1999 Subaru Outbacl 2.5 LTR Overheated and Running Rough

mike120amike120a Member Posts: 9
edited September 2014 in Subaru
Ok, A little history report. I bought this car about a month ago. The previous guy said he overheated the car and it was blowing white smoke. He said he put in the thermostat backwards(car didn't start up). I bought the car for a good price knowing I would need to replace head gaskets, etc. I replaced the head gaskets/shaved the heads, and even had a compression test on the heads done once they were off(very expensive, i recommend buying the tool and doing it yourself before taking engine apart). I put everything back together and made sure the thermostat was facing the right way etc.

The car started up great and sounded very good. I let it idle for awhile and it stayed cold for about 5 or more minutes(i was worried). I shut the car off and turned it back on, this time it showed the temperature was starting to get warm. I was relieved thinking that at least the temp sensor is working and i let the car run for awhile. The car's temp gauge was in the middle and it was fine. Later on i took the car on a test run, it was still blowing white smoke but stopped when i wasn't giving it any gas. The car ran like a dream, it was very smooth and nice. After a few minutes driving at higher speeds it started to warm up even more and got up near the H(hot) mark. It was close to that for about 10-15 seconds before i was able to pull over and shut the car off. I waited for about 15 minutes and started the car(since i only had a few blocks to get back home) and the car was running rough and missing. Now the check engine light came on(it didn't come on until after it got hot and i turned the car back on).

I ended up pushing it back home after an attempt to get it home but it just ran rough so i pulled back over. I let it sit for about 30-45 minutes before starting it to see if it was still idling rough, and it was.

I'm gonna check the thermostat soon and also see if the water pump has been leaking. Do u think that by overheating for that time period would call the head gaskets to blow? Also there wasn't any hot air blowing when i turned the heat on. The upper radiator hose was blazing hot and the lower radiator hose(on the thermostat) was cold.

Any Ideas?

Any help is appreciated.

Thanks in advance


  • mike120amike120a Member Posts: 9
    quick update,

    the rough running i found was from a fuel injector not plugged in all the way(plugged it back in and runs good).

    It quit smoking the last 2 days i've started it and let it idle, etc.

    Also the upper radiator hose is hot but the lower radiator hose is cool.

    The heater blows cold air(i just replaced the thermostat with a subaru thermostat) I really hope it's not the heater core. :(

    The temperature gauge jumps from cold to the middle as soon as the radiator fans kick on.
  • xwesxxwesx Member Posts: 16,289
    It's probably the other way around..... the radiator fan kicks on as soon as the sensor reads appropriate temp.

    I still think your water pump is going/went out. Mine went from "works most of the time" with rare blips in temp that made me think "huh?" to nothing. I could nurse the car along the road at very low speeds without pegging the temp needle, but I had no heat inside the car (and it was -20F that night!). I limped to a friend's house, pulled it apart the next day and replaced the water pump, and no more problems.

    Do you have any coolant seepage out of the "weep hole" in the body of the water pump, just behind the pulley?
    2018 Subaru Crosstrek, 2014 Audi Q7 TDI, 2013 Subaru Forester, 1969 Chevrolet C20, 1969 Ford Econoline 100, 1976 Ford F250
  • mike120amike120a Member Posts: 9
    I am planning on checking this weekend to see if it's the waterpump. Because there is cold water in the radiator and hot water in the engine when it's running. So it's not circulating at all. I hope it's just the water pump. lol
  • bigfrank3bigfrank3 Member Posts: 426
    To me you have all the symptoms of a big air pocket. Sensors that are designed for temp reading in fluid don't read air temp very well. I have seen cars that are clearly overheating and the temp gauge reporting "normal" or "cold" because there was air around the sensor not fluid. Cold air from the heater is a big clue too.

    In the other thread wes suggested ramps to get the nose of the car up so the air can rise to the radiator cap, and this is excellent advice. A big hill works great too. The way cooling systems are designed today it is almost impossible to get all the air out with the car level.
  • mike120amike120a Member Posts: 9
    Just wanted to update, the car is good now. It was just an air pocket(several actually). I did replace the thermostat though since it had an aftermarket one to begin with. Thanks so much for the help!
  • subarujoe73subarujoe73 Member Posts: 3
    was wondering how high the subaru needs to be when lifted up?! I am having the same problem with my 99 legacy outback. Tried to bleed out all of the air but it would just sit at the top of the radiator opening and the car started to heat up after reaching normal operating temp. Hoses are hot up top and cold on the bottom. Doesn't look like I am getting any circulation either. Plz help. :sick:
  • mike120amike120a Member Posts: 9
    I didn't lift my car up at all when i bled it... If i remember right there is a little valve on the passengers side of the radiator(top) u need to open up and leave open while your car is running. Hope this helps.
  • paisanpaisan Member Posts: 21,181
    Guys the proper way to bleed the subarus is to back-fill the upper rad hose into the engine, then put the hose back onto the rad. Fill the rad up.

    The important part is to run the car at 2500-3000rpms until the needs comes up to normal operating temps with the heat running. This ensures that it circulated throughout the sytem and all the air comes out.

    Subaru Guru and Track Instructor
  • subarujoe73subarujoe73 Member Posts: 3
    Thank you guys, I will try this seeing as how it overheated going to Kingman AZ again =\ Will post my results after doing this. Thanks again!
  • subarujoe73subarujoe73 Member Posts: 3
    Ok, so what is it if the overflow fills up and doesn't drain back into the radiator??
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