Racingmax53 Posted February 3, 2019 Share Posted February 3, 2019 Hey guys! I was driving my Auto 98 Legacy Outback wagon today for a while. And I noticed the coolant temp gauge pegged at "H". I immediately pulled over, turned the car off and opened the hood to see if I can see any issues. The electric fans were spinning, the upper radiator hose was hot to the touch but looked normal. And the radiator was not venting or indicting an actual overheat. There was also no coolant burning smell from the car or any smoke coming from the pipe that I could see. I started the car for a split second to see if all the belts were spinning as they should. And I couldn't notice any blaring problems. I let the car sit for about 5 minutes and hopped back in to turn the fans back on, and the temp gauge was all the way at the bottom, even with the accessories on! I started the car and it jumped right up to normal operating temperature, and started to climb, so I shut it back off. I let the car sit for about 15 minutes and hopped in to drive the car to a bigger parking lot just in case I had to call a tow truck. The temp gauge didn't move from the normal operating temp for about 5-10 minutes. I had the heat on full blast, and I noticed the temperature of the heated air would fluctuate from cold to burning hot in about a minute. The gauge would rather quickly start climbing to "H" again and then go back down. It did this the entire 20 minute drive home. Not hitting "H" but getting a little too close for comfort. I am thinking it is either the thermostat or the coolant temp sensor itself? There are no lights on the dash (i.e. check engine, or coolant). I haven't noticed any fluid coming out of the car or any abnormal sounds or smells. I would have liked to have had access to an inferred thermometer to check the temp of the upper radiator hose. The car has about 150,000 miles on it. Any ideas what I should check next? Thank you in advance! EDIT: I have not had a chance to open the radiator yet, the car has been sitting for about 20 minutes and the temp gauge reads slightly under operating temp. EDIT Squared: It was a bubble in the cooling system! I found this other forum post with the issue and the solution. https://legacygt.com/forums/showthread.php/no-heat-heat-gauge-shows-hot-156748.html Link to comment Share on other sites More sharing options...
Brighton96 Posted February 4, 2019 Share Posted February 4, 2019 It could be the actual coolant itself being broken down and not cooling as it should. Just do a full coolant service and see what that gets you. Replace the thermostat and seal with OEM parts only, you can use any coolant you want and make sure to bleed it properly/fully before driving it. Link to comment Share on other sites More sharing options...
doublechaz Posted February 4, 2019 Share Posted February 4, 2019 Classic for large amount of air in the system. Now you have to find out how all that air got in there... Link to comment Share on other sites More sharing options...
Racingmax53 Posted February 5, 2019 Author Share Posted February 5, 2019 It could be the actual coolant itself being broken down and not cooling as it should. Just do a full coolant service and see what that gets you. Replace the thermostat and seal with OEM parts only, you can use any coolant you want and make sure to bleed it properly/fully before driving it. The car is scheduled for a service this Friday. It hasn't been to a QUALIFIED mechanic since I bought it. Doesn't hurt to have an independent Subaru mechanic look over the whole car! I took the car out yesterday (first time I'd gotten snow in years and it was 8 inches!) I had to play. And the car was driving fine for a few hours! Then the same symptoms showed up. And I managed to limp the car home. I was watching the temp gauge like a hawk the whole two hours and it was fine. I'm curious what happened at that moment to either create or free that air bubble from somewhere else in the system. I was unable to open the hood as it was frozen shut to check the radiator. Classic for large amount of air in the system. Now you have to find out how all that air got in there... Yeah I'm pretty worried about how that air got into the system. I haven't noticed anything strange (i.e. smoke from the exhaust) to indicate the the problem that shall not be named on a EJ25... head gaskets... They were replaced less than 20 thousand miles ago, so hopefully it is just a small hole in a radiator line or, at worse the water pump. I'll keep this thread updated just in case! Link to comment Share on other sites More sharing options...
moral hazard Posted February 6, 2019 Share Posted February 6, 2019 I've seen plenty of blown headgaskets without smoke from the exhaust. A really common way bubbles get into the coolant system is via combustion gases entering the coolant from blown headgaskets. But fingers crossed you just have a pinhole leak in a hose somewhere causing your issue. Link to comment Share on other sites More sharing options...
rknrol3113 Posted March 4, 2019 Share Posted March 4, 2019 Hey guys! I was driving my Auto 98 Legacy Outback wagon today for a while. And I noticed the coolant temp gauge pegged at "H". I immediately pulled over, turned the car off and opened the hood to see if I can see any issues. The electric fans were spinning, the upper radiator hose was hot to the touch but looked normal. And the radiator was not venting or indicting an actual overheat. There was also no coolant burning smell from the car or any smoke coming from the pipe that I could see. I started the car for a split second to see if all the belts were spinning as they should. And I couldn't notice any blaring problems. I let the car sit for about 5 minutes and hopped back in to turn the fans back on, and the temp gauge was all the way at the bottom, even with the accessories on! I started the car and it jumped right up to normal operating temperature, and started to climb, so I shut it back off. I let the car sit for about 15 minutes and hopped in to drive the car to a bigger parking lot just in case I had to call a tow truck. The temp gauge didn't move from the normal operating temp for about 5-10 minutes. I had the heat on full blast, and I noticed the temperature of the heated air would fluctuate from cold to burning hot in about a minute. The gauge would rather quickly start climbing to "H" again and then go back down. It did this the entire 20 minute drive home. Not hitting "H" but getting a little too close for comfort. I am thinking it is either the thermostat or the coolant temp sensor itself? There are no lights on the dash (i.e. check engine, or coolant). I haven't noticed any fluid coming out of the car or any abnormal sounds or smells. I would have liked to have had access to an inferred thermometer to check the temp of the upper radiator hose. The car has about 150,000 miles on it. Any ideas what I should check next? Thank you in advance! EDIT: I have not had a chance to open the radiator yet, the car has been sitting for about 20 minutes and the temp gauge reads slightly under operating temp. EDIT Squared: It was a bubble in the cooling system! I found this other forum post with the issue and the solution. https://legacygt.com/forums/showthread.php/no-heat-heat-gauge-shows-hot-156748.htmlYeah the bubble in the cooling system is where the rest of the antifreeze is supposed to fill FYI I need to replace the radiator cap with original pressure a low pressure cap will leave air pockets and cause the same condition Sent from my SM-S327VL using Tapatalk Link to comment Share on other sites More sharing options...
mangry Posted March 5, 2019 Share Posted March 5, 2019 I don't think you mentioned if you had changed coolant or if someone had recently. But it also sounds like a sticky thermostat. Even new thermostats can fail and exhibit similar symptoms. Link to comment Share on other sites More sharing options...
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