Rod bolt torque? Engine broken!
#1
Rod bolt torque? Engine broken!
Ok, guys. I have a situation. I recently purchased a low mileage LS1 long block. When I got it, the guy told me I needed to retorque the rod and main bolts because he usually pulls a rod and main cap to check the condition of the bearings. The price for the engine was cheap enough and anyone can torque bolts so I told him i would take it. He gave me some spec of 15 ft/lbs and then add 85 degrees. He said I had to loosen the bolts first, then tighten to 15 lbs, then do the angle. Seeme
d like a lot of work so I called a local machinist that I have known since 2011. He has built a lot of LS engines and said all I needed to do was set my torque wrench to 35 ft/lbs and make sure my wrench clicked. As long as it clicked, I was good. I did that. Got the engine in and it sounded great on initial start up. Got to operating temp, revved it a few times in my garage and then took it for a drive around the block. Got on it a little bit and it was making a light knocking sound when I pulled back to my garage. I was pissed. The guy asked me if I had retorqued the bolts like he asked me to and I told him I trusted my machinist and didn't really know him. He said as much as it sucks to do now, I need to do it this torque plus angle method. I told him I did it like my machinist said and it is right. He still said I needed to do torque plus angle and that 35 sounded low. Anyway, drove it for almost 2 weeks and today it broke. Pulled the heads off and the back two pistons weren't hooked up anymore. He came over and pulled the pistons and said a rod bolt had broken. One of them has about one thread past the shank and the other has 4 or 5 threads showing before it broke. After reading online, I think the wrist pin failed, not the rod bolts. I think he owes me an emgine. What do you guys think?
d like a lot of work so I called a local machinist that I have known since 2011. He has built a lot of LS engines and said all I needed to do was set my torque wrench to 35 ft/lbs and make sure my wrench clicked. As long as it clicked, I was good. I did that. Got the engine in and it sounded great on initial start up. Got to operating temp, revved it a few times in my garage and then took it for a drive around the block. Got on it a little bit and it was making a light knocking sound when I pulled back to my garage. I was pissed. The guy asked me if I had retorqued the bolts like he asked me to and I told him I trusted my machinist and didn't really know him. He said as much as it sucks to do now, I need to do it this torque plus angle method. I told him I did it like my machinist said and it is right. He still said I needed to do torque plus angle and that 35 sounded low. Anyway, drove it for almost 2 weeks and today it broke. Pulled the heads off and the back two pistons weren't hooked up anymore. He came over and pulled the pistons and said a rod bolt had broken. One of them has about one thread past the shank and the other has 4 or 5 threads showing before it broke. After reading online, I think the wrist pin failed, not the rod bolts. I think he owes me an emgine. What do you guys think?
#4
Restricted User
Yeah sure, sounds like wrist pins to me.
#6
Looks like the wrist pins are where they are supposed to be and they don't look like they got hot. How can you justify blaming the wrist pins?
They have a torque procedure for a reason, now you know what that reason is.
They have a torque procedure for a reason, now you know what that reason is.
#7
OK. Do you see any reason the way I did it would cause the failure though? My machinist said on LS engines, he sees them anywhere from 27-35 ft/lbs. The guy I got the engine from along with another guy with a shop said they did some testing and the torque came up to between 48-53 ft/lbs but said they still didn't recommend doing torque only. If I take this guy to court, I want to have something to stick on him.
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#10
I was reading online and the way they described the sound of a bad wrist pin sounded like it would make exactly the same sound my engine did. That's why I think it could have been the wrist pins.
#11
#13
Well, I told him I wanted my old 5.3 with seized oil pump back and he gave it back. I don't see why I won't get my money back, too.
So you guys are saying this guy isn't at fault at all? He sold me an engine that broke!
So you guys are saying this guy isn't at fault at all? He sold me an engine that broke!
#14
TECH Addict
iTrader: (1)
Your an idiot. The world need to line up all you dumb people and just shoot you.
So in your little fucked up mind the guy that told you the PROPER ROD BOLT TORQUE PROCEDURE that you blatantly ignored should give you your money back?
You fucked up it's your fault it's in pieces now kick rocks.
So in your little fucked up mind the guy that told you the PROPER ROD BOLT TORQUE PROCEDURE that you blatantly ignored should give you your money back?
You fucked up it's your fault it's in pieces now kick rocks.
#16
TECH Senior Member
The machinist was wrong. The guy who sold you the engine was right. You did not listen to him OR look up actual procedure on rod bolts. He sold you an engine. It broke because YOU did a crappy job of tightening the rod bolts. Next time listen to someone who REALLY knows, backed up with your own research. Your machinist is that, not a mechanic. He is living in the past.
#18
TECH Junkie
iTrader: (4)
#20
Do a test,
torque two surviving rod bolts to 15ftlb now mark both of them at the 12 o'clock position. Tighten one of them to 35lbft and the other to 50lbft. Which bolt is closer to 90 degrees/3 o'clock?(i know the the spec is 85degrees but 90 is easy to see and is perfectly fine) i bet 50lbft is almost perfect.
torque two surviving rod bolts to 15ftlb now mark both of them at the 12 o'clock position. Tighten one of them to 35lbft and the other to 50lbft. Which bolt is closer to 90 degrees/3 o'clock?(i know the the spec is 85degrees but 90 is easy to see and is perfectly fine) i bet 50lbft is almost perfect.