Disassembling our Subaru WRX engine: No instructions required | Redline Updates - Hagerty Media

We’ve had our fun with this 300,000-mile Subaru WRX. Now it’s time to get down to business and tear it apart. Davin’s never touched a Subaru before, but how hard can it possibly be? Unscrew a few bolts there, cut a couple of zip ties here, and maybe break out a hammer and chisel and it should fall apart … right?

This 2002 Impreza’s 2.0-liter turbocharged flat-four engine is a touch different from the V-8s Davin’s used to dealing with, but that’s a minor setback. “I’m gonna start somewhere, and I’m gonna finish … with just a block … somewhere,” says Davin. (That’s the universal engine tear-down process, by the way. No flaws found.)

First up, Davin has to remove all of the accessory pieces, starting with the power steering pump. Quickly, he realizes how cumbersome this tear-down will be, given the amount of zip-ties and hose clamps he’ll have to work his way through. After removing the wiring harness and making a quick fish joke, (we’re sure that bass you caught was roughly that size, pal) the intake manifold comes off without much fuss. Good news! The intake ports are nice and clean.

With the aftermarket crank pulley removed, (at least 10 horsepower) the timing belt cover is up next. Bolts immediately start stripping in protest, and Davin has to resort to … persuasive methods to get the belt cover off. (Be sure to note the Rock Auto tip of the day here; it may come in handy when you’re dealing with ornery fasteners!)

Next up are the turbocharged and one of the coolant passages across the top of the head. Those come off easy, but after Davin flips the engine over and begins to pick away at the exhaust, rust and rotted fasteners fight back once again. nothing a chisel and a pry-bar can’t fix! “Might not be pretty, but I win every time here,” he jokes.

Peering into the exhaust ports, Davin notices a few issues with carbon buildup and oil leaking through the valve guides. With the oil pan removed (those keeping score at home, that’s Davin, 5, Subaru, 0), it’s time to really get into the internals of this motor. Thankfully, nothing puts up much of a fuss, and within no time, Davin ends up right where he said he would: A block (split in two), a bunch of parts, a few casualties, and quite a bit of sand—wonder how that got there? (Last episode should give you a clue.)

Stay tuned next week as parts head to the washer, then to their necessary shops, and Davin and team begin to bring this Subaru flat-four back to life.

Thanks to our sponsor RockAuto.com, an auto parts retailer founded in 1999 by automotive engineers with two goals: Liberate information hidden behind the auto parts store counter (by listing all available parts, not just what one store stocks or one counter-person knows), and make auto parts affordable so vehicles of all ages can be kept reliable and fun to drive. Visit RockAuto.com to order auto parts online 24 hours a day, 7 days a week, and have them conveniently delivered to your door. Need help finding parts or placing an order? Visit RockAuto’s Help pages for further assistance.