Fireindc's attempt to build a decent miata. (the search for more torque). - Page 26 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 12-21-2013, 12:30 AM   #501
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Double posting in my own thread. Anyways that's my fail so far in subaru land.
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Fireindc's attempt to build a decent miata.  (the search for more torque).-jto3d29.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-ohlu8gd.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-t0lmpve.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-ixsxxdq.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-k6w6pc4.jpg  

Fireindc's attempt to build a decent miata.  (the search for more torque).-4rbmlhl.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-ionf3mg.jpg  
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Old 12-21-2013, 01:49 AM   #502
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That doesn't look like a newer 2.5, did you run the vin?
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Old 12-21-2013, 02:04 AM   #503
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That doesn't look like a newer 2.5, did you run the vin?
It was, at least judging from the accessories. It had a drive by wire throttle body and a much beefier intake manifold on it, but i swapped everything over to what came on the foz. (some sensors, crank gear with different triggers, and the dr. side cam gear because it was different.).
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Old 12-21-2013, 12:47 PM   #504
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Most people do leakdown testing at TDC. This assumes that cylinder condition on the entire stroke is the same as cylinder condition at TDC -- which is often an incorrect assumption.

Best to do both leakdown and compression testing. During a compression test, you monitor the pressure built by traversing the entire stroke.

$$0.02.
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Old 12-21-2013, 12:58 PM   #505
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Most people do leakdown testing at TDC. This assumes that cylinder condition on the entire stroke is the same as cylinder condition at TDC -- which is often an incorrect assumption.

Best to do both leakdown and compression testing. During a compression test, you monitor the pressure built by traversing the entire stroke.

$$0.02.
Thanks for the insight. And for the record, i did do both leakdown and compression tests.

Leakdown resulted in good even readings, less than 15% across the board.

Compression test resulted in:

drivers side bank = 130psi (both within 5 psi of each other.
pass side bank = 160psi (both within 5 psi of each other)

This is part of why i suspected a HG initially, because the drop in PSI on the entire bank made me suspicious. Not so sure anymore! We shall see, off to go snowboard for now though.
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Old 12-21-2013, 03:12 PM   #506
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Originally Posted by Fireindc View Post
Leakdown resulted in good even readings, less than 15% across the board.

Compression test resulted in:

drivers side bank = 130psi (both within 5 psi of each other.
pass side bank = 160psi (both within 5 psi of each other)

This is part of why i suspected a HG initially, because the drop in PSI on the entire bank made me suspicious. Not so sure anymore!
This is a classic indication that something is up with the cylinders/rings. The leakdown result shows that the head/head gasket is fundamentally sound and the rings are holding compression at TDC. The compression result shows that something is wrong with the cylinders/rings on the passenger side bank as the entire stroke is traversed -- and whatever it is affects both cylinders -- which is kind of wierd -- maybe the block is cracked between the two? In for teardown pics!

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We shall see, off to go snowboard for now though.
Damn you and your snow and your mountains. Jealous.
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Old 12-26-2013, 08:34 PM   #507
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Okay guys, sorry.. no pictures. But bear with me here, this is the synopsis.

So far, even just pulling the valve covers this is internally the cleanest motor I've ever disassembled. I got the heads off and they are in great condition, pistons look good from the top with minimal carbon, cylinders don't have a scratch on any of them and the hone looks brand new.

Also, the head-gaskets are fine. This is all good news, but it leaves me wondering WTF the problem is. I guess the next step is going to be to pull the pistons (which you have to do before splitting the cases anyways) and look further. I know the motor sat, so maybe I'm dealing with a stuck oil control ring.

I'm thinking about re-ringing it and leaving the bottom end. This motor clearly is around the 60k claimed miles, and I'd really like to slap it back together and run it seeing how nice it is internally. I'll get pictures tomorrow!
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Old 12-26-2013, 09:07 PM   #508
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When do we get back to our regular scheduled programming?
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Old 12-26-2013, 09:23 PM   #509
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When do we get back to our regular scheduled programming?
Plas Juan.
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Old 12-26-2013, 09:25 PM   #510
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When do we get back to our regular scheduled programming?
Once I get this subaru out of the garage, so hopefully within the next month.
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Old 12-26-2013, 09:31 PM   #511
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Sounds good. and don't split the halves unless you absolutely positively have to.
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Old 12-26-2013, 09:42 PM   #512
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Sounds good. and don't split the halves unless you absolutely positively have to.
This was my thought, there should be no need to split the cases for a quick re-ring since the bores look so good.

Plus i'd like to get this thing up and running asap so I can focus on the BP.
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Old 12-27-2013, 05:42 PM   #513
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True no point spending more money on it then you have to. Once you find the issue slap it back together and get that waste gate on your Miata so I can see what my car will be doing in a few months!
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Old 12-27-2013, 05:58 PM   #514
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he already found the issue
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Old 12-27-2013, 06:09 PM   #515
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LOL, yeah man. I'm completely ashamed but I'll own up to it. I'm a n00baru.

So, I basically hooked up the subaru PCV system backwards. I hooked up the valve cover breather directly to the intake manifold. SO i believe it was acting like a straw, sucking tons of oil from the valve covers and dumping it in the intake.

This explains why the airbox itself was clean, yet there was oil literally pooling on the intake valves.

Apparently this isn't a miata. Sideways valve covers, wtf?!

Last edited by Fireindc; 12-27-2013 at 06:23 PM.
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Old 12-27-2013, 06:19 PM   #516
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Please notice the "fail" behind the coilpack there running to the pas side head.

Did not figure this out until i pulled the motor apart to find pristine internals, THEN of course i second guess my pcv routing.
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Old 12-27-2013, 06:23 PM   #517
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Checked this thread for the first time in a week. See a subaru motor.

I'm so confused.
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Old 12-27-2013, 06:27 PM   #518
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Wait... there's a different time to find out stupid mistakes other than when you have the entire car torn totally apart?
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Old 12-27-2013, 06:33 PM   #519
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I just got lucky...fucked..to be able to find them that way!
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Old 12-27-2013, 06:36 PM   #520
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Wait... there's a different time to find out stupid mistakes other than when you have the entire car torn totally apart?
I guess it's never a bad time to do headgaskets on a subaru
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