WoodsWagon Posted December 1, 2006 Share Posted December 1, 2006 What makes the pistons so loose in the first gen 2.5's? The one I'm resealing knocked pretty bad when we did the quick runs to move it into the garage. All the bearings seem fine, no slack, but you can rock the pistons in their bores a lot. pushing on one side, then the other, good shift and click. I didn't have the time to pull the pistons and measure the skirts, but wow that's a lot of movement. Link to comment Share on other sites More sharing options...
johnceggleston Posted December 1, 2006 Share Posted December 1, 2006 What makes the pistons so loose in the first gen 2.5's? The one I'm resealing knocked pretty bad when we did the quick runs to move it into the garage. All the bearings seem fine, no slack, but you can rock the pistons in their bores a lot. pushing on one side, then the other, good shift and click. I didn't have the time to pull the pistons and measure the skirts, but wow that's a lot of movement. whsn they designed the 2.5 they were looking for more horsepower. one way they got it was to lighten the piston and/by shortening the skirts. this leads to piston slap. i don't know why some slap and some don't. but it's not a subaru only problem, gmc has it on some of their big engines. (too bad subaru didn't learn from them or vice versa) the solution is to replace the pistons, i think passenger side is most likley to slap. i think the pistons were redesigned , but i'm not sure. if under warranty and the customer complains long enough they will fix it. but some don't develope until the warranty is over. supposedly slap is not an indicator of imminant failure, but i'm not sure. i'll let you know in 100k miles. most time the the slap goes away after the piston heats up and expands, mine doesn't. it lessens, but it still slaps. Link to comment Share on other sites More sharing options...
WoodsWagon Posted December 18, 2006 Author Share Posted December 18, 2006 This slap is pretty bad. Sounds like a diesel when it's running. Does yours trip the knock sensor? Link to comment Share on other sites More sharing options...
johnceggleston Posted December 18, 2006 Share Posted December 18, 2006 not that i'm aware of. no codes. but i don't know how it may affect the timing or gas mix. i will say that around town all short hops, i get really crappy gas mileage, 18 - 19 maybe. the hiway is ok, 24- 25 mpg at 70 mph, but then it's running long enough forthe slap to deminish. i used to drive 2/3's hiway and average 25 mpg. now i'm 2/3's city and it stinks. john This slap is pretty bad. Sounds like a diesel when it's running. Does yours trip the knock sensor? Link to comment Share on other sites More sharing options...
nipper Posted December 18, 2006 Share Posted December 18, 2006 But thats typical 19 in city driving. Car weighs over 3000 lbs and has awd, for that its pretty good. nipper Link to comment Share on other sites More sharing options...
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