Looking inside

Update by Alan Cesar to the Subaru Impreza WRX project car
Mar 15, 2013

The shop manual calls for a special puller to remove the piston pins through the side of the block before removing the pistons and separating the case. We didn't have that tool handy, so we cut the bottom section from a plastic coat hanger and drove the pins out from the other side.
After removing all the other fiddly bits, we split the case—held together by long, long bolts—and looked at the bearings. The mains all looked more or less like this.
We spun three rod bearings—all except No. 4—but No. 2 showed signs of being hammered by detonation. The force worked the bearing like a blacksmith, causing it to squeeze out the sides of the connecting rod journal
We tried to inspect the crank, but our measurements were too close to the limits for us to be comfortable reusing the crank as-is. We took it to a machine shop to properly inspect and, if necessary, regrind the whole mess.

Since our last update, we’ve completely removed the cylinder heads, coolant crossover pipe and all the other accessories on our boxer engine’s block. We were itching to see what had actually happened to the bearings that we saw lots of pieces of inside the oil pan.

We found three spun rod bearings and some chipping of the main bearings. One of the rod bearings showed signs of detonation hammering, with the bearing material having worked its way out of the journal area. The crank’s rod journals are a bit scored and also show some bearing material transfer.

We pulled out the tools in our tool chest to see if we could determine if the crank was salvageable, but this is a job for which we’re not properly equipped either in skills or in tools. This is the kind of craftsmanship you want to entrust to someone who can afford a quality tool set and has done it enough times to really be able to tell us what’s going on. To make sure the crank is OK, we’re taking it—and the block and heads—to a machine shop that has all the right tools and expertise to really check everything out.

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View comments on the GRM forums
JeffHarbert GRM+ Memberand Reader
3/15/13 10:01 a.m.

Wow. That's not just a little detonation hammering, either. I hope the crank is salvageable. I'd also suspect some oil starvation.

Alan Cesar
Alan Cesar Dork
3/15/13 10:07 a.m.

There was oil starvation for sure.

Ransom GRM+ Memberand PowerDork
3/15/13 10:24 a.m.

Holy carp. Before I read the detonation hammering explanation, I thought that was a very badly worn thrust surface...

Jerry From LA
Jerry From LA Dork
3/15/13 11:18 a.m.

Here's what I learned today: 1. These engines look really interesting to build and I'd love to try one. 2. Do not buy cheap car from fellow board member. :)

jmr302 New Reader
3/15/13 11:45 p.m.

Alan, be careful. If you grind the crank down a size it may not have the original nitriding anymore and won't be as durable. Replacement factory cranks are better the originals and not that expensive.

Alan Cesar
Alan Cesar Dork
3/16/13 9:25 a.m.

The WRX crank is not nitrided, so that's not a concern.

jmr302 New Reader
3/16/13 11:14 p.m.

Are you sure they're not nitrided? I'm seeing forum threads saying they are but can't find anything definitive. I recently had my EJ22 shortblock freshened by Outfront Motorsports. They chose to replace my crank, which had already been ground once, rather than polishing it again for this reason. Maybe the EJ22 crank is different (besides thrust brg).

3/18/13 5:42 a.m.

Definitely some serious oil starvation happened here. I would advise that you also install a baffle plate and a set of oil pressure/temperature gauges if you would like to keep this car running on the track :)

Alan Cesar
Alan Cesar Dork
3/22/13 4:58 p.m.

We just confirmed with Mach V Motorsports: They were only nitrided from 2008 through 2010 or 2011. It's not a concern with our EJ205.

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