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Outback overheating
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.
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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.
When it's over heating on the gauge, is the radiator hot or cold? Is the Upper rad hose hot or cold?
-mike
Subaru Guru and Track Instructor
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
-mike
Subaru Guru and Track Instructor
I would wait and see before jumping to conclusions on that though.
-mike
Subaru Guru and Track Instructor
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.
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.
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.
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.