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Spun bearing - what type of machine work should I be expecting? Pic heavy
Forged LQ9 - Not entirely sure what caused the problem. Though my hunch is low oil pressure(reused an old oil pump-) or bad rebuilt job. I bought this shortblock locally with 0 miles on rebuilt got roughly 5k miles with a lot of runs already. what do you guys think?
I bought melling oil pump + an oil press sensor now so I would be able to catch that issue sooner.
luckily I felt the vibration and tore it down before it knocked.
Regardless I will need to take it to a machine shop to get repaired. What kind of work should I be expecting-ball park figures $$? I have never taken a block for a rebuild so i'd like to have some idea and not just drop it off with an open credit card lol
Now I do have 2 options
1. Repair this shortblock. block and caps appears to be fine? looks like 2 rods started to spin-are these typically replaced? or machined?
Not sure what work the crank needs but I do have a good spare crank if needed. Likely need line hone or maybe not? need new bearings for sure.
2. I have a spare lq9 that has a blow by, maybe switch over my forged rods/piston to that block instead? all it would need is maybe a light hone to the cylinder? and new piston rings?
Thoughs/feedback- Just trying to learn this bottom end rebuilding things
Forged LQ9 - Not entirely sure what caused the problem. Though my hunch is low oil pressure(reused an old oil pump-) or bad rebuilt job. I bought this shortblock locally with 0 miles on rebuilt got roughly 5k miles with a lot of runs already. what do you guys think?
I bought melling oil pump + an oil press sensor now so I would be able to catch that issue sooner.
luckily I felt the vibration and tore it down before it knocked.
Regardless I will need to take it to a machine shop to get repaired. What kind of work should I be expecting-ball park figures $$? I have never taken a block for a rebuild so i'd like to have some idea and not just drop it off with an open credit card lol
Now I do have 2 options
1. Repair this shortblock. block and caps appears to be fine? looks like 2 rods started to spin-are these typically replaced? or machined?
Not sure what work the crank needs but I do have a good spare crank if needed. Likely need line hone or maybe not? need new bearings for sure.
2. I have a spare lq9 that has a blow by, maybe switch over my forged rods/piston to that block instead? all it would need is maybe a light hone to the cylinder? and new piston rings?
Thoughs/feedback- Just trying to learn this bottom end rebuilding things
Pricing will vary, depending on where you are. Your rods will need a hone, and I’d have all 8 looked at personally. Block won’t need changed, as this is mostly bearing damage except the hot spot on the rod. Crank could possibly need turned…hard to tell from pics…might polish. You have a spare, so that’s likely the way to go. All of this will boil down to what your machinist tells you. Let them measure everything and give you their recommendations.
Tearing an engine down in a situation like this should be done in an investigative manner. There’s a lot of stories to be told if you know what to look for, but it’s a process that needs to move slowly and purposely. Too late now obviously, as you have it all apart. Blackened bearings means they were hot and usually means it’s because oil temps were high. I see funky bearing wear on one of the rod bearing pairs…did you over-rev this thing? Did you have oil pressure issues on a gauge, or perhaps were you starving this thing by means of high g-forces such as road racing or maybe super heavy braking or launches without the proper oil containment pieces in the oil pan? What oil were you running? Are you running an oil cooler? Is this a turbo or supercharged application that would be harder on oil? Tell us more info I guess is what I’m getting at…
It looks like it had low to no oil pressure.
He mentioned buying an oil pressure sensor so he could observe oil pressure this time around. So maybe was driving blind?
Pricing will vary, depending on where you are. Your rods will need a hone, and I’d have all 8 looked at personally. Block won’t need changed, as this is mostly bearing damage except the hot spot on the rod. Crank could possibly need turned…hard to tell from pics…might polish. You have a spare, so that’s likely the way to go. All of this will boil down to what your machinist tells you. Let them measure everything and give you their recommendations.
Tearing an engine down in a situation like this should be done in an investigative manner. There’s a lot of stories to be told if you know what to look for, but it’s a process that needs to move slowly and purposely. Too late now obviously, as you have it all apart. Blackened bearings means they were hot and usually means it’s because oil temps were high. I see funky bearing wear on one of the rod bearing pairs…did you over-rev this thing? Did you have oil pressure issues on a gauge, or perhaps were you starving this thing by means of high g-forces such as road racing or maybe super heavy braking or launches without the proper oil containment pieces in the oil pan? What oil were you running? Are you running an oil cooler? Is this a turbo or supercharged application that would be harder on oil? Tell us more info I guess is what I’m getting at…
Thanks for the feedback.
Turbo setup oil temp is typically between 200-210* and is pretty consistent so I didnt check what the oil temp was when this occurred. I opted not to run oil cooler because that seems to be normal- conventional 10w30 oil.
Not road coarse but multiple back to back back road drags ~7200-7500rpms this makes about 900whp. All factory oil pan guard is there but it is a GTO oil pan so maybe oil starvation on hard acceleration?
Ill keep that in mind next time, I opened it up as I was thinking it was my cam. It had a vibration that I havent experience before- The cam and bearing had very minor scuff so I was confused and just tore into the bottom to see.
In regards to the piston rings= would I be able to reuse the piston rings since they have been broken into or is it recommended to rehone the cylinder again and replace the rings/break in a new set?
Originally Posted by RonSSNova
It looks like it had low to no oil pressure.
He mentioned buying an oil pressure sensor so he could observe oil pressure this time around. So maybe was driving blind?
I had one originally but I ended up pinching those little plastic tubing that it leaked. Removed it for the time being and this happened. When I first had the new engine in, it was good but a lot could have happened from then till now.
I ordered a PLX sensor so I can log in this time around.
Thanks for the feedback.
Turbo setup oil temp is typically between 200-210* and is pretty consistent so I didnt check what the oil temp was when this occurred. I opted not to run oil cooler because that seems to be normal- conventional 10w30 oil.
Not road coarse but multiple back to back back road drags ~7200-7500rpms this makes about 900whp. All factory oil pan guard is there but it is a GTO oil pan so maybe oil starvation on hard acceleration?
Ill keep that in mind next time, I opened it up as I was thinking it was my cam. It had a vibration that I havent experience before- The cam and bearing had very minor scuff so I was confused and just tore into the bottom to see.
In regards to the piston rings= would I be able to reuse the piston rings since they have been broken into or is it recommended to rehone the cylinder again and replace the rings/break in a new set?
I had one originally but I ended up pinching those little plastic tubing that it leaked. Removed it for the time being and this happened. When I first had the new engine in, it was good but a lot could have happened from then till now.
I ordered a PLX sensor so I can log in this time around.
Why chance it? Get a new ring pack and have the shop ballhone (dingleberry hone) the cylinders for quick ring seal. Ring seal is everything, even with forced induction. Your looking at a couple hundred bucks.
It looks like it had low to no oil pressure.
He mentioned buying an oil pressure sensor so he could observe oil pressure this time around. So maybe was driving blind?
That's how I read it, Ron. Man, of all the vital signs an engine can display, none are as important as oil pressure. Glad the OP has installed some sort warning system.......
Why chance it? Get a new ring pack and have the shop ballhone (dingleberry hone) the cylinders for quick ring seal. Ring seal is everything, even with forced induction. Your looking at a couple hundred bucks.
Exactly, you've got it apart down to basically the bones, so may as well do it all "while you're in there."
05-28-2022, 09:32 PM
Spun bearing - what type of machine work should I be expecting? Pic heavy 
) or bad rebuilt job. I bought this shortblock locally with 0 miles on rebuilt got roughly 5k miles with a lot of runs already. what do you guys think?
