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Outback overheating

charliemlcharlieml Posts: 8
edited October 2014 in Subaru
I have a 97 Outback that only overheats in cold weather. It has myself and other more knowledgable people quite flummoxed. I bought the car in early 2010 and it would intermitently overheat at idle. Then the warm weather arrived and nothing. This fall it started again much worse ( the overflow filled and leaked ) with the advent of cold weather. It was then I noticed exhaust fumes in the overflow. A friends mechanic suggested I try the Blue Devil treatment which I did and it seemed to clear up the bubbling in the (radiator which is new.) Sealed the head gasket issue. A new and tested thermostat also. After the treatment still problems. He suggested a purge. Parked the car on steep incline and ran the car a little while with the cap off. Helped for a little while and then came back. The weird part is while the temp gauge is way up the heat doesn't work. Is there a switch /sensor that shuts the heater? Would this make for bad circulation? One hose to the heater gets super hot while the other stays normal. Any help appreciated.


  • xwesxxwesx Fairbanks, AlaskaPosts: 9,932
    One of two things is happening. 1. You still have combustion gases getting into the system and it is causing air bubbles that are breaking the flow of the coolant. 2. Your water pump is on the fritz.

    I had a water pump failure on my '96 Outback at approximately 177,000 miles. It happened at 0200 on a Sunday morning in January with an ambient temperature of about -20F. That wasn't fun.
    2013 Volkwagen Passat TDI, 2008 and 2010 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • Thanks. The bubbling stopped after the treatment. Do water pumps malfunction internally? No evidence on the outside.
  • xwesxxwesx Fairbanks, AlaskaPosts: 9,932
    Mine leaked slightly from a "weep hole" that was in the channel for the impeller shaft. That is a sign that the internal seal has gone bad. The belt pulley was spinning but the shaft sheared.
    2013 Volkwagen Passat TDI, 2008 and 2010 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • paisanpaisan Posts: 21,181
    The pump can definitely fail internally. I would look to the water pump or an air bubble in the system.

    When it's over heating on the gauge, is the radiator hot or cold? Is the Upper rad hose hot or cold?

    Subaru Guru and Track Instructor
  • Just ran it 2 miles the last leg up a hill and it got hot. Just under the top line (normal is under middle.) Radiator was kind of hot the same with the top rad hose. Didn't seem to match what would be scalding temp of the gauge. Which direction does the pump push the coolant? I can pull a hose and definitively know if the pump is defective. Heater was blowing cold so there is surely a circulation problem. How is air purged from the system? Thanks, appreciate the help.
  • paisanpaisan Posts: 21,181
    Ok if the rad and upper hose is only luke warm, my guess is you have an air bubble in the top of the engine and you aren't getting proper circulation.

    The proper method for "burbing" the system is to:

    1) When cold top off the coolant by removing the upper rad hose from the radiator use a funnel to back-fill the engine from the upper rad hose.

    2) Re-attach the upper rad hose and then fill the radiator through the radiator cap.

    3) Run the car at 2500-2700rpms until the needle moves to the normal position

    Subaru Guru and Track Instructor
  • Excellent! The burb worked. As this has been an ongoing problem I suspect that if it reoccurs, there is a head or head gasket issue. Upon checking the overflow I noticed a slight exhaust fume odor. I'm not sure if it was residual from the pre Blue Devil treatment or if it is still an issue. If the problem returns I can safely assume the above? That exhaust gases are creating the circ problem as well as superheating the coolant? Thanks again.
  • xwesxxwesx Fairbanks, AlaskaPosts: 9,932
    The gases likely aren't overheating the coolant, but they certainly can cause circulation problems. If you are getting gases in there, you might also see some combustion byproducts (tiny black flecks/spots/etc) begin to build up in the overflow bottle. Also, if you pop open the overflow bottle while it is running, you might also see occasional (or a steady stream) of bubbles coming from the overflow tube.
    2013 Volkwagen Passat TDI, 2008 and 2010 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • Actually did notice black flecks in the overflow along with the faint smell of exhaust fumes. It is the wifes car and it has only been about 5 miles so far since the burb but I get the feeling it was only a temporary fix. I've learned that this year (1997) is notorious for head gasket failure. Is it necessary to pull the motor to do this or can it be done in-chassis? The car is in otherwise mint shape but has 177,000k on it. Don't want to spend $1500.00 to have it done. Thanks.
  • paisanpaisan Posts: 21,181
    If it is the headgasket you need to pull the engine and it's going to be in the ballpark of 1500 to do it :(

    I would wait and see before jumping to conclusions on that though.

    Subaru Guru and Track Instructor
  • xwesxxwesx Fairbanks, AlaskaPosts: 9,932
    Charlie, this is the same symptoms I had on my 1996 Outback before replacing the head gaskets. I did mine at 192,000. I did not have any overheating issues as a result of the problem, but since it was our only "daily driver" at the time, I felt it prudent to schedule the repair rather than having to do it on an emergency basis.

    I have heard that you *can* do the repair with the engine in the car, but I do not recommend it! These engines are very easy to pull (cherry pickers can be rented from most local tool rental businesses for reasonable rates) and it is a breeze to work on them when not in the car. The process is fairly labor intensive (I estimate it took me about 18 hours total to do it), but well worth the effort. Total parts cost (I replaced my timing belt and pulleys at the same time, which was the majority of the cost) was ~$550 at the time.

    I did have a pictorial write-up for mine, but that web host has since shut down. I may have a copy of the page stored on my system if you would like me to send it to you just to give you an idea of the process and the work involved.
    2013 Volkwagen Passat TDI, 2008 and 2010 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • Thanks to everyone. I'm leaning towards a trade-in. Not really keen on doing the work or shelling out the dough. Appreciate the offer.
  • Thanks for all the overheating past posts. I am now using them to troubleshoot a unit in Paducah, KY from Baton Rouge, LA via phone. 288K service miles on it. Man up there replaced thermostat, improvement, but not resolved. Overnighted a radiator up there. Still overheating after a mile or so. He advised bottom hose cool, top is warm/hot. Hmmm, circulation not happening still. Can travel at lower speeds. 35/45mph. Not good for interstate.

    Now remember, fleet mentality here. Get it on road back to shop. He does not have towing available.

    Found one post about water pump shaft shearing off, not good news. Pump has 77K of service on it. Also aware of posts about exhaust leaking into cooling system and the purge hole on top of rad. So at this point, recommendation with ambient temps at 80 in morning and 90 plus daytime, pull thermostat totally. Then warm up and observe upper and lower hoses for circulation. If they warm up, then test drive and gradually load it down. Only try A/C if it manages to cool. If it holds, then get it back to shop and purchase OEM stat.

    Conversation with dealer also revealed that they use only Subaru coolant with a special sealant to prevent smaller head gasket leaks. So there goes the Wal-Mart coolant mentality on Subies.

    Will update later as this saga contiunes. A response to someone commenting about stats not fluctuating. You are correct when the ambient temps are high, but you will see them do it in colder temps. The time duration is shorter in newer/smaller/passenger models with radiators closely matched to engine size and not for carrying loads. Larger systems like trucks carrying no load you will see longer durations in colder weather. This is why many truckers block air flow off partly in colder weather.
  • xwesxxwesx Fairbanks, AlaskaPosts: 9,932
    If it is exhaust gas from a head gasket issue causing the problem that frequently, I would expect a user to be able to see bubbles forming in the radiator if the car is started (cold) with the cap off. Or, even seeing bubbles in the overflow tank if the cap is left on. I could with mine, even though I was not having overheat issues and the bubbles were infrequent. Another sign was that there was "combustion gunk" that coated the sides of the overflow bottle (black coating of tiny little flakes). I replaced the head gaskets at 192,000 miles; this was on a 1996 Legacy Outback.

    If it is a water pump failure, I would expect no circulation, but more consistency. I had a water pump also fail on mine (about 177K), and there were two brief instances prior to the full-blown failure where my temp gauge began climbing steadily, then suddenly dropped to normal and stayed constant. I am not sure what was happening on those two times, but they lasted less than a minute or so. A week later, the pump failed and that was that... no more circulation (although there were no other symptoms). It worked perfectly once I replaced the pump.

    If this is a repeatable scenario, I would lean toward exhaust gas causing an interruption in flow due to a failed head gasket.
    2013 Volkwagen Passat TDI, 2008 and 2010 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • I totally concur. Since I could not get confirming answers on the phone, I made the trip up there and condemned the engine! Interesting case.

    Found no bubbles in exhaust, found no gunk in overflow. Did find the upper rad hose collasped! Topped her coolant off and questioned carefully what has been done. Removed one end tank off the OEM rad. Examined it. Clean as a whistle. Replacement rad installed when I got there. ran her, warmed her up. Purred like a kitten. Top hose hotter than bottom. That made no sense because if I am correct, coolant flows from bottom to top. Out came a white tissue to the exhaust. It got damp, hmmm, I think I smell trouble. Allowed her to cool down. Sure enough coolant is down. Diagnosis, blown head gasket with severe overheating. Engine no longer suitable for open road service.

    Found OEM rad to be okay at 288K, water pump was fine, but they had tossed the thermostat so I could not evaluate. Failure occurred at 70 mph, so a lot of symptoms from a slow failure were not present. On the other hand, the shop that has the car right now, even their Subie man scratched his head on this one.

    Like I always tell people, above 200k, anything goes. Around 300K, things get real interesting. Nice thing, found an 98 engine in Billings, MT with 2600 miles on it for $1500 with $280 for shipping. Sweet if everything is as stated.

    I do intend to run the recommended OEM coolant, additive and distilled water in the cooling system from now on. Time will tell. Car has a manual driveline, so it should be good for another 200K.
  • hank48hank48 Posts: 3
    Let me know if you have any issues with the manual drivetrain, I sure do! Hank
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