Question about solving piston slap.
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Question about solving piston slap.
My wife's 99 Outback (ej25d, 105k mi) has more piston slap than I can tolerate so I intend to replace all 4 pistons. Do you guys recommend using new OE pistons or something from the aftermarket? When I asked some questions at the dealer they said that Subaru sells replacement pistons that are a couple of thousandths larger in diameter that solve the problem. Thoughts?
Todd
2002 Legacy GT Wagon 2.5/5mt
1999 Legacy Outback Limited Wagon 2.5/4eat(wife)
1998 Forester S 2.5/4eat
1972 Buick Electra Limited 455/TH400
1988 Jeep Grand Wagoneer 360/TF727
2002 Legacy GT Wagon 2.5/5mt
1999 Legacy Outback Limited Wagon 2.5/4eat(wife)
1998 Forester S 2.5/4eat
1972 Buick Electra Limited 455/TH400
1988 Jeep Grand Wagoneer 360/TF727
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- Third Gear
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I wouldn't do it at all. If it's just piston slap, your motor will more than likely live a long (albeit a bit noisy) life as it is. If you throw different pistons in without boring & honing the cylinders, there's absolutely no guarantee the pistons will fit correctly, nor can you be sure the cylinders are perfectly round and straight.
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Not to mention all the other crap that can be screwed up in the process - unless you want to go ahead and be thorough the whole way,which will cost too much to justify.
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Also (someone correct me if i'm wrong here) I believe part of the reason those engines get piston slap is that they don't have skirted pistons. Replacing the pistons will quiet it down....for a while. So far I haven't found any aftermarket pistons for that engine. I have found that supposedly Wiseco makes performance lower and higher compression pistons for the ej25 which are supposed to be skirted however the kit for pistons alone is upwards of $700.
90 Legacy L AWD 5mt
Formerly of the USMB but moved from an RX to a Legacy
Formerly of the USMB but moved from an RX to a Legacy
If you replace the pistons....
Your EJ25 Phase I is about due for its head gaskets too.
TD
Your EJ25 Phase I is about due for its head gaskets too.
TD
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Traditionally the dreded 2.5 piston slap happens on cylinder number 4, sometimes number 2. Now I'm not sure about the phase I motors but I do know that, as long as the bore is ok, subaru offers 0.0002" larger pistons that are supposed to cure this problem. All you need to know is what pistons you already have (A's and or B's) No boring or honing required (or so subaru says). So if your not wanting to do a whole rebuild I'd look into this and maby slap some pistons in your noisy cylinders.
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Good info, Subytech, thanks. How do I find out what pistons I already have and what's up with the A and B pistons anyway? What differentiates A from B?
Todd
2002 Legacy GT Wagon 2.5/5mt
1999 Legacy Outback Limited Wagon 2.5/4eat(wife)
1998 Forester S 2.5/4eat
1972 Buick Electra Limited 455/TH400
1988 Jeep Grand Wagoneer 360/TF727
2002 Legacy GT Wagon 2.5/5mt
1999 Legacy Outback Limited Wagon 2.5/4eat(wife)
1998 Forester S 2.5/4eat
1972 Buick Electra Limited 455/TH400
1988 Jeep Grand Wagoneer 360/TF727
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- In Neutral
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Yeah there are slightly different sized stock pistons, A, B, & C.
The block will be stamped with the size pistons it was put together with.
The block will be stamped with the size pistons it was put together with.
Josh
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
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1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
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Re:
Where might one find this stamping?Legacy777 wrote:Yeah there are slightly different sized stock pistons, A, B, & C.
The block will be stamped with the size pistons it was put together with.
subytech: how does one go about ordering the larger pistons?
Thanks guys.
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Re: Question about solving piston slap.
It's on the top of the block halves, right where they come together under the alternator. There will be a machined section and if you look closely, it will have the letters there.
You would need to order them from Subaru. Honestly.....if you're tearing down the motor to put in larger pistons, the rings will likely need to be replaced, which really means the bore needs to be rehoned so the rings seat.
At that point, you may want to look at buying a used or new short block....or rebuild the motor. However if it's a daily driver, I'd try and find a used motor.
You would need to order them from Subaru. Honestly.....if you're tearing down the motor to put in larger pistons, the rings will likely need to be replaced, which really means the bore needs to be rehoned so the rings seat.
At that point, you may want to look at buying a used or new short block....or rebuild the motor. However if it's a daily driver, I'd try and find a used motor.
Josh
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
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Re: Question about solving piston slap.
Found it, thanks.
Block is already torn down and rings were in the plan anyway. Anyone have access to a parts catalog w/ part numbers for the oversized pistons?
Block is already torn down and rings were in the plan anyway. Anyone have access to a parts catalog w/ part numbers for the oversized pistons?
93 legacy wagon L, 22T swapped (TW imitator) now with five forward speeds. (Gone, but never forgotten)
johndrivesabox wrote: Rally, my kyboard is brok, his has nohing o do wih h liquor.
Originalcyn wrote:Apparently everyone hates Gabe.
Re: Question about solving piston slap.
Email or PM your VIN, and I'll look them up on the electronic parts catalog I have.
Josh
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
Re: Question about solving piston slap.
this would kinda be bad if the factory installed the "c" pistons in your engine already due to their AKA tolerance in the factory....if they put largest in then, then what, find some "d" pistons... or sol.rolleyes
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91crx si 165k
91 Civic RT4WD manual trans 168k
91crx Si 40.5k
85 BRAT Gl 140
97 SVX 74k
Re: Question about solving piston slap.
Pretty sure there's only A, B, & C size pistons. If you need larger, you would need to have the engine over bored.
Josh
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
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Re: Question about solving piston slap.
A, B and C for our motors (2.2), and A or B for the Phase 1 2.5s, IIRC.
For the 2.5, A pistons are 3.9167 to 3.9171, while the B pistons are 3.9163 to 3.9167
For the 2.5, A pistons are 3.9167 to 3.9171, while the B pistons are 3.9163 to 3.9167
Disclaimer: If anything I post is inaccurate, please correct me. I do not wish to add to the misinformation floating around on the internet.
That being said, everything I post is accurate to the best of my knowledge.
Rio Red '91 Legacy SS
That being said, everything I post is accurate to the best of my knowledge.
Rio Red '91 Legacy SS