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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jbreeves85C10 on November 21, 2013, 04:01:47 pm
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Let me start by stating that I am by no means a mechanic :-) I have always done small projects and maintenance so this is my first major, to me, engine project. I had a valve and rod crap the bed and it did this to my piston. My question is: Is the piston shot or is it still fine?
Thanks in advance.
JB
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Do you know why this happened? What did it do to the head? Need to determine and fix the cause so it doesn't happen again.
I had something like this happen under warranty on a diesel engine. They reused the piston and installed a set of new rod bearings for that rod after determining the rod had not been damaged. Other than the obvious damage in your photo is there any other damage to the lower end?
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Everything seems to be tight and intact and it did not crack the piston...just scuffed it up. I bought all new rods, valves, rockers, lifters, springs, etc so basically gutting the heads and rebuilding while I have it apart. I'm not sure what caused the valve to stick and bend but it did :-)
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Okay. I'm assuming the "etc." in your post means new rod and main bearings too. If you are installing all new rods as stated you might as well check your cylinder bores and if they are within specs consider honing them and adding new rings. My $.02
Keep us advised as to how it goes.
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I personally wouldn't trust that, those are . Are you wanting to put it back together and run it?
If you bought new rods (not sure why) I would buy new pistons. I wouldn't put new stuff in there and run those. The motor is bored already so you need to get it checked before buying pistons.
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I'm wondering if he means pushrods when he says "rods". I thought he was talking connecting rods, but I reread thinking pushrods and it makes way more sense.
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It was push rods. My fault. I figured while I had it apart I would replace all of the small stuff :-)
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If the pushrods aren't bent there is no reason to replace them.
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Jb, Your post leaves many questions due to how you wrote it, but I think we are getting to the bottom of it.
Can we assume...something happened (valve stuck in guide) & piston came up, hitting the valve (making the marks) & then bending the pushrod on that valve?
The piston isn't great, but would not scare me enough to not be sticking a head on & running it. The real concern is the lifter/cam lobe on that valve...you likely will have damage there. Research that & it will tell you if you need to disassemble farther. My Two Cents, Lorne
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And the valve guide, it looks like 4 distinct marks at 4 different angles so the valve is definitely bent so make sure the guide isn't ovaled out. simple bushing will fix this if you went cheapest route...