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Air in radiator/recovery tank overfilling
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DIYGUY
New User
May 30, 2009, 12:55 PM
Post #1 of 3
(4428 views)
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Air in radiator/recovery tank overfilling
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My wife and I have been baffled by a problem with one of our cars for some months now.
The car is a 1991 Subaru Omega 1.6 engine, two wheel drive, 300,000 kilometers (180,000 miles), no A/C. My wife drives the car. Her initial experience that may or may not be related to this problem is that from time to time there was a whirring sound coming from the engine compartment along with what she experienced as a blast of heat coming into the car interior from the front of the car. When she pulled over to the side of the road, the whirring stopped, along with the excessive heat. The temperature gauge never went up over about half way, but she has suspected since she bought the car 11 years ago that gauge has never worked properly. I heard the whirring noise once, and it was my impression that it was coming from the water pump.
I looked the car over, and could see no leaks, but the radiator looked really bad. I pulled it out and took it to a radiator shop who pressure checked it and said it was ok, but alot (30%) of the fins were missing, tubes bending. I bought a new radiator rather than putting in the old decrepid one thinking the new one might keep the engine from overheating if that was what it was doing, and the car really needed a new radiator. I also replaced the radiator cap at that time.
Replacing the radiator did seem to improve the situation. There doesn't seem to be anymore whirring noise happening and no intense heat experienced in the car interior. What is happening now, however (and was likely happening all along), is that coolant is being pushed into the coolant recovery tank when the car is used, but the coolant is not being returned to the radiator when the engine cools off. After the engine cools off, the radiator is more or less low on water, depending on how much it was driven. That water seems to be in the recovery tank. When I take the radiator cap off, no water flows back into the radiator from the recovery tank, but when I blow on the tank fill hole, coolant flows back into the radiator. Apparently the full line on the tank corresponds to the full level of the radiator. I have taken off the recovery tank and hose and made sure the hose and tank outlet are clear and allow for full flow of coolant.
Cooling system hoses have been checked and tightened when hot by a mechanic who also verified that the electric fan was working properly. I had asked the mechanic to diagnose the problem, but didn't ask him to run a pressure check which I guess I should have done, because he didn't do that and didn't diagnose the problem.
My next move is to replace the thermostat, thinking that possibly there is overheating and boiling happening because of a malfunctioning thermostat. Also the thermostat has not been replaced in some years so that will not hurt. It's a cheap easy job to do.
If the new thermostat doesn't fix the problem, I'm not sure what my next move will be. One thing that I have not said, is that I have noticed in driving the car for maybe just five minutes or so and taking the radiator cap off there is a gush of coolant that come out of the radiator, gushing up several inches, but of course not hot.
I guess a pressure check would be the next step, thinking there might be a leaking head gasket or a cracked block or head. I would likely have to go back to the mechanic for that.
I think that pretty well sums up the history here. Oh one last thing is the temperature gauge that my wife questions. Wondering how I can check that out to see if it is working properly. I just looked at it with the car sitting cool and it is reading all the way cold right now.
Thanks for any suggestions.
Al
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Hammer Time
Ultimate Carjunky
/ Moderator
May 30, 2009, 1:06 PM
Post #2 of 3
(4425 views)
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Re: Air in radiator/recovery tank overfilling
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There is a good chance that you may have a blown head gasket, especially if there is an overheat in the car's history. Pressure testing would be the first step but you may have to do a chemical test or use a gas analyzer to find out for sure.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Asilus
User
Jun 9, 2009, 8:57 PM
Post #3 of 3
(4373 views)
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Re: Air in radiator/recovery tank overfilling
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If it was the thermostat and its rusted shut, the car will overhead in 5 or 10 minuts regardless if your moving, build pressure and blow it into your reservoir, probably to a point of blowing the cap off the reservoir and overflowing. There might also be a large air pocket trapped in the radiator taking up space and forcing water out into the reservoir as well, also a cause of overheating.. if you want to check to see if temp guage works, pull the fuse on ur radiator fan and turn ur heater on and let ur car idle for a bit, first sign of heating past the norm, turn it off and reinsurt fuse...
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