Mechanics

PISTON BROKE

1989 Jeep Wrangler

Engine Mechanical problem
1989 Jeep Wrangler 4 cyl Four Wheel Drive Manual 80,000 miles

I have never had a piston just break. The engine started rapping bad like something just broke. I was thinking it might be a wrist pin. As I attempted to find the problkem I found the piston broke on the back side on number 3 piston. It is a fresh break the whole part that is broke. The cylinder doesn't look scared nor can I see anything the piston could have hit to make it break. I am thinking of putting a new piston in and putting the motor back together but I wonder why the piston broke and if it will just break again. It is a 2.5 liter. I pulled down three of the mian bearings and they show very little wearaand no scaring. The rod bearing for number three cylinder shows some wear but it didn't seize or turn. The driver of the vehicle (my brother in law) lugs the motor more than he races it. My question is I guess does anybody have an idea why the piston broke?
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Hrvaughn81
March 29, 2010.



I have the same problem in my 2000 wrangler with 150k mi. My mechanic said that the pistons are made about 4 times thinner than than the older engines because Chrysler decided to go cheaper. He showed me the difference and most definitely thinner!Replace all of them with the older thicker pistons and should be fine!


Tiny
Richfirefighter14
Apr 7, 2012.