1998 Subaru Forester Logo
Posted on Feb 06, 2009
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Engine make Knocking noise when cold

I have a 2.0 petrol Subaru forester that makes a knocking / tapping sound when the engine starts. Once it has warmed up it stops making the noise..... Does anyone know if it's the start of a problem?

  • christoph33 Feb 06, 2009

    Thanks for the input. It has 115,000 km

  • carlo24 Mar 03, 2009

    i also have this problem, brought it to a mechanic they adjusted the valve clearance and changed the engine oil but still there is that knocking sound but not that loud anymore

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  • Posted on Nov 26, 2009
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I have the same problem on my 2.0L 2001 Legacy auto. It began about 1000 miles ago. It has now done 84k. From my online searches this is most probably 'piston slap', and is not serious. To save weight Subaru shaved down the skirts on the pistons. With normal engine wear the pistons will at some point rattle against the cylinders until the engine is heated up and the pistons expand. The rattling should go away after a few minutes. If it persists say 10-15 minutes, it may be another problem.

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  • Posted on Feb 06, 2009
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I could be one of 3 things, #1 lifter might loose prime when it sets for a while like overnight, #2 could be rocker a little loose witch is part of lifter that runs on a pushrod, and #3 could be a ristpin witch holds piston to connecting rod a little worn. None of thies are a real big thing unless they get louder or longer in duration. I don't know what kind of miles are on it but what you describe is usely associated with high millage. Just keep your ears open.

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  • Dorie Erickson
    Dorie Erickson Dec 01, 2013

    my 95 ford taurus knocks when started and keeps it up until car get warmed while driving. Is this teh catlytic converter?.

  • Dorie Erickson
    Dorie Erickson Dec 01, 2013

    noise is in front of the engine not in the engine. Code 421 is not in the manual. a Comment

  • Gary Alford
    Gary Alford Feb 26, 2014

    Had a few 3.0 taurus's and they never made a noise! even with high miles, a real bullet proof motor!

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I have a 2001 Subaru Forester. When the car is cold (not the engine); so in the winter months when I start the car there is a loud rattling/knocking in the engine area. Once the car heats up, it goes away....

Ever had your wedding band on during the winter outside and it wants to fall off ,same thing for cars metal expands and could cause some unwanted noise from heat shields and such thing is to find it and eliminate this sound 1 morning you must find this sound and where it is so you do not confuse that sound with an actual rattle inside the block so please find and fix this problem you will thank me later.
Thanks in advance please remember to rate and leave testimonial this is how we get our milestones on FixYa and please remember we are volunteers here we receive no payment and work jobs too so answers may not come as fast as you like please be patient with us. Thanks for using us the FixYa team.
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3. Personaly i've put "Restore" Engine Restorer & Lubricant in cars with more then 200 000 km and the results are amazing. But only "Restore". My Volvo is at close to 300 000 km, and it runs great. It's not a cleaning agent.

By experience if the knocking just started you can put an easy extra 100 000 km on the engine before a rebuilt. Quality Oil & let the engine warm up ( 3 mins ).


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