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Burnt exhaust valve (again) - good excuse for new shortblock!


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So for the second time in 2 years, I burnt an exhaust valve. The first time, it was #2, and this time it was #4.

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I debated whether to just replace the valves, machine the heads, and call it a day, but after talking with a few knowledgeable Subaru locals, they suspected I might be getting excessive blow-by, and thus...hello new IAG Stage 1.5 shortblock!

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The build stalled out for awhile while I waited for IAG to build me a block, then stalled out again while I waited for a bunch of little parts like O-rings and gaskets to transfer all the stuff from the old block to the new one.

 

Now we're at the stage of bolting everything back together, and came across an interesting discovery: the camshafts - it looks like the camshafts have been friction welded:

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...but the markings seem to indicate that they're stock cams?

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So, over the weekend we got all the accessories bolted on and dropped the engine back into the car.

 

The only thing I'm a little (or a lot) nervous about is when we were doing the timing belt install, and my friend was holding the driver side intake cam in the aligned position while I rotated the exhaust cam...but I accidentally rotated it the wrong (clockwise) way - not very far, only about 20-30 degrees from where it was naturally sitting, when we heard that spring releasing noise, only it sounded a bit different. I'm just worried we way have smacked the valves against each other and damaged them. The intake valves look fine from a visual inspection from the manifold side, but it's harder to see the exhaust valves. Short of a proper borescope inspection (or tearing down the heads again), I'm not sure what to do other than keep my fingers crossed when we go to first turn it over. :eek:

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PM "m sprank" Mike knows these cars really well. He used to have a repair shop.

 

Hint, you can buy parts from him too.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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  • 3 weeks later...

So I'm a little late with this update, but the engine is back in and...

 

She runs! Fired up the first time with no issues and no leaks (although I did get a TGV stuck open code that I haven't been able to get rid of, but I'm not too worried about it). So relieved that there were no issues with the valves or our timing belt replacement job.

 

Now I have about 1,000 miles of break-in to get through before I can get it tuned properly.

 

Also, after missing out on a killer local deal for a Quaife front LSD, I picked up a very lightly used STi front LSD which I'm hoping to get installed in a couple of weeks.

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