Have a 2006zo6 corvette with 30k miles. Noticed the oil pressure dropped from normal while driving the other day. Was about 2 miles from my other garage with lift so I put it up and cut filter and sure enough bearing material.
Tore it apart from underneath on lift and found no 4 main bearing was going. Didn't spin. Got numbers of bearings but can't locate. Can someone with gm experience help.
Ls7 motor. All stock. #4 main
Uppers numbers 12599599
Pulled #3 main also and it looked fine. Small scratches but only in top silver coating and no brass showing. Inspected all other locations without pulling it apart and they to looked good.
Crank has some copper color to it on #4 but couldn't feel any ridges or anything. Any suggestions for polishing. Not sure if that would do more harm than good. Or if I should just put new bearing in and watch things close with some filter cutting. Car is mint and great to drive.
When I was taking it apart the one side main bolt that comes thru side of the block was only finger tight on #4. Assuming that is what led to the failure. I'll be checking them all on reassembly.
Any help or suggestions with this motor would be appreciated. First time digging into an ls7 motor. Built many others before.
Configuration: 3350#, 555 C.I.,
60 - 1.24
1/8 - 5.69@ 123MPH
1/4 - 9.03& 152MPH
3700#+210lb driver, FULL interior, through mufflers, 10.5 tire.
60'-1.333 (IN 4000ft DA! Joisy Math excluded; 1.25sec using JOISY MATH.)
1/4 - 9.60@144MPH
Outstanding find! I have a '12 w/LS3 will be watching with interest. I too am an LS virgin. Good luck!
Illegitimi non carborundum
gm part# is 89017877, looks like plenty of stock avail.
Thanks for the info. Have rod bearing numbers?
Are all the bearings in these stock ls7s the same reason in all is I know the ls7 motors were hand built for the z06 cars. They wouldn't mismatch to better fit things would they?
Hand built or not there is always the potential for a "production variance", to use some cranks or rods that aren't standard.
Illegitimi non carborundum
Bearings are not usually a major a wear item.
If there is wear or scuffing on a bearing there is a reason, no oil, no oil pressure, aerated oil, bent crank, improper oil clearance. You need to find the problem. Copper is in the bearing composition, if it has been deposited on the crankshaft there is a problem you need to find.
Crank can be polished in place with 400 -600 wet or dry paper, but it will make debris as it removes the copper scoring, but copper is soft.
In engine work there is the shortcut, or there is not the shortcut. The problem happened.....now find out why, and fix it.
Thanks. Like in said the problem I believe was the side bolt was completely loose when I was taking the main of that went. The bearing side on that side was worn more...
I was going to polish the crank gently. My father was a tool maker for years building precision tooling and has much experience in such fine detail.
I'm planning on pulling the 4 rod caps adjacent the main to inspect them as well.
When we polish the crank due to the debris I know will occur I plan to put a small amount of playdo in the crank hole just to plug it off to prevent debris from going any further. And also place the hole down. I'll then after pick it all back out. This should keep the dust and debris from getting into oil passages.
I'll to be safe plastigage the mains unless my engine machine who I missed Friday can confirm the numbers are infact stock size. I still with gage them to be ultra safe
You can also put shaving cream in the holes. Never tried play dough but sounds good. Sounds like somebody has been in there before. I hope it works out for you but does not sound too good.
Yeah that would probably work too.
I only changed the oil one time prior. Hardly never drive the car. The zo6 has a dry sump that requires special oil drain and change procedure. It's possible in the past that someone may have not done it correctly. For first two years oil pressure was always above 50psi and even hit 90psi when on it. I'm a gage watcher and saw it drop within I bet a 3 mile stretch. And immediately pulled it into garage and started checking. Fortunately I was near my place.
It's not as bad as it sounds and I know nothing got too heated.. Absolutely no burning at all. When it happened the oil temp was 190ish. Motor runs at 205ish.
I'll watch it close again after putting things back together. I'll polish carefully the crank to remove deposits or any high spots. I'll check the clearance of this one vs a good one. Like I said the next main still had coating on it. Looked brand new.
rods are 89017811
Checked adjacent rod bearing and they are perfect.
Very strange this one main is beat up.
Got the bearings in the car today and everything torqued down. Getting the bearings in was not the easiest of tasks that is for sure but got them up in.
Tomorrow I'll get it all put together.
Put some miles on the car and all seems fine. Oil pressure at cold if above 3000 his almost 90 like stock... After hot about, 65-70. Idle hot stays between 25-35 depending on oil temp. Oil temp stays at 160-180. Checked oil color and it hasn't changed. Last time with under 100 miles it was black.
Going to pull filter in next few days and cut it and check. Suspect a little residual but second filter change it better be clean.
well final update...
Drove the car now about 400 miles and cut filter and checked oil...Filter only had 3-4 specs of bearing material (far less than I suspected would be still present despite efforts to clean everything. Impossible to get it all. So I was pleased with that result. Oil after that many miles was still very clean and looked like it came out of jug. Before bearing change, after about 100 miles it was black as coal.
Oil pressures seem very good so I am calling it success at this point.
Pays to know your engine and STOP when you suspect something is wrong. Everyone I spoke to said just keep running it...the motor surely would have went.
You definitely earned yourself an Attaboy! Well done! I've got an LS3 w/dry sump, you can bet I'll keep an eye on the oil pressure.
Illegitimi non carborundum
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