accidentally damaged one piston... need some opinions - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

john891 · 05-08-2009, 09:02 PM

hey guys I have been searching and re-searching trying to figure out how i should go about this.

Motor= newly installed S13 SR

Long story kinda short: I was bleeding one of my lifters and I wasnt smart about reinstalling one of the cams. While turning over the motor by hand one of the exhaust valves hit the number two piston, broke off and damaged it slightly. (i took the head off to confirm this)
The #2 piston has 2 nicks in it and a hair line crack where the valve lodged itself.

Anyway. i have several good condition used SR pistons. I was just wondering if since i have several good condition used pistons if it would be OK to take the motor just enough to where i could take off the upper oil pan, slide the old piston out and and slide another one in. I have a spare head to put on and the motor and head studs/head gasket on the way. Other than the piston being slightly damaged the motor is in great shape.

Thoughts would be appreciated. thanks

Sileighty_85 · 05-08-2009, 09:22 PM

how the hell do you crack a pistion from just turning the engine over by hand??
I can understand maybe snapping a valve but cracking the piston??
Were you jumping up and down on the breaker bar??

The nicks are fine but if its really crack then you need to replace that piston

john891 · 05-09-2009, 09:11 AM

yes i was jumping up and down on the breaker bar dude.

besides the supernatural mechanical irregularity that has happened here- anyone else?

2fizzleforshizzle · 05-09-2009, 10:09 AM

U must be very strong or trun green when mad 2 break valves and crack pistons with hand!!

gotta240 · 05-09-2009, 10:17 AM

sounds like a LOT of force was applied to break that.

I would also be worried about the bearings on that cylinder.

*fliprayzin240sx* · 05-09-2009, 09:18 PM

Quote:

Originally Posted by gotta240

sounds like a LOT of force was applied to break that.

I would also be worried about the bearings on that cylinder.

and piston rings sealing.

If im in your situation and really wanna pull that piston out, I'd hone the cylinder a bit, toss some fresh rings and fresh rod bearing. The problem now is considering how much work youre doing to that 1 cylinder, might as well do all 4.

john891 · 05-09-2009, 11:56 PM

yeah i was thinking along those lines as well. Just sucks when you put a motor in and are ready to go and this kinda thing sets you back. thanks guys.

junbugs13 · 05-10-2009, 12:01 AM

u might as well just have it honed out install new rod bearings and piston rings be fine then it will be sure to run fine cuz sr parts are cheaper than rb so just do it now and not regret not doin it when you had the chance

john891 · 05-12-2009, 05:21 PM

well i took the motor partially out, rested the tranny on the core support, dropped the oil pans and slipped the new piston in. the cylinder and rings looks great so hopefully it works out!

05-08-2009, 09:02 PM	#1
john891 Leaky Injector Join Date: Jul 2005 Location: midlothian Posts: 57 Trader Rating: (1)	accidentally damaged one piston... need some opinions hey guys I have been searching and re-searching trying to figure out how i should go about this. Motor= newly installed S13 SR Long story kinda short: I was bleeding one of my lifters and I wasnt smart about reinstalling one of the cams. While turning over the motor by hand one of the exhaust valves hit the number two piston, broke off and damaged it slightly. (i took the head off to confirm this) The #2 piston has 2 nicks in it and a hair line crack where the valve lodged itself. Anyway. i have several good condition used SR pistons. I was just wondering if since i have several good condition used pistons if it would be OK to take the motor just enough to where i could take off the upper oil pan, slide the old piston out and and slide another one in. I have a spare head to put on and the motor and head studs/head gasket on the way. Other than the piston being slightly damaged the motor is in great shape. Thoughts would be appreciated. thanks __________________ Image exceeds forum limits of 400wide x 200 high. gold 89' SR'd coupe w/ silvia front

05-09-2009, 09:11 AM	#3
john891 Leaky Injector Join Date: Jul 2005 Location: midlothian Posts: 57 Trader Rating: (1)	yes i was jumping up and down on the breaker bar dude. besides the supernatural mechanical irregularity that has happened here- anyone else? __________________ Image exceeds forum limits of 400wide x 200 high. gold 89' SR'd coupe w/ silvia front

05-09-2009, 11:56 PM	#7
john891 Leaky Injector Join Date: Jul 2005 Location: midlothian Posts: 57 Trader Rating: (1)	yeah i was thinking along those lines as well. Just sucks when you put a motor in and are ready to go and this kinda thing sets you back. thanks guys. __________________ Image exceeds forum limits of 400wide x 200 high. gold 89' SR'd coupe w/ silvia front

05-12-2009, 05:21 PM	#9
john891 Leaky Injector Join Date: Jul 2005 Location: midlothian Posts: 57 Trader Rating: (1)	well i took the motor partially out, rested the tranny on the core support, dropped the oil pans and slipped the new piston in. the cylinder and rings looks great so hopefully it works out! __________________ Image exceeds forum limits of 400wide x 200 high. gold 89' SR'd coupe w/ silvia front

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05-08-2009, 09:22 PM	#2
Sileighty_85 Nissanaholic! Join Date: Dec 2006 Location: Wishing Back in Okinawa -_- Posts: 2,324 Trader Rating: (0)	how the hell do you crack a pistion from just turning the engine over by hand?? I can understand maybe snapping a valve but cracking the piston?? Were you jumping up and down on the breaker bar?? The nicks are fine but if its really crack then you need to replace that piston __________________ 後輪駆動車１番 1991 Built SR GT2871R -363whp 1998 S14 W/RB25- Rebuild in Progress

05-09-2009, 10:09 AM	#4
2fizzleforshizzle Join Date: May 2009 Location: Michigan Age: 22 Posts: 6 Trader Rating: (0)	U must be very strong or trun green when mad 2 break valves and crack pistons with hand!!

05-09-2009, 10:17 AM	#5
gotta240 Post Whore! Join Date: Dec 2005 Location: so cal Posts: 3,098 Trader Rating: (6)	sounds like a LOT of force was applied to break that. I would also be worried about the bearings on that cylinder.

05-10-2009, 12:01 AM	#8
junbugs13 Leaky Injector Join Date: May 2009 Location: riverside Age: 21 Posts: 64 Trader Rating: (0)	u might as well just have it honed out install new rod bearings and piston rings be fine then it will be sure to run fine cuz sr parts are cheaper than rb so just do it now and not regret not doin it when you had the chance