Overheating 96 subaru legacy


OK well recently I bought this car for good price with bad transmission problems. since I have one lined up it was not an issue. So i brought it home and found that it was the CV axles so I replaced them both and transmission was fine. The car ran fine so I did a tune up on it. after a week of driving it all around I decided to go and visit a friend about 200 miles away. When coming home the next day I stopped at an intersection and noticed the car had turned off. so I rolled it accross the street and used a hose to fill up the radiator, was shocked to see it take in so much water. So a few days later my uncle wanted to do a compression check on it and chemical. when going for test drive we found the one side of the radiator was at 265 degrees and the other 113 so I replaced the radiator since it had a leak in it and someone used stop leak to fill up the leak. I now have a new radiator and water pump along with a thermostat installed. To my supise I took it for a test drive and it overheated about 10 minutes into the drive. had it towed in idle while running at normal operating temp. took for another drive around the block and about 7 minutes later it shot back up. so I waited untill it cooled down a little and during the 4 blocks back home I had to stop 3 times and wait 5 minutes at a time. so im asking what these symptoms may indicate…? during idle it seems to run for 15-20 minutes without an issue watching the needle. the fans both start at normal time. So im looking for any clues and advice …thanks!


im asking what these symptoms may indicate…?

To me it sounds like a head gasket. Likely the first overheating was the last straw.


last straw? im hoping for second or third to last straw.


Check the lower radiator hose. There have been cases where the lower hose will collapse under the vacuum from the water pump, which would happen at higher engine speeds, since the pump is working faster. And, therefore, the coolant wouldn’t be getting circulated.

Second possibility is air in the coolant. If there’s a lot of air, it could cause the water pump to cavitate (not pump any coolant) and again, would cause overheating.

Also, is there any other signs of overheating aside from the dash gauge? If not, I wonder if maybe the temperature sensor isn’t working right.

Good luck.


haha yeah its definately overheating it shoots up coolant on the underside of my hood from the overflow. the one thing we seem to notice is that the top radiator hose on the left side does not seem to be full I mean it gets very hot but unlike any other car I dont feel any pressure so if it is air how would I get it out? someone has also mentioned something about a vaccume leak could cause this? anyways if anyone knows about the air possibility let me know how I would take care of this…thanks!


Did you replace the radiator cap when you replaced the radiator? If the cap’s not holding pressure, the coolant boils over at a lower temp. It’s not an expensive fix and it’s worth a try. I hope it’s not the head gasket.

Good luck,

Ed B.


I doubt its the cap cause its shooting up through the overflow through a small hole I guess made for that reason. And also I see nothing in the oil to indicate a cracked block whew! no bubbles or anything milky looking. but hmm yeah ill look at the cap in a few.


It’s shooting out the overflow tube because it’s boiling over, which could be because of a faulty rad cap. The cap isn’t holding the proper pressure, resulting in a reduced boiling temp for the fluid, and the aforementioned coolant escaping from the overflow tube.

Also, just another thought: Did you put in a 50/50 mixture of pure anti-freeze and distilled water? If the ratio is off then the boiling point also is reduced, causing boil-over of the coolant.

To get rid of air, and easy way to do it is to take off the rad cap (when the engine is cold) and run the engine with the heater on high for about 5-10 minutes. Any air will escape out the top of the rad where the cap goes.


we filled it with the antifreeze coolant half way and then topped the rest with water and coolant mixture. also if my heater core is bad will turning on the heater full be of any use? so I dont need to flush my system with any kit to get the air out? thanks again!


You filled the system halfway with antifreeze, then the rest with mix of water and anti-freeze? That might be your problem there, there’s too much antifreeze, probably a 70/30 mix, which is bad. Get a cheap coolant tester, test your coolant. If it shows and incorrect mixture, drain some of the coolant out, and add water, then retest until the mixture is 50/50 water and coolant.

Heater core: how is it bad? A leak? A blockage? Either of those, or other things, can cause overheating, since the heater acts as a second radiator. Even when the heater’s not being used, I believe coolant is still being pumped through the heater core.

Anyway, you need to make sure there’s a 50/50 antifreeze/water mixture in the cooling system, since it’s the most effective ratio you can get, and therefore is best for cooling.


yeah a friend was telling me to try and bypass the heater core and see if that makes any difference. cause I remember when I took it on that trip it was cold at night and my heater would just blow cold air. so that is what im leaning towards. I also have a catalitic issue which may cause some overheating but I would not think this much. so yeah im leaning towards the heater core for now. anyway to test without doing a bypass cutting the hoses? thanks!


Maybe take out the hoses in the engine compartment where they enter the firewall, and get a hose connector the right size, just connect the in/out hoses together, and attach them with some wire to something in the engine so they won’t fall onto something they shouldn’t. I figure that would work, at least temporarily.


well as last resort I went back with my old thermostat and figured I could drive like before. Well NO! after 8 miles of driving on the highway I pulled over to check my car and saw nothing wrong so after a few minutes rest in the park I was on my way home but NO! about 20 feet into my trip back home my dial hit up to HOT! well so much for all your advise but thanks again. So I have now gave up and decided to inspect my heads and see what may need some work done. I am now down to the engine block and with heads seperate. And yes I used the sequence for losening them. So I could use some more advice as what to look for. I might just as well since I have it all apart soon do a whole engine overhaul. Im actually suprised at how simple things have been so far…knock on wood…so thanks again


If you have a catalytic converter problem related to clogging then this is much more likely to cause overheating than a heater core. We had a car come into the shop one time in which the exhaust manifolds were glowing red and the paint was starting to bubble on the hood from the heat. Clogged converters, and yes, the engine was absolutely barbecued. It amazed me that he made it to the shop even at 10 mph and billowing smoke.

Don’t take this personally, but it sounds like you’re grasping here. You’ve pulled the cylinder heads and are dismissing the radiator cap because it looks good? How does one eyeball a radiator cap. A cooling system pressure tester, available for free use by AutoZone I think, will test a cap.

Air pockets can also cause erratic operation of the temperature gauge.

There are multiple ways of inspecting for head gasket problems without tearing things apart.
Compression test, cooling system pressure test, hydrocarbon test, vacuum gauge, etc and they should all be performed IMHO to weed out all doubt.

I can give you a few tech tips on the heads and total engine overhaul if you desire, and again, I do not mean my comments in a bad way.
(Just curious; do you know offhand what the compression readings were when this was done?)


Unfortunately (for the OP), I agree with JEM and think there is headgasket leak causing this to happen. I suggest you have the coolant checked for exhaust gases.


I owned one of these and after putting in a new water pump had the same problem. I bet you are useing the 15$ service manual. It just says fill rad with cap off. That wont work. If you get the Factory service manual it shows a little plastic plug on the passanger side top of the rad, can take it out with a phillps screw driver. This will let out the traped air in the system that is messing things up. I also used a small funnel to fill this part up too get every drop in I could. Good luck, get on the net and buy a factory service manual.