Question about 2003 Subaru Outback

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Subaru Outback - '03 boxer 2.5L engine sounds like a diesel

2003 Subaru Outback wagon w/ 2.5L 4 cylinder boxer engine sounds like a diesel all the time. Some sort of valve slap/tapping. Two dealers have told me that the boxer engines just makes that noise, but I have had an '02 Legacy wagon w/ a 1.5L four boxer and have an '07 Legacy sedan with a 2.5L four boxer engine, neither one of which makes/made that noise. Is there a cure for the noise?


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  • pmcintyre Feb 05, 2009

    It's -4 degrees at the moment, up from -16, so heavier oil won't be a solution. This happens year-round, summer and winter. I've run 10w-30 and 5w-40 in the engine with no difference. Dealers claim valves are properly adjusted, but I think something else must be off.

  • Anonymous Mar 01, 2009

    i own a 2003 2.5 outback w/ 50,000 miles and the engine just blew
    its had scheduled maintnence since weve owned w/ 13000 miles
    mechanic say theres no compression in left head. Does anyone have any ideas! warrenty expired last year is this a lemon law thing?

  • cbreinh Apr 09, 2009

    '03 2.5L subaru outback with 126k miles that also makes a knocking noise. dealership looked at it and said thats just a boxer.

  • Anonymous May 05, 2009

    05 Outback Wagon 2.5L load rapping noise 9sounds like a deisel) poor/cheap gasoline is NOT the problem. Does NOT stop when engine is warmed up. Sound is louder when car is idling.



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Heavier oil if you are not in a cold climate. but before you do that have the oil pressure checked. We used to use a can of STP every once in a while on a motor in a dodge we had... nothing wrong with it... was just noisy.


Posted on Feb 05, 2009


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