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Old 10-10-2009, 09:08 PM   #1
thenexlevel
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Default 98 Legacy Outback - Temp Sensor Overheats and No More Cabin Heat???

Hey guys,

Just picked up a 98 legacy outback yesterday for the winter dd and it was driving fine until today I noticed that the coolant temp sensor all of a sudden shoots up to H and stays there. I pulled the car over and popped the hood and didn't see any smoke or leaking anywhere...so I'm guessing this is a sensor issue? But whats weird is cabin heat no longer works wither...turned it up all the way with heat and its just blowing cold air.

Are these two things related somehow or totally different? Any suggestions for me?
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Old 10-10-2009, 10:30 PM   #2
Mulder
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If you're lucky it's a stuck thermostat, if you're not it's a head gasket. Either way don't drive it any more until it's diagnosed and fixed.
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Old 10-11-2009, 01:00 AM   #3
Degenerate
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Get it diagnosed...
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Old 10-11-2009, 11:18 AM   #4
Charlie-III
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Quote:
Originally Posted by Mulder View Post
If you're lucky it's a stuck thermostat, if you're not it's a head gasket. Either way don't drive it any more until it's diagnosed and fixed.
+ a bazillion.

I would almost bet you have 1 or 2 bad head gaskets (AKA, "HG's").

I have been through 2 sets in my 98 Legacy GT and one set in my wifes 99 Impreza L (I know, I know, "The 2.2L's NEVER blow HG's").

I would first research "burping the coolant system" and see if that fixes your issue.
If that won't help, you can try and replace the thermostat in the water pump.
But in the end, I feel you will need to either do HG's or a junkyard engine (or rebuilt if you have the money).
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Old 10-11-2009, 07:50 PM   #5
thenexlevel
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I spent a good amount of time with this, drained oil and did not see coolant, looked in the overfill bottle and coolant was gone....strange. I flushed out the radiator and drained what came out from the theromostat and replaced it...made sure to burp the system and same thing.

The car will heat up to a certain point while idling and it won't move until I start driving the car...then it heats up really fast and overheats. While its idleing and the temp is 1/2 way on the gauge there is no heat...

Something interesting I found out, after the car heated up, I squeeze the upper radiator hose and its hot and expanded but when I sequeeze the lower radiator house, its not hot and hardly full at all. This makes me think there isn't coolant being circulated into the engine and it sounds like its the water pump. If the water pump failed, would this be the situation?

I'm debating if i should try to replace the water pump/timing belt tonight.
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Old 10-11-2009, 10:21 PM   #6
Charlie-III
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I have yet to see a Subaru water pump fail.
Normally, when ANY vehicular water pump fails, it leaks through the shaft seals and drops coolant on the ground, it does NOT stop circulating coolant.

I still say, sorry, that you have a failed HG.
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Old 10-11-2009, 11:35 PM   #7
thenexlevel
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Quote:
Originally Posted by Charlie-III View Post
I have yet to see a Subaru water pump fail.
Normally, when ANY vehicular water pump fails, it leaks through the shaft seals and drops coolant on the ground, it does NOT stop circulating coolant.

I still say, sorry, that you have a failed HG.

I come from other cars where if there is a blown head gasket, you will see coolant mix with oil. You'll see it either in the oil pan or in the coolant overfill, the coolant has to go somewhere if the head gasket is going bad.

So can someone explain to me how a blown head gasket can casue my overheating problem if the coolant isn't flowing somewhere its not? Where else can the coolant be flowing then?
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Old 10-12-2009, 12:00 AM   #8
69subaru360
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Exhaust gas pushes into the coolant. It's extremely common. Most of the 96-99 Outbacks blow the head gaskets eventually. Only use the latest part number gaskets from a Subaru dealer to fix it or you will be doing it again.
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Old 10-12-2009, 12:15 AM   #9
thenexlevel
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Originally Posted by 69subaru360 View Post
Exhaust gas pushes into the coolant. It's extremely common. Most of the 96-99 Outbacks blow the head gaskets eventually. Only use the latest part number gaskets from a Subaru dealer to fix it or you will be doing it again.
So what happens exactly? The coolant doesnt' leak but exahust gas gets into the coolant? So it creates air pockets or does it overheat the coolant?
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Old 10-12-2009, 12:42 AM   #10
69subaru360
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Quote:
Originally Posted by thenexlevel View Post
So what happens exactly? The coolant doesnt' leak but exahust gas gets into the coolant? So it creates air pockets or does it overheat the coolant?
It heats up the coolant, pushes it out the overflow and makes air pockets. So yes to all of the above.
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Old 10-12-2009, 03:32 AM   #11
iluvdrt
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Quote:
Originally Posted by thenexlevel View Post
I spent a good amount of time with this, drained oil and did not see coolant, looked in the overfill bottle and coolant was gone....strange. I flushed out the radiator and drained what came out from the theromostat and replaced it...made sure to burp the system and same thing.

The car will heat up to a certain point while idling and it won't move until I start driving the car...then it heats up really fast and overheats. While its idleing and the temp is 1/2 way on the gauge there is no heat...

Something interesting I found out, after the car heated up, I squeeze the upper radiator hose and its hot and expanded but when I sequeeze the lower radiator house, its not hot and hardly full at all. This makes me think there isn't coolant being circulated into the engine and it sounds like its the water pump. If the water pump failed, would this be the situation?

I'm debating if i should try to replace the water pump/timing belt tonight.

If it is a 2.5, you have a blown HG. Mine did this on every occasion the HG was blown. I bet after driving it for a few miles (10) the over flow bottle is full too.
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Old 10-12-2009, 04:22 AM   #12
Charlie-III
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Quote:
Originally Posted by iluvdrt View Post
If it is a 2.5, you have a blown HG. Mine did this on every occasion the HG was blown. I bet after driving it for a few miles (10) the over flow bottle is full too.
Yep, all mine did it as well as my wifes (like I listed before).
None of them had oil in the coolant or coolant in the oil.
All of them would push coolant into the overflow, it would overfill and dump on the ground (when hot) and then the radiator would show up low later when cool.
I would have temp spikes, a cold heater, loss of coolant, etc.
This is VERY common on the phase-1 2.5L NA engines.
The later (~1999+) phase-2 engines also had HG issues, but those just leaked coolant on the ground.
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