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Old 01-21-2019, 07:04 PM   #1
Metzenw
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Join Date: Mar 2013
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Location: Arlington, WA
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96 Impreza Coupe
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Default EJ20G Compression Test

I bought a 96 Impreza a few months ago with an EJ20G swap.

I got the car running well and bought everything for a Robtune. (Injectors, EBC, Coil Conversion.. ETC.)

So found out the engine couldn't hold the extra boost and lost number 4 cylinder.

Engine ran amazing before.

I did a compression test and i get Zero. Nothing.
I checked number 2 next to it and i get 120 PSI.

I did a leakdown test and I get better then 10% leakage.

Any idea how you can get Zero compression and yet pass a leakdown test with flying colors?

I hear a little air coming out the Oil fill, but nothing out of the Coolant, Intake or Exhaust.

Could I have a broken valve spring? and the pressure in the cylinder from the leakdown is keeping the valve close making it show good?

Either way the engine has to come out, cause I'm not pulling a head in the car.

I get this post is kind of redundant as I'll get the problem solved. I just figured i'd share this really weird situation.
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Old 01-22-2019, 03:17 PM   #2
dfj240
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I've seen that on a couple engines before. Both times it was valve related.

As you stated, you'll need to pull the head out and have a good look around, but my instinct would be that your bottom end is fine, and you may need a new valve or two and accompaniments. Seems that you're on the right path. Keep heading that way and let us know what you find.
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Old 01-23-2019, 12:40 PM   #3
Metzenw
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Well, found the problem. Destroyed the head. I'm currently looking into a set of K heads.
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Old 01-23-2019, 01:01 PM   #4
Charlie-III
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Silver Sleeper BK, 5MT

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Quote:
Originally Posted by Metzenw View Post


Well, found the problem. Destroyed the head. I'm currently looking into a set of K heads.
Ouch.........

That would do it, not a common issue on almost ANY engine, but yes, that would do it.
Good luck on the repairs. Glad it didn't wipe out more than we know of.....
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Old 01-23-2019, 04:48 PM   #5
dfj240
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I see no problem here... You just got the rare production, half-slanted camshaft model.

Seriously though, that's pretty wild. Good luck on the K head search. Might start looking into some other frankenstein head options as well. 205 heads or STI heads possibly?

Anyway, good luck.
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Old 02-09-2019, 12:52 PM   #6
Metzenw
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Well, got my car running last night.
A friend of mine had a set of K heads. I adjusted the valve lash on the heads. Shim Under Bucket. Used a surface grinder to adjust the thickness.

The engine turns out has Cosworth pistons from an EJ205 installed. Unlike the EJ20G Pistons which are said to protrude above the block deck by .020ish" the EJ205's sit about .005" below. So I reassembled the engine with EJ205 headgaskets. This brought the heads in closer and the EJ20G manifold wouldn't bolt up. So I drilled the holes in the manifold out by .020" from 9mm (.354") to .375 to get the manifold to line up.

The Timing belt tensioner is Almost at the max stroke, and the cam timing didn't line up perfectly. But the engine fired right up.

Everything runs great, has more lower end power then the G heads. I threw a Tomei Equal length manifold on. Really changes the exhaust. When the snow clears I'll do a video of the exhaust sound between my 05 WRX and this car. Which both have the exact same exhaust.

This will be my last plunge with Phase 1, stuff is getting too hard to source. Phase 2 stuff is Everywhere.
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