Mitsubishi Engine Teardown Shows What Happens When A Piston Explodes

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Boost is a hell of a drug. One minute it could have you on top of the world, delivering tons of power and torque to help you set a personal best lap time at your local track. The next minute, it could have you on the side of the track with oil pouring from underneath your car. We’re betting that’s exactly what happened to whomever used this turbocharged Mitsubishi engine last.

Eric from the I Do Cars YouTube channel wanted to see exactly how this Mitsubishi 4B11T, taken out of a Lancer Ralliart, met its end. From the jump we can see a massive hole in the block, with lots of surrounding damage. It only gets worse once Eric digs deeper.

 

Because this engine wasn’t very high-mileage, there are surfaces that looks surprisingly clean. The timing chain area is like-new, and the cylinder head isn’t stained by years of old, unchanged oil. But after removing the camshafts, Eric points out damage to the journals means these parts still might not be reusable, signaling the carnage to come.

Removing the cylinder head reveals the main problem area: Cylinder three, or what’s left of it, anyway. The piston looks to have literally exploded, with the top portion loose in the cylinder and splitting into pieces. The oil pan is full of giant pieces of piston, rod, bearing, and block material. The incident was so severe that it broke the block’s base plate into two pieces. This must’ve felt like a grenade exploding in the engine bay. 

Eric suspects there must’ve been a massive amount of boost going into this engine when it gave out, given the pure destruction that resulted from the failure. The wear on the connecting rod bearings that survived suggest there might’ve been a shortage of oil and lots of high rpm, too. Not a great combination for keeping an engine healthy.

Boost is a cruel mistress. 

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