Rod knock/piston slap. - Subaru WRX Forum
 
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post #1 of 15 Old 03-20-2012, 10:55 PM Thread Starter
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Rod knock/piston slap.

Hey everyone,

I have an '05 :92x:. To start, this is what my engine sounds like. Saab 92x aero rod knock/ piston slap (WRX EJ20) - YouTube

I have been shopping mechanics in my area they all believe its rod knock/ or a spun baring but after that i have been getting some mixed messages.

I will obviously need to rebuild or get a brand new block. Which would be best for this? and what else should i get done while they are in there?

The subietech i spoke with suggested I could rebuild with a 2.2 stroker kit along with Valve/head job, a master gasket set, hot tank the manifold, intercooler and oil pan, New 12mm sti oil pump or rebuild mine, and a New oil cooler. And maybe a new turbo too

Does this all sound right. I know its going to be an expensive fix, but i want to get it right while they are in there.

Please help!

Thanks
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post #2 of 15 Old 03-20-2012, 11:26 PM
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If you put any rpms to it...does the knock stay consistant with the rpms? If yes...you have a spun bearing/rod knock.

Secondly...rod knock and piston slap are two different things for explanations sake. Piston slap is your piston slapping the cylinder wall and most forged pistons will do this. Now...assuming you're on a OEM engine. You will not have piston slap normally. Now rod knock normally happens...when your bearing inside of the rod that is connected to crankshaft is broken or loose (also known as a spun bearing). Causing your rod to flap around violently instead of staying connected tightly to the crankshaft. Now I know what you're thinking. Yes, when this happens your pistons will be slapping the cylinder walls also.

From when my engine spun one bearing severely and a second one was on its way out. It pretty much sounded like your car and the noise was consistant with the rpms. My spun bearings were from a abnormal occurance and I'd rather not take this topic off track. But, I'd say that what the subietech told you is pretty much right.

I got a lot of new stuff and upgraded when I was in there (again). A lot of what I got...you won't need. But, I will say this is what you will definitely need:
1) New Short Block
2) Tank the heads and see if they're damaged. If not, then you can leave them stock. IF damaged then you will either need new valves/head job or will be fixing whatever is broken.
3) You will need a complete new oil system. Oil Pump, Oil pan, Oil cooler (if you drive a auto), Oil filter assembly, and can't forget a new Oil Filter. With new oil...of course. If they can rebuild your pump...then that's up to you. You just want to make sure no shards of the bearings are in your oil system or you risk damaging the new engine and turbo.
4) See if they can send the turbo out to get inspected. Blouch Turbo inspected mine and fixed the damaged Intake side. (I got a cheap upgrade while Blouch was fixing it. The turbo got upgrade to a custom Dom 3). The last option is more expensive and its assuming the bearing shards damaged the turbo and just get a new turbo.

The rest of the 2.2 stroker kit and upgraded valves/heads and intercooler would just be a upgrade. Even if you did that...you'd still need a tune for the new engine/compression. If you decide to upgrade the turbo. Guess what? You will need larger fuel injectors and a high flowing fuel pump as well.

So, you can see what your options are. Repair it to stock, Repair it to 2.2 engine (needs a professional tune), or Repair it to 2.2 engine with larger turbo, intercooler, and fuel system upgrades (needs a professional tune).

Let me just set the record straight...the needs a professional tune is not a option. If the subietech is from a dealership/mechanic at ma and paps car shop...then I'm not to sure I'd even consider running the engine until you get it to a professional tune shop. You'd need a limp map from the tuner to drive it from said dealership/mechanic shop to the professional tuner's. Is this complicated enough for you? LOL

Again, reparing the car to stock requires no tune. So, you have some options to decide from.

Kirt
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"When in doubt...flat out" - Colin McRae
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post #3 of 15 Old 03-20-2012, 11:42 PM Thread Starter
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That is very helpful. i appreciate it. i understand what you are saying about the tune. and i hadn't even thought about it. I am on a budget and that is hope and a dream.

thanks again.
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post #4 of 15 Old 03-20-2012, 11:45 PM
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I editted my post after I read it back two/three times to make sure it wasn't too confusing. Not a problem man...I unfortunately had to experience this same situation last june. Its not fun one bit.

Kirt
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post #5 of 15 Old 03-21-2012, 12:18 AM Thread Starter
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Yeah its a rough one. It is my first car that is MINE. and i only got it back in January. So, its killing me that i need to drop so much money so soon that aren't upgrades for fun.
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post #6 of 15 Old 03-21-2012, 09:23 PM
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Why'd you just get it back in January? It makes it worse when you feel responsible for the rod knock/spun bearing.

Kirt
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post #7 of 15 Old 03-23-2012, 02:45 PM Thread Starter
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?I finally found one in good condition, for the right price.
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post #8 of 15 Old 03-23-2012, 09:55 PM
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Well, do you care to ellaborate on what you found? LOL. I'm guessing a used engine?

Kirt
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post #9 of 15 Old 03-23-2012, 10:31 PM
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Nah kirt, I think he's saying he just got the saabie back in January, as his first car. First one that he/himself payed for himself, with his own cash.

To the OP, let us know what you decide to do.
This could turn into an interesting build thread.....GL!

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post #10 of 15 Old 03-24-2012, 09:58 PM
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Gotcha....I wasn't reading it the right way.

Kirt
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post #11 of 15 Old 04-16-2012, 07:16 PM Thread Starter
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Hey guys,

Sorry for the delay getting back on here.

So this is what I did:
I went to Subie Specialties in Monrovia, CA. Good guys. Honest and conservative, not looking to do anything that is unnecessary. The SubieTech i talked to kept wanting to see how much he could get me to spend on upgrades and things like that.

New EJ20 block (Inquired about 2.5 but to expensive)
New timing belts and thermostat; didn't need a water pump because my was pretty new.
New radiator - aluminium core.
New hoses and other little things that needed replacement from age, wear and tear, known future problem areas.
New oil pan (to avoid any future issues from the metal shavings/ pieces that my have contaminated the system)
Heads pressure tested and cleaned ( I decided not to have them ported polished and matched b/c i would have had to do that independently)
Valves inspected and rebuilt where necessary.

I had the mechanic put everything on the car back to zero (diffs, transmission etc), essentially reseting my maintenance schedule.

I didn't need, but had inspected - Turbo was in good shape(Thank God), fly wheel and clutch didn't need any work.

I think thats about it.. Any questions?
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post #12 of 15 Old 04-16-2012, 08:55 PM
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Originally Posted by BFJ_92x View Post
I went to Subie Specialties in Monrovia, CA. Good guys. Honest and conservative, not looking to do anything that is unnecessary. The SubieTech i talked to kept wanting to see how much he could get me to spend on upgrades and things like that.

New EJ20 block (Inquired about 2.5 but to expensive)
New radiator - aluminium core.
New oil pan (to avoid any future issues from the metal shavings/ pieces that my have contaminated the system)

-2.5 block is $200 more than 2.0 block.
-Why do you need a radiator?
-You don't need a new oil pan, you might need a new pump.
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post #13 of 15 Old 04-16-2012, 09:52 PM Thread Starter
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Yes the 2.5 is only a little more by itself, but its not a straight change over. Off the top of my head, you need a bigger fuel pump, high capacity fuel injectors, same with the water pump.

I decided to do the radiator because the mechanic told me that around 100-120k they have issues. so i decided to get out ahead of the issue.

And the oil pan was not necessary, but if his experience they are hard to clean and if you don't get all the contaminants, it can lead to the same or other significant problems.
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post #14 of 15 Old 04-17-2012, 06:55 AM
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Good call on the radiator... Subie puts in some garbage from the factory.

Paul
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post #15 of 15 Old 04-17-2012, 11:20 PM
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So, its back up and running?

Kirt
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