Engine knock. Is it Piston Slap? - Subaru Outback - Subaru Outback Forums
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post #1 of 11 (permalink) Old 01-06-2009, 02:53 PM Thread Starter
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Engine knock. Is it Piston Slap?

I bought an 03 2.5 outback about 4 weeks ago. I noticed a little engine noise when i test drove it but not much. Once i got to driving it everyday the noise is straight annoying. I did some research and found people reffering to piston slap. This noise sounds like a tap or a knock noise. I replaced the timing belt tensioner when i did the belt week one. I have put almost 6k on this car since i bought it and it seems to have the correct power for the size of the car. (no loss of power) the noise is very loud when the car is cold and calms down some after driving for an 30 min. or so. I drove to Florida last week and it didnt seem to be as loud during the trip. I even tried some heavier oil to see if it would quiet. I have heard one other OBW with this same noise. could it just be piston slap? should i rebuild the motor for that or just leave it be and live with the noise. Any thoughts would be appreciated.

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post #2 of 11 (permalink) Old 01-06-2009, 04:23 PM
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Re: Engine knock. Is it Piston Slap?

Quote:
Originally posted by itstowtime
I bought an 03 2.5 outback about 4 weeks ago. I noticed a little engine noise when i test drove it but not much. Once i got to driving it everyday the noise is straight annoying. I did some research and found people reffering to piston slap. This noise sounds like a tap or a knock noise. I replaced the timing belt tensioner when i did the belt week one. I have put almost 6k on this car since i bought it and it seems to have the correct power for the size of the car. (no loss of power) the noise is very loud when the car is cold and calms down some after driving for an 30 min. or so. I drove to Florida last week and it didnt seem to be as loud during the trip. I even tried some heavier oil to see if it would quiet. I have heard one other OBW with this same noise. could it just be piston slap? should i rebuild the motor for that or just leave it be and live with the noise. Any thoughts would be appreciated.
I'm not really sure that it would be piston slap cause that piston slap usually goes away as soon as the motor reaches operating temperatures. I have piston slap when the motor is cold and it goes away after about 5 min.

That's all I can really comment on since I'm not too experienced with knock.

Hope everything works out ok though.

Andre

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post #3 of 11 (permalink) Old 01-06-2009, 05:05 PM
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Sounds like piston slap to me .My 02 had it and the noise never went away .t would get considerable quieter once it warmed up . I have to say that in the 90 k miles I drove my car it never burned a drop of oil. I also had my oil anylased every other oil change and it always came back good no high metal reading.
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post #4 of 11 (permalink) Old 01-06-2009, 06:44 PM
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http://www.ultimatesubaru.org/forum/...ht=piston+slap

Piston slap goes away though after the car runs a minute or two. Sounds are very hard to diagnose over the net, you may have to get a trained ear to listen to it.

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post #5 of 11 (permalink) Old 01-06-2009, 07:42 PM
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checkout a few videos on youtube for piston slap...you'll learn relatively quickly what it sounds like.
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post #6 of 11 (permalink) Old 01-07-2009, 09:34 AM
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Quote:
Originally posted by nipper
http://www.ultimatesubaru.org/forum/...ht=piston+slap

Piston slap goes away though after the car runs a minute or two. Sounds are very hard to diagnose over the net, you may have to get a trained ear to listen to it.

nipper
So after reading your post on this link that you added, what oil do you use?

I use 10w-30 but I've wanted to try 5w-30. The only thing is that I'm afraid that the engine will leak oil since it's thinner.

Your take?

Andre

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post #7 of 11 (permalink) Old 01-07-2009, 10:53 AM
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Clackity-clackity-clackity...

Mine does it too. The colder it gets, the louder it is. I've been told it's the valves. Maybe when I get a valve adjustment at 105k miles it will go away...
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post #8 of 11 (permalink) Old 01-07-2009, 11:48 AM
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Quote:
Originally posted by 8kGoodENuff


So after reading your post on this link that you added, what oil do you use?

I use 10w-30 but I've wanted to try 5w-30. The only thing is that I'm afraid that the engine will leak oil since it's thinner.

Your take?

Andre
I have a 97 but I dont have piston slap. Blu got a rebuilt sooby engine 3 years ago, so he got the updated pistons that correct this problem.

If an engine is going to leak oil, its going to leak oil, if its not, its not. You dont ssya how many miles are on the car, Piston slap may be more detrimental then the annoyance of an oil leak. At 105,000 miles your due for a timing belt, and we also recomend replacing the oil seals (water pump and re-seal the oil pump) all at the same time, since these will all leak eventually.


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post #9 of 11 (permalink) Old 01-07-2009, 12:06 PM Thread Starter
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Sorry about not putting the miles. It has 111,000 on it now. I did the timing belt, tensioner, waterpump cam seals about 3 weeks ago or 4k ago. I am not worried about any oil leaks just the noise. I payed closer attention to the engine noise on the way home last night. It gets alot quieter after the car warms up. I still hear some noise but only if i am outside of the car listening for it.

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post #10 of 11 (permalink) Old 01-07-2009, 12:52 PM
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Quote:
Originally posted by itstowtime
Sorry about not putting the miles. It has 111,000 on it now. I did the timing belt, tensioner, waterpump cam seals about 3 weeks ago or 4k ago. I am not worried about any oil leaks just the noise. I payed closer attention to the engine noise on the way home last night. It gets alot quieter after the car warms up. I still hear some noise but only if i am outside of the car listening for it.
Then no worries about oil leaks. Swicth to synthetic oil and use the same grade like in the post.

see what happens.

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