spurting out. So what do you think is happening? Anyone?

To answer your questions: no i don't notice smoke coming out from the exhaust but there is a funny smell of burnt coolant in the air but I can't quite tell where it's coming from, it can even be noticed in the cab. Seeing as Sube's pull the coolant from the radiator via the top hose (I'm told) it is strange to me that the coolant that I observed spurting out was spurting out the bleed screw hole and not the rad cap hole, as you know the bleed screw hole is right where the top rad hose joins the rad. After a few minutes it did start coming out the rad cap hole but not to the same extent. It seemed the coolant was expanding but not circulating. In my chev 350 I can open the rad cap and see the circulation, it seems odd to me that it stays completely still in the rad in the subaru. Just to double check, now that the car is cooled down I am going to fill the rad one more time till it overflows and take it for a drive keeping in mind to look for smoke from the exhaust and I'll try to pinpoint the smell.

I would look to your first quote for the source of the smell. . . .

This sounds to me like the thermostat is stuck closed, which would prevent burping as well, so air pockets could also be present. . . (and they would expand, pushing the coolant up and out of the rad when the cap was off). I would change the thermostat (with a genuine Subaru one) and burp the system again before declaring the gaskets to be gone. . .

[anoblenate]

I would look to your first quote for the source of the smell. . . .

This sounds to me like the thermostat is stuck closed, which would prevent burping as well, so air pockets could also be present. . . (and they would expand, pushing the coolant up and out of the rad when the cap was off). I would change the thermostat (with a genuine Subaru one) and burp the system again before declaring the gaskets to be gone. . .

is there any way to test a t-stat? like put it in boiling water or something like that? i had the same problem, but my headgaskets blew for sure and now i'm putting an ej22 into my legacy gt. i don't want to put in the old t-stat if it may be bad and comprimise my precious new engine ; )

[cookie]

with a thermometer. Note the temp when it opens. Keep in mind its a wear item that opens and closes constantly. It will die of metal fatige after its designed interval. Since it can kill your engine and is cheap is this a good place to save money?

[cookie]

thermostat kill a head gasket. We will know after he tests I am sure.

[frag]

thermostat kill a head gasket. We will know after he tests I am sure.

Are'nt thermostats designed to stay open when they fail?

[AaronCarol]

Are'nt thermostats designed to stay open when they fail?

Only "failsafe thermostats" are designed to stay open when they fail. When looking for a replacement from an auto parts store I couldn't find one for a subaru. It looks like all engines that subaru makes though take the same picking thermostat! At least the page of engines that I looked at. Maybe a guy could find a thermostat with the same dimensions and temp range for another make that is a failsafe and use it instead. There is a thread in here I noticed of a guy that successfully used a chevy 350 t-stat in his sube.

[frag]

Only "failsafe thermostats" are designed to stay open when they fail. When looking for a replacement from an auto parts store I couldn't find one for a subaru. It looks like all engines that subaru makes though take the same picking thermostat! At least the page of engines that I looked at. Maybe a guy could find a thermostat with the same dimensions and temp range for another make that is a failsafe and use it instead. There is a thread in here I noticed of a guy that successfully used a chevy 350 t-stat in his sube.

Hi,
What I meant is I think I remember that the last time I checked the functionning of the OEM thermostat I was installing the stat was closing while compressing the spring. So I infered that if the expanding mecanism that closes the stat failed the spring would keep it open. Wrong?

[cookie]

engines. I too like the idea of the new ones that fail open, and perhaps the next time my Subie needs one I will look at them. None I have seen yet had a bleed hole which Subies need.

[Cougar]

Along with the new headgaskets I would replace the thermostat. It has to be stuck closed as Grossgary suggested for the radiator not to be warm. This also may be what caused the headgaskets to fail but that is hard to say for sure. You may want to replace the radiator also at this time if it is not real clean.

[kudd]

I had this exact same problem w/my '90 2.2L. ( I don't know what motor number...can't figure out where you find that.) I replaced t-stat, (old one seemed to work properly,) hot top hose, cold cap and bottom hose...same deal.

When it first happened I drove it home, by starting, going as fast as I could before it started to overheat, then shutting down and coasting. Did this a few times, sitting beside the road between bursts while it cooled. The last time...all of the sudden heat from vents, guage went down to normal, so I just drove home with t-stat failure implanted in my brain.

This happened again after I put the new t-stat in, which I checked and it too worked. So I drove for awhile with no t-stat, little->no heat but I guess that keeps the bubbles from blocking off the circulation.

Anyhow, it ended up being head gaskets, (replaced, all's well now). And I also couldn't see steam in the exhaust, or even smell the sickly-sweet anti-freeze smell, or any sign of it leaking outside...but it was going somewhere for sure!

Good luck and cheers!
Kudd

[Nug]

Impeller detached from water pump?

Hey, it happens.

[Cougar]

After reading the original post again I now think that there is a headgasket problem as was pointed out by another poster.

[steved]

I'm having similar problems - '97 outback -118k - with the 2.5L engine; overheats after being on road for 15-20 mins. Thermostat has been replaced, mechanic "burped" the cooling system today - still overheats.

Is hydrocarbon test next step to verify that it has joined the infamous ranks of subarus with headgasket problems?

The water pump and radiator check out ok; I did test the old t-stat and it was functioning properly.

The new t-stat I put in doesn't have the little bleeder valve. Is this critical? SHould I stick the old (genuine Subaru) back in?

Also - can someone give me a quick overview of how to properly bleed air out of the cooling system?

Steve

[coloradosubarules]

T-stats are pretty cheap. Don't test one and then re-install it just to save a buck. It is just cheap insurance to put a new Subaru t-stat in.

Process of elimination.....

[Gnuman]

I'm having similar problems - '97 outback -118k - with the 2.5L engine; overheats after being on road for 15-20 mins. Thermostat has been replaced, mechanic "burped" the cooling system today - still overheats.

Is hydrocarbon test next step to verify that it has joined the infamous ranks of subarus with headgasket problems?

The water pump and radiator check out ok; I did test the old t-stat and it was functioning properly.

The new t-stat I put in doesn't have the little bleeder valve. Is this critical? SHould I stick the old (genuine Subaru) back in?

Also - can someone give me a quick overview of how to properly bleed air out of the cooling system?

Steve

There is a reason for that hole, and yes, you need it. Better to just get a new Subaru T-stat with the hole, so burping will actually work. . . .

The method for burping the cooling system has been posted several times here, do a forum search for "burp the cooling system" and you should find it easily.