July 21, 200916 yr 98 Legacy 2.2L, 150K miles Just installed new radiator and T-stat. Recharged AC. On the highway, the AC suddenly cuts out, blows warm air. Looking at temp gauge, it's at "High". The overflow tank is full and overflowing. Turned Heat to max and the temp went to normal. Tried to bleed the system several times, does this sound like air bubbles in the system preventing coolant from circlating?
July 21, 200916 yr Search for "head gaskets" unless they were recently done using Suby gaskets. And even then if done wrong it could still be HG's. I don't think the AC has anything to do with it. After all how did the original bubble get into the cooling system? If you're sure it was burped it's probably HG's. Welcome to a large club.
July 21, 200916 yr Lets start with something simple, replace the radiator cap. The t-stat MUST be from subaru. Inspect the outside of the radiator and make sure it is in one peice. 2.2's arent known for blowing HG, but at 160K any engine can blow one. The fact that you had heat is a hopeful sign that the HG is ok. Usually you loose heat with a bown HG on a sooby. nipper
July 21, 200916 yr Oops. I'm getting as sloppy as the local mechanic. Overheating I automatically assumed was a 2.5. Yea - try the cheap and easy stuff first. Remember to drain then fill coolant through the top rad hose.
July 21, 200916 yr Author See, I replaced the radiator and T-stat only less than 2 weeks ago. I am not sure I got air out of the system. The radiator and T-stat are OEM Parts. I wonder if the water pump is going bad... it's not making any noises and does not appear to leak.
July 21, 200916 yr BURP!!!! Check for air bubbles. EJ engines are notorious for having trapped air in the system!!!!! Do not drive this car until it's properly bled from your radiator change! Try and get the car to be "nose up" - meaning the front is slightly higher than the rear to help with bleeding. There's a bleeder screw (well on stock Subaru radiators, don't know about if you got an aftermarket one)> on the top passengers side of the radiator. It's plastic. Unscrew it and fill it up until fluid starts pouring out of that. Then tighten, fill at normal. Drive it around at least once, if not more, let it cool and fill some more.
July 21, 200916 yr <<See, I replaced the radiator and T-stat only less than 2 weeks ago. I am not sure I got air out of the system. >> thats the problem, you need to bleed the air out of the system. steps mentioned in the post above.
July 22, 200916 yr Author I found the plastic screw. I think I saw some air come out of it, it was hissing and maybe even bubbles. Am I supposed to put coolant right into that hole or is it just for the purpose of letting air out? Drove it tonight, for an hour after sunset -- no overheating. Good news. The AC was turned on. When I parked, the overflow tank was almost empty which was good, meaning the coolant went into the radiator. I filled the overflow tank, so will see what happens tomorrow. BTW, I checked the coolant for signs of oil and the oil for signs of coolant -- none that I could find.
July 22, 200916 yr that screw is just to let air out while filling through the normal radiator cap area. loosen screw just enough to let air out. sounds like you got it.
July 22, 200916 yr Sounds like you have fixed your problem, if you have problems again check and make sure your A.C. cooling fan is coming on when you turn the A. C. on. It should be the one on the right side of your car as you are sitting in the seat.
July 22, 200916 yr Author I will look at it... The last time it overheated at about 4PM, when it was hot outside and had no problems at 8PM or 9AM, when it was much cooler. I don't know if this has anything to do with it, or just a coincidence. I will drive it again today during the day and see what happens...
July 22, 200916 yr You need to make surre the fans work but they could be interfeering with your diagnosis since I believe atleast one of them runs the entire time the AC is on. When you're checking for overheating I DON'T run the AC. There is an excellent link to a youtube burping video around here somewhere. It along with pulling the front tire nearest the radiator cap onto a ramp and fillign through the top hose has worked everytime for me. Often I don't have it on a ramo though since I've just done an engine swap, HG job, whatever and the car is already setting flat. Only 2 times have I had an issue. One time someone "helped" me when I had run down to the house and filled the rad (not the engine through the top hose). I ended up draining and refilling through the hose. Other time was recently and a bad aftermarket thermostat.
July 22, 200916 yr Author Thanks for the tip -- I understand the idea of raising the front end as high as possible.... I will try just that and try to raise it even higher. No overheating today. I am almost 100% certain it's the bubbles in it causing overheat yesterday... Yes, the fans work.
July 23, 200916 yr FYI how to refill a subaru (or any car for that matter). Make sure the car is on level ground or nose uphill. Open air vent if equiped. Start car. SLOWLY pour 50/50 premix into the radiator till it is full. Wait for the T-stat to open. The coolant will surge out when it opens. Let the car run a bit more then top off the radiator. You can goose the throttle if you want. Fill the Overflow tank to the hot line. Place cap on the radiator, drive the car around the block. Let the car cool off. Check the coolant level in the radiator. Top off radiator in the above manor. Repeat if needed. During this procedure always monitor your engine temp. If you see it rising on the test drive, go home and let the car cool off and topoff. I have never ever had an airbubble in any car using this procedure . nipper
July 23, 200916 yr Author It overheated again today, I must have some air bubbles. My radiator appears full but I will double check. At what point in the above procedure do you close the air vent? Secondly, do you open the radiator cap and let the coolant come out even if it appears full, like in my case? I am not sure I can add any more.
July 23, 200916 yr You close the vent when you drive off. You Have to let the car cool down in a closed system with a full overflow tank. Did you use a subaru T-stat, I dont remember. nipper
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