2000 Legacy head gasket problems

Rally STi Guy · 11-26-2012, 10:30 AM

My family owns a 2000 Legacy L sedan that has been having problems. It was having problems with overheating. My sister would drive it and would over heat it to the extent that it would turn off. I thought for sure that it was a blown head gasket. So when I was home for the summer I dug into the car. My father had put some “Blue Devil” head gasket repair into the cooling system before I had gotten to it. So the I first drained all the coolant that was in the system and ran Prestones super flush through the system to remove all of that and clean up the system. After having pulled off the head, I went about investigating the head gaskets. There were no clean signs that the head gaskets had failed, we were hoping that there would be a clear sign that one had failed. The was a small spot that we had decided was where it had failed. After that, we cleaned up the mating surfaces on the heads and the block and checked to make sure they were flat using a straight edge. We probable spent about an hour checking all four surfaces. We had determined that they did not need to be resurfaced at a machine shop. (We also checked the cylinders to see if they had been damaged from overheating, they had not been) So I bolted the heads back on with Felpro head gaskets that we had gotten in the head set for Auto Zone along with new head bolts that we had also picked up. We followed the freaking long tightening sequence that is needed to bolt them back on. We also replaced the water pump while we were in there just to be safe. The timing belt had been replaced about 20,000 miles earlier so we left it alone. After getting it all back together we replaced the oil and out straight distilled water in the system. I made sure that I had gotten all the air out of the system. I then tested the system. This is the problem that I am getting.
I’ll accelerate the car hard as if one is getting on the highway and the car will get hot. If I then drive the car with little throttle input, the temperature will come back down. When I then look under the hood the over flow tank is now full and the up radiator hose feels like there is air in it. If I then let it sit, it will pull all the water from the res back into the system. After it is completely cooled, off I will pull off the radiator cap and there isn’t any room for more water to go in. It has me really confused on why it is doing that. Has anyone else had any kind of problems like this?

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Charlie-III · 11-28-2012, 08:55 AM

First off, what radiator cap & thermostat? I've had issues with some that are not Subaru OEM.

DohcEj22e · 11-28-2012, 07:43 PM

Did you purge air from the system as you filled it up w/coolant?
This is very important as trapped air can cause temperature spikes.

Rally STi Guy · 11-30-2012, 09:21 AM

I did purge the air from the system when I filled it with distilled water. The cap is OEM but the Thermostat is not. I thought it might be the thermostat that was giving me issues as well, so I have tested it. (in a pot of water on the stove while watching the temp) but it checked out after several tests.

Patrick Olsen · 11-30-2012, 01:42 PM

The problem as you're describing it sounds like an internal head gasket leak, causing the cooling system to be pressurized by combustion chamber pressure.

Not that it should matter for this problem, but did you put anything in other than distilled water? Even if the car never sees cold temperatures, it's a good idea to have at least some coolant or coolant conditioner in there to minimize corrosion and keep the system healthy.

And for the SOHC engines it's a good idea to use the Subaru-specific coolant conditioner (which may be designed to be use with Subaru coolant, I'm not real sure on that as I don't have one of those engines).

Rally STi Guy · 11-30-2012, 10:29 PM

I would agree with you that it sounds like the gasket is leaking but if that were the case I would think that I would have to add coolant/water to the system because it had gotten blown out and replaced with combustion gases. Am I not thinking about that right? When the engine cools off there isn't any room in the system to add more coolant/water.
I had put in straight water just to test the system. I didn't want to have put coolant in only to have to take it apart again and have it go all over the place. My father has put coolant in the system currently until I work on it again when I'm home for Christmas.
The felpro head gasket was three sheets of metal. Has anyone used them before or a similar style and have had any problems.
My current plan for redoing the head gasket it have both heads decked by a machine shop, new head bolts and buy OEM head gaskets.

Patrick Olsen · 12-01-2012, 04:25 PM

Understand about using just water for the sake of testing.

I checked Fel-Pro's website before I posted initially and their gaskets are MLS (multi-layer steel), which is the same thing as OEM, so there really shouldn't be an issue there.

When I've had internal head gasket leaks on my car, the only time I would actually lose coolant was if I pushed the car hard enough / long enough that it would overflow the overflow bottle and blow coolant all over the driver side of the engine bay.

11-26-2012, 10:30 AM	#1
Rally STi Guy Scooby Newbie Member#: 210109 Join Date: Apr 2009 Chapter/Region: TXIC Location: Wise County Vehicle: 2004 STi PSM	2000 Legacy head gasket problems My family owns a 2000 Legacy L sedan that has been having problems. It was having problems with overheating. My sister would drive it and would over heat it to the extent that it would turn off. I thought for sure that it was a blown head gasket. So when I was home for the summer I dug into the car. My father had put some “Blue Devil” head gasket repair into the cooling system before I had gotten to it. So the I first drained all the coolant that was in the system and ran Prestones super flush through the system to remove all of that and clean up the system. After having pulled off the head, I went about investigating the head gaskets. There were no clean signs that the head gaskets had failed, we were hoping that there would be a clear sign that one had failed. The was a small spot that we had decided was where it had failed. After that, we cleaned up the mating surfaces on the heads and the block and checked to make sure they were flat using a straight edge. We probable spent about an hour checking all four surfaces. We had determined that they did not need to be resurfaced at a machine shop. (We also checked the cylinders to see if they had been damaged from overheating, they had not been) So I bolted the heads back on with Felpro head gaskets that we had gotten in the head set for Auto Zone along with new head bolts that we had also picked up. We followed the freaking long tightening sequence that is needed to bolt them back on. We also replaced the water pump while we were in there just to be safe. The timing belt had been replaced about 20,000 miles earlier so we left it alone. After getting it all back together we replaced the oil and out straight distilled water in the system. I made sure that I had gotten all the air out of the system. I then tested the system. This is the problem that I am getting. I’ll accelerate the car hard as if one is getting on the highway and the car will get hot. If I then drive the car with little throttle input, the temperature will come back down. When I then look under the hood the over flow tank is now full and the up radiator hose feels like there is air in it. If I then let it sit, it will pull all the water from the res back into the system. After it is completely cooled, off I will pull off the radiator cap and there isn’t any room for more water to go in. It has me really confused on why it is doing that. Has anyone else had any kind of problems like this? * Registered users of the site do not see these ads.

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11-28-2012, 08:55 AM	#2
Charlie-III Scooby Specialist Member#: 30669 Join Date: Dec 2002 Chapter/Region: Tri-State Location: 07456, North NJ Vehicle: 1998 Legacy 2.5GT Silver Sleeper Wagon	First off, what radiator cap & thermostat? I've had issues with some that are not Subaru OEM.

11-28-2012, 07:43 PM	#3
DohcEj22e Scooby Newbie Member#: 289011 Join Date: Jul 2011	Did you purge air from the system as you filled it up w/coolant? This is very important as trapped air can cause temperature spikes.

11-30-2012, 09:21 AM	#4
Rally STi Guy Scooby Newbie Member#: 210109 Join Date: Apr 2009 Chapter/Region: TXIC Location: Wise County Vehicle: 2004 STi PSM	I did purge the air from the system when I filled it with distilled water. The cap is OEM but the Thermostat is not. I thought it might be the thermostat that was giving me issues as well, so I have tested it. (in a pot of water on the stove while watching the temp) but it checked out after several tests.

11-30-2012, 01:42 PM	#5
Patrick Olsen NASIOC Supporter Member#: 120 Join Date: Jul 1999 Chapter/Region: AKIC Location: Where the Navy sends me... Vehicle: 1997 Legacy 2.5GT QuickSilver Metallic	The problem as you're describing it sounds like an internal head gasket leak, causing the cooling system to be pressurized by combustion chamber pressure. Not that it should matter for this problem, but did you put anything in other than distilled water? Even if the car never sees cold temperatures, it's a good idea to have at least some coolant or coolant conditioner in there to minimize corrosion and keep the system healthy. And for the SOHC engines it's a good idea to use the Subaru-specific coolant conditioner (which may be designed to be use with Subaru coolant, I'm not real sure on that as I don't have one of those engines).

11-30-2012, 10:29 PM	#6
Rally STi Guy Scooby Newbie Member#: 210109 Join Date: Apr 2009 Chapter/Region: TXIC Location: Wise County Vehicle: 2004 STi PSM	I would agree with you that it sounds like the gasket is leaking but if that were the case I would think that I would have to add coolant/water to the system because it had gotten blown out and replaced with combustion gases. Am I not thinking about that right? When the engine cools off there isn't any room in the system to add more coolant/water. I had put in straight water just to test the system. I didn't want to have put coolant in only to have to take it apart again and have it go all over the place. My father has put coolant in the system currently until I work on it again when I'm home for Christmas. The felpro head gasket was three sheets of metal. Has anyone used them before or a similar style and have had any problems. My current plan for redoing the head gasket it have both heads decked by a machine shop, new head bolts and buy OEM head gaskets.

12-01-2012, 04:25 PM	#7
Patrick Olsen NASIOC Supporter Member#: 120 Join Date: Jul 1999 Chapter/Region: AKIC Location: Where the Navy sends me... Vehicle: 1997 Legacy 2.5GT QuickSilver Metallic	Understand about using just water for the sake of testing. I checked Fel-Pro's website before I posted initially and their gaskets are MLS (multi-layer steel), which is the same thing as OEM, so there really shouldn't be an issue there. When I've had internal head gasket leaks on my car, the only time I would actually lose coolant was if I pushed the car hard enough / long enough that it would overflow the overflow bottle and blow coolant all over the driver side of the engine bay.