edrach Posted June 22, 2006 Share Posted June 22, 2006 My '94 Impreza, EJ18 engine, 126K miles. All right, why should my coolant be overflowing the expansion bottle? I got home last evening and everything seemed normal. Car ran fine all the way home (one hour drive, mostly highway). Walking by the front of the car in the driveway and I could smell the ugly aroma of coolant. Checked the bottle and it was full to the top. Evidence of draining out the overflow right below the hose; not a little, a lot. Both upper and lower hoses are hot to the touch. The radiator is lukewarm at best anywhere I can touch it. Engine is not inordinately hot considering I've been driving for an hour. No CELs, temp gauge is where it belongs, car runs just fine; no other temp related issues in the last five weeks since I bought the car. Any thoughts? Quote Link to comment Share on other sites More sharing options...
Jerry DeMoss Posted June 22, 2006 Share Posted June 22, 2006 Sounds to me like there may be a pocket of air in the cooling system somehow.Maybe the coolant isn't able to completely make the cycle through and purge out the air,and such making the excess coolant that has no where to go but to the over flow bottle. Just a thought. Another idea is that your radiator cap is failing to hold pressure and making the extra coolant go to the bottle.Good luck.I am anxious to hear what it turns out to be. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 22, 2006 Author Share Posted June 22, 2006 Another idea is that your radiator cap is failing to hold pressure and making the extra coolant go to the bottle.Good luck.I am anxious to hear what it turns out to be.Radiator cap looks okay; I checked it and nothing appears stuck, but I'll be replacing it with new anyway. It would be a cheap fix. Quote Link to comment Share on other sites More sharing options...
nipper Posted June 22, 2006 Share Posted June 22, 2006 First question, any work done to the engine recently? Since your temp gauge is staying reasonable, for now we will discount the HG idea, but air bubbles in the cooling system just dont appear out of no where. Cap is a good idea. When was the last time the cooling system was serviced. Did you feel both hoses. DO you have heat? nipper Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 22, 2006 Share Posted June 22, 2006 i'd replace the cap too, it's cheap enough to "give it a try". hope that does it. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 22, 2006 Author Share Posted June 22, 2006 First question, any work done to the engine recently?Since your temp gauge is staying reasonable, for now we will discount the HG idea, but air bubbles in the cooling system just dont appear out of no where. Cap is a good idea. When was the last time the cooling system was serviced. Did you feel both hoses. DO you have heat? nipper No recent engine work done. I bought the car about 6 weeks ago and had the car checked by Smart Service; they found all four cylinders had good (and uniform) compression and no HC's in the coolant. I did feel both hoses, and they were both hot. Last time I used the heater (in the past week), I did have lots of heat; I needed to crank it back to minimum. Quote Link to comment Share on other sites More sharing options...
nipper Posted June 22, 2006 Share Posted June 22, 2006 No recent engine work done. I bought the car about 6 weeks ago and had the car checked by Smart Service; they found all four cylinders had good (and uniform) compression and no HC's in the coolant. I did feel both hoses, and they were both hot. Last time I used the heater (in the past week), I did have lots of heat; I needed to crank it back to minimum. ok so we can rule out HG issues for now. Ild go with the cap an see what happens, also wouldnt be a bad idea to replace the coolant anyway along with all the other fluids. nipper Quote Link to comment Share on other sites More sharing options...
edrach Posted June 22, 2006 Author Share Posted June 22, 2006 I took the time this morning to check out the system a bit. I poured some of the coolant out of the reservoir back into the radiator with the engine idling. Oddly, it only took coolant until I got to the full mark on the reservoir. I let it idle for about 5 minutes, no bubbling out of the radiator. When the coolant level started to rise I put the cap back on. Another 10 minutes of idling, upper hose getting hot; radiator and lower hose still relatively cool. I opened the throttle by hand to about 2000 rpm and after about 3 minutes of that the fan came on. Upper hose very hot; radiator and lower hose hot but not as hot as the upper. Fan cycled off and stayed off for next 5 minutes and I opened the throttle again until the fan turned on again. I noticed the overflow level went up about 1" but no higher. Fan cycled off again. So far everything looks okay. I'm wondering if I might have a sticking thermostat. I'll likely change the coolant with fresh when I change the thermostat and radiator cap. Quote Link to comment Share on other sites More sharing options...
nipper Posted June 22, 2006 Share Posted June 22, 2006 I took the time this morning to check out the system a bit. I poured some of the coolant out of the reservoir back into the radiator with the engine idling. Oddly, it only took coolant until I got to the full mark on the reservoir. I let it idle for about 5 minutes, no bubbling out of the radiator. When the coolant level started to rise I put the cap back on. Another 10 minutes of idling, upper hose getting hot; radiator and lower hose still relatively cool. I opened the throttle by hand to about 2000 rpm and after about 3 minutes of that the fan came on. Upper hose very hot; radiator and lower hose hot but not as hot as the upper. Fan cycled off and stayed off for next 5 minutes and I opened the throttle again until the fan turned on again. I noticed the overflow level went up about 1" but no higher. Fan cycled off again. So far everything looks okay. I'm wondering if I might have a sticking thermostat. I'll likely change the coolant with fresh when I change the thermostat and radiator cap. Wll even if its not sticking, its a good idea to change it. Put in all new coolant, use the 50/50 premix and then lets see whats what. Any idea when the timing belt was replaced? nipper Quote Link to comment Share on other sites More sharing options...
edrach Posted June 22, 2006 Author Share Posted June 22, 2006 Wll even if its not sticking, its a good idea to change it. Put in all new coolant, use the 50/50 premix and then lets see whats what.Any idea when the timing belt was replaced? nipper I was planning to replace it 3 weeks ago, but when we got the covers off, found the belt still had the printing and timing marks still on it. We decided the belt had been done less than 30K ago and didn't replace it then. Everything else looked good there. Interesting thought on the pre-mix: the coolant is VERY green; I suspect it's straight anti-freeze. Quote Link to comment Share on other sites More sharing options...
nipper Posted June 22, 2006 Share Posted June 22, 2006 I was planning to replace it 3 weeks ago, but when we got the covers off, found the belt still had the printing an timing marks still on it. We decided the belt had been done less than 30K ago and didn't replace it then. Everything else looked good there. Interesting thought on the pre-mix: the coolant is VERY green; I suspect it's straight anti-freeze. it always look very green. The reason for the 50/50 is not the mix, but to make sure you dont use tap water. nipper Quote Link to comment Share on other sites More sharing options...
edrach Posted June 22, 2006 Author Share Posted June 22, 2006 it always look very green. The reason for the 50/50 is not the mix, but to make sure you dont use tap water. nipper I always use distilled water when mixing up anti-freeze, but the premix is okay providing it's worth the extra cost. I'll look into it. Quote Link to comment Share on other sites More sharing options...
richierich Posted June 22, 2006 Share Posted June 22, 2006 Ditto. Thermostat & Radiator cap. Have seen a rash of bad radiator caps lately. But I would do the thermostat to be on the safe side, also will get rid of an air pocket if there is one. I take off the upper radiator hose at the radiator and fill the engine up that way, so I am 100% sure of no air pocket. Then I reconnect it and fill the radiator. Quote Link to comment Share on other sites More sharing options...
nipper Posted June 22, 2006 Share Posted June 22, 2006 thermostat from subaru, thats important. My dad always taught me to fill the car with it running and the thermostat open, so ive never had an airpocket in 4 subarus. nipper Quote Link to comment Share on other sites More sharing options...
edrach Posted June 22, 2006 Author Share Posted June 22, 2006 Thermostat and 'cap will be here tomorrow; ordered from Jason at the dealer in Auburn. I have learned that certain items are important to get OEM. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 23, 2006 Author Share Posted June 23, 2006 Good news so far. Came home today and checked the overflow bottle. Coolant had been sucked down to the halfway point between "cold" and "hot" lines. That's a good sign. I'll have a new OEM radiator cap tomorrow and give it a good run then and see how it behaves. I'll think about installing the thermostat later. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 24, 2006 Author Share Posted June 24, 2006 Well, new thermostat, radiator cap and 50/50 mix of coolant went into the car without any issues. Initial test drive went well. Hopefully, no recurrance of the initial problem. Thanks everyone for the helpful hints and suggestions. Quote Link to comment Share on other sites More sharing options...
Setright Posted June 24, 2006 Share Posted June 24, 2006 Sorry, I'm a bit late to the party. I would say the chance of the rad cap being the cause is 90%. My Impreza did exactly the same thing. New cap, and it was back to normal. Good on you for noticing, I reckon this is how a critical overheat scenario starts...slowly the coolant leaves the system and suddenly there's an HG warping overheat. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 25, 2006 Author Share Posted June 25, 2006 Looks like all is well with the cooling system now. Put about 270 miles of highway driving and a rallycross on the car yesterday. Temp guage at halfway the entire way. Checked the overflow bottle and it was near the bottem so I know the radiator cap is pulling coolant back into the radiator. I will top the bottle up to the the low line (I guess that's where it should be on a cold engine) and check on it some more in the future. Quote Link to comment Share on other sites More sharing options...
Olnick Posted June 25, 2006 Share Posted June 25, 2006 Way to go, Ed. And thanks for the update. Aloha. Quote Link to comment Share on other sites More sharing options...
Setright Posted June 25, 2006 Share Posted June 25, 2006 Top off to the FULL mark. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 25, 2006 Author Share Posted June 25, 2006 Top off to the FULL mark. Yea, I figured that out and topped it off to FULL. Thanks. Quote Link to comment Share on other sites More sharing options...
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