Lets play the guess what happened game.
Thread Starter
Joined: Apr 2007
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From: JunkYard
Lets play the guess what happened game. I'm stumped on this one.
Stock LQ4 bottom end with floating rods. Engine saw a boost spike. Started making a tapping like a bad lifter. Engine was shut down right after but has been started for diagnosis.
No sign of dentenation, No misfires, No spun bearings or damaged rod pin bushings, No butted ring lands, no metal in oil, rods look fine, piston looks fine other than where it came in contact with crank. Bore looks fine too.
Only damage is bottom of piston hitting high spot on crank counter weight. This is on number 2 and number 7 cylinders only. I also should note those to pistons come up short from reaching the top of the deck like the other 6.
Any one ever see anything like this???
Stock LQ4 bottom end with floating rods. Engine saw a boost spike. Started making a tapping like a bad lifter. Engine was shut down right after but has been started for diagnosis.
No sign of dentenation, No misfires, No spun bearings or damaged rod pin bushings, No butted ring lands, no metal in oil, rods look fine, piston looks fine other than where it came in contact with crank. Bore looks fine too.
Only damage is bottom of piston hitting high spot on crank counter weight. This is on number 2 and number 7 cylinders only. I also should note those to pistons come up short from reaching the top of the deck like the other 6.
Any one ever see anything like this???
Last edited by 1FastBrick; Nov 18, 2017 at 11:20 PM.
Thread Starter
Joined: Apr 2007
Posts: 9,723
Likes: 629
From: JunkYard
Thread Starter
Joined: Apr 2007
Posts: 9,723
Likes: 629
From: JunkYard
I had a Duramax engine like this and it was the pin bushing in the rod that went out.
Every thing looks good as far as I can tell. I honestly thought there would be something other than what I am seeing.
Every thing looks good as far as I can tell. I honestly thought there would be something other than what I am seeing.
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Verdad Gallardo Thread Starter
Joined: Apr 2007
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From: JunkYard
Detonation = Bent Rod Hi Brick, my guess is bent rods.
My experience is with the EJ-25 Subaru engine when detonated.
The rods bend with to visible damage to the piston.
Lance
My experience is with the EJ-25 Subaru engine when detonated.
The rods bend with to visible damage to the piston.
Lance
Thread Starter
Joined: Apr 2007
Posts: 9,723
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From: JunkYard
Bent rod is the answer.
appears to be approx .050 shorter.
It appears to have side loaded in the direction of the pin.
Now, the tuff decision. Should I reuse the 2 pistons and just replace the rod or should I put a piston and rod in those 2 holes???
appears to be approx .050 shorter.
It appears to have side loaded in the direction of the pin.
Now, the tuff decision. Should I reuse the 2 pistons and just replace the rod or should I put a piston and rod in those 2 holes???
Thread Starter
Joined: Apr 2007
Posts: 9,723
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From: JunkYard
Thread Starter
Joined: Apr 2007
Posts: 9,723
Likes: 629
From: JunkYard
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You boost the engine and want to reuse those pistons? The rods bent and you are going to reuse ANY of the rods? I think you need to rethink the entire bottom end. Obviously the rods can't handle what you want to do.
