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Broken piston skirt in 94 xj??

Jbaddick17

NAXJA Forum User
Location
PA
So here is the story, I’m looking to buy this jeep for a steal, kid says it’s blown up but it has great oil pressure, runs smooth and all, no smoke... but I had an xj before with piston damage and it sounded deeper than this, any idea if this could be a snapped skirt? Or valve train? Possibly even flex plate... video coming soon
 
Based on the rep rate and even spacing of the tapping, it's idling about 840 rpm and tapping twice per revolution. Seems like that would rule out valve train? Any blow-by out the oil cap? Sounds like flexplate bolts to me. The floor plan fix looks like they just slapped some sheet metal over top of the rotten sheet metal.
 
Based on the rep rate and even spacing of the tapping, it's idling about 840 rpm and tapping twice per revolution. Seems like that would rule out valve train? Any blow-by out the oil cap? Sounds like flexplate bolts to me. The floor plan fix looks like they just slapped some sheet metal over top of the rotten sheet metal.




DOH! My math was wrong there. About 7 taps per second would be every other revolution. Which would point to valve train.
 
No , no blow by or smoke out the tail pipe so I guess I’ll check the flex plate, but still not convinced it didn’t bend a pushrod, it happened while he was doing a burnout so my guess might be it was over revved and bent a pushrod or even broke it
 
But yes he has all new floor pans from quadratec, that’s what makes me want the Jeep haha, just can’t afford a new motor again as a college kid, first xj needed a motor and cost me a grand for a JY motor and the install
 
Heres my two cents, take it any way you want. You say it runs smooth, which rules out a bad, bent, broken, or otherwise faulty pushrod. If it was a bad, bent, broken, or otherwise shitty pushrod, trust me, it would not run smooth. Do yourself a favor, dont guess at any of this, check these things out. Flexplate bolts, maybe.....if you are suspicious then slide under there and check them, its easy.
The only way to check for a cracked piston skirt is to drop the oil pan. I had this issue for a LONG time. The noise started at about 60K miles. The noise, clacking that made it sound like a diesel engine, got a little louder over the years but eventually stabilized. I finally dropped the pan at around 210K and immediately saw the missing skirt. The chunks were in the pan. I racked up all those miles, on road and off road, with that damn clacking noise and it never came apart. It did the same as you are describing, 'went away' at 2000rpm. I continued to drive the damn thing until 219K miles, when I shut it down for good to rebuild the engine. The engine factory used cheap crap parts in the engines, but it still ran a long time. So my advice is, if you can at least afford to drop the oil pan to check the skirts, do that. If it is the skirts and you cant afford the rebuild right away, so what, just run the damn thing. At least you know what the issue is and you wont be constantly trying to figure it out. You dont have to beat the hell out of it, although I never held back with mine and occasionally hit 4000rpm and that piston (#6) never came apart, but will probably be ok for quite a while until you are ready to rebuild it, which doesnt cost all that much either! Good luck man, any questions just ask. Good Luck!
 
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