My 1998 Subaru keeps overheating I replaced the thermostat and I have drained air bubbles out via the plug on top but it still overheating

When cold fill the radiator with water and leave the cap off. Make sure that you have all the air out.
Start the car and watch the radiator, you are looking for air bubbles coming out of the radiator. If you have a steady stream of bubbles appearing you have a blown head gasket.

the cooling system will not fill completely if the bleed plug located @ the highest point of the system up is not opened when you are filling up..that plug could be @ the radiator , but normally is @ the top of the system where the top rad hose are..replace the plug after bleeding the system is complete..

With the engine cold remove the radiator cap. Start the engine. Watch the coolant. If you see bubbles constantly perkulating out of the coolant than you most likely have a head gasket that has failed. If you don't see a constant perkulation of air bubbles it probably wouldn't hurt to replace the upper hose and see if the problem is resolved.

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Most likely you put the thesmostat in upsid down. Good luck

On my 1998 subaru legacy outback limited I replaced the thermostat and did a radiator flush and fill and it overheated when I tested it. It basically overheated because there was air in the system. I relieved it by running the car and partially unscrewing the black plastic relief screw on the top left of the radiator(looking at it from the front of the car) until it stopped hissing and fluid started coming out then I screwed it back tight and I've never had a problem since. I think subarus are pretty fussy with this because my mechanic even missed it when they did the head gaskets.

i have a 2000 olds intrigue thats been overheating alot lately the other day my drain plug for my radiator came on the way to work so i lost all my antifreeze on the way, i got to work and wound getting another plug to replace...the one that came out...topped off antifreeze...anyhow i go home and car overheats on the way home...i took it to a radiator shop today and they checked for, leaks, checked the water pump, pressure tested it...and they told me that the only thing they found was a airlock, but however the guy did recommend taking it to a mech and having it checked for a blown headgasket, so i go home today and i noticed my temp gauge going up and down on the way home it would get hot then cool down then get hot again...the car did eventually start to overheated so i pulled over and let the car cool down...i know this is getting frustrating, so do you have any recommendations or solutions as to whats cause the car to overheat.

clogged radiator,fan not cooling ,stat or pump even though defective belt slipping on pump

Who did the replacement of the parts? Was it done at a shop or at home? Do you know if the cooling system was "burped" after the parts were installed and the coolant was refilled? If you're not sure, burp the radiator. This is easy to do. Jack up the vehicle so that the thermostat is angled upward. Start the car and let it idle until it's 3/4 of the way to overheating, then shut it off and allow it to cool down somewhat. Then pop the cap, let the coolant drain down, and refill it. Restart the vehicle and repeat the process, until the coolant level doesn't drop anymore.

What you're doing is this - anytime the cooling system is opened up, especially when the fluid is drained and parts are replaced, air gets into the system. When you reassemble and refill with coolant, you trap air bubbles in the system. Since the system is sealed, it operates under pressure. As the car runs, the coolant and the air bubbles are circulated. The bubbles get caught behind the thermostat (if you have it angled upward) and keep it from opening. This causes the engine to heat up to the point of overheating. You want to allow it to get about 3/4 of the way to an overheat so that you know the air bubbles are blocking the thermostat. Shutting down the car stops it from heating up to the point of damage, and allows the system time to cool off so that when you pop the cap, you don't get an explosion of coolant in your face. Once it's cool enough to open the system, you open it and release the pressure. This allows the thermostat to open and bleed the bubbles upward to the open cap, where they "burp" into the air. The space they took up fills with coolant, which is why your coolant level drains down. You top it off and repeat to make sure that all the bubbles are out. You'll know you're in good shape when you let it run and it gets to operating temperature and doesn't overheat anymore. Let it cool that final time, open the cap, and since you have no air pockets left in the system, nothing will burp out and your coolant level won't decrease. Then you should be good to go - put the cap back on and drive away happy.

Hi,

I had the same problem with my 1993 Liberty LX. Remove the thermostat (located inside bottom radiator hose engine connection - take the connection off and thermostat is inside). Reassemble (minus thermostat), reconnect bottom hose. Slowly (very, very slowly) refill the radiator and remove the bleed plug ( located beside the top hose connection to the radiator - a black square plug with a phillips head cross in the middle). When the radiator is full and clear water (no air bubbles) is coming out of the bleed point, replace the bleed plug and then the radiator cap.

Run the engine for five minutes (approx) or until normal engine temperature is reached. Allow the engine to cool down and recheck the water level - fill if necessary ensuring that the bleed plug is open and clear water is coming out of that point. Replace Bleed plug and then radiator cap. Run engine for five minutes (approx) and then test dive. If the engine overheats keep filling the radiator until there are no air bubbles coming from out of the bleed point.

This fixed my overheating problem. Good luck and safe motoring.