Webber Posted July 18, 2005 Share Posted July 18, 2005 I have a real puzzle on my hands. I've been reading other people's posts and trying solve this case, but I need to call in the experts. The crime a bizarre overheating Subaru; The victim is a mature 1990 Subaru Legacy. About 3 weeks ago I was commuting to work and I noticed when I reached my destination my car was overheating. The radiator was low on water. Simple solution, at the time, let the car cool, add water until full, and drive home after work of course. The car ran great for about 4 days, no problems. The car began to overheat, but the strangest thing happened, my heater inside the car went cold. As the temp gage rose to red, it stopped suddenly and dove back down to normal; at the same time, the air from the heater became hot again. This yo-yo effect happened 2 or 3 times; now it just goes into the red and the hot air turns cold. Here's what I've tried... 1. Changed the thermostat twice, have a new stock thermostat from dealership. 2. Changed water pump, plus timing belt, No regrets; the belt needed it after 170,000 miles of use. 3. Bought new radiator cap. 4. Took radiator out and had it tested, everything checked out great. 5. Tried bypassing heater-core, overheating still occurred. 6. No oil on water, no water in oil. 7. Pulled some off my hair out. 8. Burped system and this seemed to work, but after driving for a mile, it filled the reservoir, and at the same time, the heater air turned cold. When the car over heats, it's always after driving never at start-up and pro-longed idle. Also, the upper radiator hose is extremely hot, but the rest of the radiator is cold to the touch as if the engine isn't even running. The lower radiator hose is also cold. I'm going to try and bleed the system again this morning because it seems like there is a pocket of air between the two hoses, possibly because all the coolant is now in the reservoir. But, after the engine cools the radiator takes back the coolant from the reservoir. Any suggestions to this mysterious overheating? I saw some similar posts from 2002?, but the end result was never revealed. Link to comment Share on other sites More sharing options...
RallyKeith Posted July 18, 2005 Share Posted July 18, 2005 Well, I hate to tell you this, but when the car overheated the first time it damaged/blew the head gasket some where. What is happening now is that you randomly get a break in the headgasket seal that causes the cooling system to become pressurized by the the engine's gases (intake charge/exhaust gasses) When that happens the coolant stops circulating. This causes the temp gauge to go up and the heater air to go cold. Heat goes cold because there is no more hot collant flowing across it to heat it up, and the temp gauge goes up because there is nothing flowing through the engine to carry the heat away to the radiator. Sorry, but I'm pretty sure you need a head gasket job. Keith Link to comment Share on other sites More sharing options...
Webber Posted July 18, 2005 Author Share Posted July 18, 2005 Thanks Keith for the answer I wasn't hoping for. I also appreciate the technical description of what was actually happening. There's nothing worse than having a brain teaser with no answer. I guess my 2.2L engine did well; It has 266,000 miles or more on the odometer and this will be the first head gasket replacement. What do you think the difficulty level of this job will be? I'd rather do the work myself to save money, and because I know I can once I get started. My wife wants to chuck the car and start over with another one, but I'd hate to have to go in debt again or inherit someone else's problems. I had a feeling it was the head gasket, but couldn't understand how it was affecting the heater; plus, it was much easier to live in denial. Link to comment Share on other sites More sharing options...
Suzam Posted July 18, 2005 Share Posted July 18, 2005 Have you made sure that you burped the cooling system properly? An air bubble can possibly cause intermittent over heating. Our MY95 2.2 had a bubble that caused the heater core gurgle and give less heat output. Link to comment Share on other sites More sharing options...
Webber Posted July 18, 2005 Author Share Posted July 18, 2005 I think I burped it correctly; I filled the radiator with the bleeder valve open; started the vehicle; until the thermostat opened; and added fluid until full. I let the car idle and squeezed the radiator hoses as well as the heater core hoses to get all the air out. At this point, I put the cap on and held the accelerator to 2,500 RPMs for 2 minutes. I shut the engine off a few minutes after all this and at this point the heater has been blowing out hot air and the temp gaged stayed below the halfway mark. I let the car cool down and during this time the reservoir stayed at the same level. I opened the radiator to see if I needed to add water. I added a little bit and started the process over again. I just recently took it for another test drive, and about half a mile away, the heater inside the car started to cool and I immediate headed back home. When I reached my driveway, I was in the red and cold air was blowing from the heater. I'm starting to become a firm believer that it's the head gasket. The problem is the nearest mechanic, besides my amateur self, is 20 miles away. I live in a rural area. So I'll need to tow it over country roads to get it pressure tested, and at this point, I don't know if it will show up on the test if it needs to move to react the way it does. Bummer, huh? Now, I'm doing some research on the topic to see what the next step is. Link to comment Share on other sites More sharing options...
Cougar Posted July 19, 2005 Share Posted July 19, 2005 You do have the classic symtoms of head gasket failure unfortunately. Have a block check done to verify it. It is a cheap test to do. Link to comment Share on other sites More sharing options...
Suzam Posted July 19, 2005 Share Posted July 19, 2005 Ouch on the mechanic's distance. I was hoping you hadn't burped it correctly, it would be a simpler and cheaper fix than a headgasket. Keep us posted as to what you find out and hopefully you have some good luck. Link to comment Share on other sites More sharing options...
blackbart Posted July 19, 2005 Share Posted July 19, 2005 I went through the same thing when the HG went on my 90 legacy, turned out that the swing in the temp (as shown on the dashboard)was the air in the system causing the coolant to get "stuck". When you sharply increase or decrease you speed you can "splash" the water through the air pocket. Now the cooler coolant that was stuck in your radiator makes it's way to your temp sender and it appears that the problem is comeing and going. Link to comment Share on other sites More sharing options...
Setright Posted July 19, 2005 Share Posted July 19, 2005 Yes, it sounds like the headgaskets are tired. My EJ22 behaved exactly like yours when it blew a gasket at 120K miles. Do the work, keep the car. You'll miss the EJ22 if it goes. Link to comment Share on other sites More sharing options...
Spazz698 Posted July 19, 2005 Share Posted July 19, 2005 I wonder if this is the same issue Im having with my car? (sorry I dont want to start a new thread it's so similar!) last 3 days my temp gauge has been rising higher than it usually does, today it actually got about 3/4 of the way up. Now it's been hot as hell here the last 3 days (80+, it was a lil over 90 today) Every time I notice it's up I'm stopped (today when it got up there I was stuck in traffic) the overflow tank has just as much coolant in it as its ever had, no oil in there at all, but I do have an external hg leak, small leak but I'm planning to make this part of my compentcy thing for school in fall as my next quarter involves this. I've checked the oil too btw, and I cant find anything wrong with it, the color's fine. So Im assuming I should burp it and see what happens? I mentioned this to my dad and my ex and both said it was normal since it's been so damn hot and my ex's car (honda) was doing the same thing for the last 3 days as well. Link to comment Share on other sites More sharing options...
Webber Posted July 19, 2005 Author Share Posted July 19, 2005 Two years ago I had an overheating issue only when I would drive up hills. I pulled the radiator out, hoping it wasn't anything else. It turned out the radiator was 65% clogged and that was at 220,000 miles. I bought a new radiator and hoses for around $150 altogether and fixed the problem. Back then, I just filled the radiator with 50/50 and let the engine idle and topped it off after the thermostat opened. Problem solved. Two years later, the effort I'm going through to extract air bubbles seems a little extreme compared to the past. I'm unfortunately becoming a firm believer in the head gasket theory. I was thinking of throwing some stop leak in the radiator, hoping it would be able to limp it into a repair shop for a diagnostic. If necessay, I'll rent a auto transport and have my 68 Chevy tow it in for the test. The debate is; fix the head gasket myself at 266,000 miles on the odometer, or find something else. This Subaru has been a great car. I've only had to change the altenator, starter, timing belt, and water pump; everything else came with the car at mile 0. I also would like to thank everyone for their posts. It has made this diagnostic process so much easier. It also makes me proud to be a part of the Subaru community. I'll keep you posted on what happens with the car, but I won't be able to take it in until next week. And if any of you are having the same issue, I'll be sure to post the results. Link to comment Share on other sites More sharing options...
Muppit Posted July 19, 2005 Share Posted July 19, 2005 Hey, I have had the exact same problem with my 2.0 1990 Legacy. I would've bled the cooling system at least 5 or 6 times trying to figure the problem, and being a student the income doesnt let me take trips to the mechanic willy-nilly. So, I've been driving round with no thermostat, and it has never overheated. Our winter here gets down to sometimes 2 or 3 celcius but average bout 8 or 9 first thing. Whether its doing permanent damage I'm not sure, but what else can I do? It rarely but will sometimes get up to normal operating temp but most of the time sit around a quater. Anyway, whe I did get it into the Suby mechanic, he forgot to replace the thermostat before bleeding, but did a pressure check and this returned positive. But to my point, you asked how big-a job it'd be to do yourself, I don't know if you've discovered them yet, and I don't have the web address on me just at this time, but there are a heap of service and technical manuals that some legend scanned in and put up on the web. A quick search would probably return results, and these would be a great place to start, with special tool lists, diagrams and instructions....plus others have posted their step-by-steps too. Just my 35 cents, cheers muppit P.S. THESE pages: http://www.main.experiencetherave.com:8080/subaru_manual_scans/ Link to comment Share on other sites More sharing options...
Webber Posted July 19, 2005 Author Share Posted July 19, 2005 Thanks, Muppit. I'll try and see what happens. If it works, I could at least get it into a repair shop to get it tested. Mark Link to comment Share on other sites More sharing options...
idosubaru Posted July 20, 2005 Share Posted July 20, 2005 if you run it for too many miles (like 100's even 1000's possibly) the head will be destroyed (or expensive to fix). the head will have a notch melted or warn into it where the leak is if you drive it while it's hot too much. best to keep it running as cool as possible (remove thermostat like mentioned above) to prevent permanent damage. the heat is bad for the oil and bearings as well. i've done a bunch of older model subaru head gaskets. it's a straight forward job, but it will require tools, time and experience is a very helpful attribute as well. a rebuilt or used motor might be a better option than a new (or used with unknown history) car. Link to comment Share on other sites More sharing options...
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