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07-14-2011, 08:15 PM
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#1 | | Member
Join Date: Jun 2007 Location: Maryland
Posts: 289
Car: '89 z28 Engine: 406 Transmission: T56 Axle/Gears: 12 bolt 4.10 | Blown head gasket, only to find pistons upside-down... The picture says it all... Where do I go from here? The valves don't look bent but should I pressure test them? I have to pull the motor and swap the pistons around; will I have to re-hang the rods so they can all go back into the same bores? | | | |
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07-15-2011, 12:24 AM
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#2 | | Moderator
Join Date: Jan 2000 Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,933
Car: 1984 Z28 Hardtop / 1988 IROC T-top Engine: 383 Carb / 305 TPI Transmission: 4L60 / T-5 Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt | Re: Blown head gasket, only to find pistons upside-down... Getting the heads checked would be a good idea. Honing and re-ringing should be enough to swap the pistons from side to side. |
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07-15-2011, 12:12 PM
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#3 | | Senior Member
Join Date: May 2011 Location: in a huge granite cave
Posts: 1,198
Car: '84 & '86 Camaros Engine: building turbo 5.3L, & 3.4L Transmission: 4L80E & 700R-4 Axle/Gears: TBD & 3.42:1 | Re: Blown head gasket, only to find pistons upside-down... What about the rod offset? |
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07-15-2011, 12:32 PM
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#4 | | Moderator
Join Date: Jan 2000 Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,933
Car: 1984 Z28 Hardtop / 1988 IROC T-top Engine: 383 Carb / 305 TPI Transmission: 4L60 / T-5 Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt | Re: Blown head gasket, only to find pistons upside-down... They're aftermarket pistons, I doubt they have a rod offset. |
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07-15-2011, 12:36 PM
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#5 | | Member
Join Date: Jun 2007 Location: Maryland
Posts: 289
Car: '89 z28 Engine: 406 Transmission: T56 Axle/Gears: 12 bolt 4.10 | Re: Blown head gasket, only to find pistons upside-down... Is a re-ring imperative? The motor has less than 4k miles on it. |
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07-15-2011, 12:38 PM
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#6 | | Moderator
Join Date: Jan 2000 Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,933
Car: 1984 Z28 Hardtop / 1988 IROC T-top Engine: 383 Carb / 305 TPI Transmission: 4L60 / T-5 Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt | Re: Blown head gasket, only to find pistons upside-down... The rings are broken-in to the cylinders they're in now. They won't seal in different ones. |
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07-15-2011, 12:41 PM
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#7 | | Moderator
Join Date: Jan 2000 Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,933
Car: 1984 Z28 Hardtop / 1988 IROC T-top Engine: 383 Carb / 305 TPI Transmission: 4L60 / T-5 Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt | Re: Blown head gasket, only to find pistons upside-down... Quote:
Originally Posted by ronnjonn What about the rod offset? | Ahhh ok, I see what you mean... yeah, they'll probably have to be rehung. |
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07-15-2011, 12:53 PM
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#8 | | Member
Join Date: Jun 2007 Location: Maryland
Posts: 289
Car: '89 z28 Engine: 406 Transmission: T56 Axle/Gears: 12 bolt 4.10 | Re: Blown head gasket, only to find pistons upside-down... Quote:
Originally Posted by Apeiron Ahhh ok, I see what you mean... yeah, they'll probably have to be rehung. | I'm willing to bet the guy who put the motor together put half the pistons in wrong... won't know 'til I pull it. http://www.jepistons.com/TechCorner/Pin-Offset.aspx
The pistons did seem really loud when cold. |
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07-15-2011, 01:01 PM
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#9 | | Moderator
Join Date: Jan 2000 Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,933
Car: 1984 Z28 Hardtop / 1988 IROC T-top Engine: 383 Carb / 305 TPI Transmission: 4L60 / T-5 Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt | Re: Blown head gasket, only to find pistons upside-down... Those pistons probably don't even have pin offset. The problem is the connecting rods. They have a side that has to face the other rod on the pin, and a side that faces the crank throw. Essentially you need to turn the piston 180 degrees without turning the rod, which can't be done without taking the rods off. |
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07-15-2011, 04:22 PM
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#10 | | Junior Member
Join Date: Jun 2011 Location: Austin, TX
Posts: 24
Car: 92 B4C/1LE | Re: Blown head gasket, only to find pistons upside-down... Quote:
Originally Posted by kerplunk318 I'm willing to bet the guy who put the motor together put half the pistons in wrong... won't know 'til I pull it. | I'd be having a little chat with that guy. |
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07-15-2011, 06:14 PM
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#11 | | Supreme Member
Join Date: Mar 2007 Location: Ft Worth Tx
Posts: 3,510
Car: 91 Camaro RS Engine: empty bay (for now) Transmission: Built T-56 Axle/Gears: 3.42 stock posi disc | Re: Blown head gasket, only to find pistons upside-down... Thats just bad workmanship. you can clearly see were the valve was contacting the piston, so they are most likely damamged in one way or another. Best thing to do would be to pull each rod/piston assembly at a time, pull the piston off the rod, and rotate it 180 degrees. then reinstall with new spirolocks on the pins. and i would most def have the heads checked out for bent/damaged valves. |
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07-15-2011, 06:14 PM
| | ThirdGen 1992 Camaro
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