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89 RT4WD Wagon
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35 Posts
Discussion Starter #1 (Edited)
So I'm an idiot and f-ed this up. 2 Pistons in the hole and 2 to go. Drop number 3 in and give it a couple taps and it stop and gets solid sounding. What should you do? STOP!!! and try again. Me I give it one more wack because one of my other pistons had just go slightly crooked and stopped so I thought thats what was going on. No go so time to pull the ring compressor off and try again... Shit did I really just do that...ahhhhh... I'm a moron... And here's the proof...






So yeah no need to tell me I'm a complete idiot I'm doing a good enough job of that myself. What I want to know is am I correct in guessing this piston is nothing but a paper weight now? I'll need to get a new one and try to be a bit more intelligent next time?
 

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98 Civic CX-T on E85
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1,797 Posts
ouch man! i would probably replace it...its better to know that you have all perfect pistons installed vs worrying about one piston failing...
 

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89 RT4WD Wagon
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35 Posts
Discussion Starter #6
It's just an NPR P29 so nothing exotic or expensive. I had pistons and bores oiled up. I've got one of those spring compressors thats basically a coiled up piece of sheet metal with a ratcheting clamp around the outside. The cheap one. The ring just popped out between the block and compressor and I didn't realize it.

Live and learn I guess but I just keep kicking myself over and over and over again.

Does anyone know anywhere I can buy just one NPR P29. Pistons always seem to be solid in full sets. Oh yeah it's a .5mm overbore one too..
 

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Formally known as SPONSOREDCRX
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3,566 Posts
It's just an NPR P29 so nothing exotic or expensive. I had pistons and bores oiled up. I've got one of those spring compressors thats basically a coiled up piece of sheet metal with a ratcheting clamp around the outside. The cheap one. The ring just popped out between the block and compressor and I didn't realize it.

Live and learn I guess but I just keep kicking myself over and over and over again.

Does anyone know anywhere I can buy just one NPR P29. Pistons always seem to be solid in full sets. Oh yeah it's a .5mm overbore one too..
Yea doesnt seem like you fucked up to bad. The cost of a piston for a learning experience seems pretty inexpensive. Dont beat yourself up.

And I would say my friend has a piston but they are std size. =/
 

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1988 Honda CRX
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6,676 Posts
The piston appears unusable to me.

There appears to be a crack in the land between the second ring and the oil control ring. That means the land may completely fail and the ring cannot seal against the side of the grove at that point. Rings not only seal against the bore, they also need to seal against the piston.

I would buy a set of pistons, they are cheap.

Before I put it together again, I would run a scraper around the chamfer at the top of the bore a few times so the rings go in easier. When you bore it, you actually reove most of the original chamfer, so a bit of a scrape only restores the original.

Slide the piston in the bore until the ring compressor bears on the deck. gently tap the ring compressor down even all the way round. repeat as many times as necessary to be real confident it is firmly in place. It is best if you have a helper to hold down on the ring compressor as you do this.

With the end of the wooden handle on a decent sized hammer, gently tap the pston top a few times to see it moves easily and smoothly, but STOP before the bottom ring gets to close to the bore. If you have ANY doubts, stop and start over.

Once everything is lined up and moving as it should, give the piston top one firm blow with the handle of the hammer so the rings pass into the bore in one swift movement with no chance to pop out or rebound. If it stops short, pull it out and start again from fresh. A second hit always risks hitting down on a ring that has popped out.
 

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Banned
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1,234 Posts
Doesnt look cracked to me. I would file that shit out, and call it good. In fact, Ive had to file used pistons out. You just file it out until the ring with slide all of the way around smooth, without catching. Call it a day.
 

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1988 Honda CRX
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6,676 Posts
In the top picture I agree it does not looked cracked.

I just blew up the bottom picture as big as it would go and it still appears cracked to me as best I can see in that picture. It also appears the dent is so deep that the ring would not be supported or sealed after the grove was filed to remove the bump at that point. Without seeing the piston for real and inspecting properly I still take the safe road.

Is it worth the risk for the price of a set of cast pistons?
 

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92 VX
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22 Posts
get a bigger hammer, simple fix lol. For real 1) measure bore for taper and width. 2) tighten the ring compressor. 3) File ring lands.
 

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89 RT4WD Wagon
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35 Posts
Discussion Starter #15
Well I just placed an order for a full set of new NPR pistons for another $80. Not an end of the world screw up just slows me down for a few more days until the new piston comes in. I was hoping to get the bottom end put back together this weekend and maybe even start putting the short block in the car while I was waiting for the head to be finished up. My backup car to get to work in is not so ideal so I was in a hurry to get this done and of course if you're in a hurry this is what happens.

I have to swing by the machine shop today and drop all my valves off anyways so I will see what the machinist thinks about the piston.
 

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the short bus
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1,065 Posts
Get some JB weld and throw that shit back in there. then you can build my motor. :D

Nah seriously... It looks like a fucked ringland happened or will happen after a couple pulls. Once the piston's ringland got bashed like that I would say game over. If youre a gangster take the risk. I wouldnt tho.
 

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1,885 Posts
oof. oh well good learning lesson. don't screw it up again or you'll be BANNED! :bash:

just kidding :bigok:

-Luke
 
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