[Crazy Drywall Guy]

Valvoline 5-30 synthetic if I remember correctly

[Kerry]

Word to the wise. If u blow the front seal. Its not from lack of crankcase ventilation. Its from blow by 99% of the time on a stock motor from broke ring land. Compression is getting by the piston pressurizing the crankcase. Extra venting is not needed and not the problem.

In a way the front seal is kind of like a fuse letting you know their is a problem. very flimsily but adequate. Might even be a bad idea to replace it with the ls3 version.

Heres what mine looked after blowing the front seal.

[Kerry]

Did u say how many miles on the motor?

[Puddin]

Originally Posted by Crazy Drywall Guy

Yes,they were still on the piston until I pulled it out of the cylinder.

At least you had a little luck there. Hopefully nothing else is too banged up.

[Crazy Drywall Guy]

Originally Posted by Kerry

Did u say how many miles on the motor?

25,000 miles,it was just my summer cruiser

[95 imp]

Originally Posted by Kerry

In a way the front seal is kind of like a fuse letting you know their is a problem. very flimsily but adequate. Might even be a bad idea to replace it with the ls3 version.

I was just thinking the same thing. That seal blows as a warning vs. more engine damage.

[95 imp]

Well...

Not to be a PITA, but could we get a close-up of the crown? I tried blowing it up as much as I could, but still can't see it good enough.

I'm looking for pits or a "sand blasted" area. Also could be on the sides above the first ring groove. (still technically part of the combustion chamber)

That being said, .019 on the gap works out to bore X .047. This *might* be a problem on a forged alloy due to heat expansion. Hypereutectic pistons are less prone to expansion.

So, I'm still leaning against it being a ring issue.

The skirts are clean and the bore isn't damaged, so there wasn't a seizing issue.

The bearings show that there *might* be some detonation due to the wear in the center only.

A lean mixture will cause detonation.

"A lean air/fuel mixture will promote detonation, because a lesser quantity of fuel, when vaporised, will absorb less heat. Thus a lean mixture increases heat, the root cause of detonation. For this reason, you will usually find that supercharged vehicles will, if anything tend to run a slightly rich Air/fuel mixture."

http://progl.com/General/detonation....uel%20mixture.

[Kerry]

Their is no deto on that piston neither was their any on mine. Deto on a piston is easy to see it dont hide. With the tight tolerance's of the rod bearings 1.5 thou looks kina normal for these days oil. Run some 15w50 and those bearings wont look like that. They do look kina bad but they will run like that a long time. This thin oils are about gas or fleet mileage.

Also the bearings are way bigger on the sides than the top and bottom so u will see way more wear their, or what looks like wear. The reason they are bigger on the sides is to let the oil flow.

Their is another myth btw while Im at it. Thicker oil is for more clearance on bearings. The manual on the Camaro tells you can run 15w50 on the track if u want to. Still the 1.5. Why do they tell u to change it after the race. Cause its probly against their fleet gas mileage epa ect.

Since I seized the number 7 rod in my coop I will never put a light weight oil in my performance motor. After running the 15w50 and then having to go back in on my convertible to replace pistons from the broke ring land thats all I will use. Things looked much better. I even reused the rod bearings.

The bottom of the rod bearing looks wore too. but deto would only affect the push down top Bering closest to the piston.

[s346k]

exact same scenario. sbe blower motor.

same chain of events. cool weather rolled in, popped front seal and that was all she wrote.

6/8 pistons were damaged. bore looked perfect. there were pieces of the ring land in the lifter valley and oil pan both. rings hanging down inside the bore, under the piston.

detonation wasnt evident until we cleaned everything up.

[Crazy Drywall Guy]

Originally Posted by 95 imp

Well...

Not to be a PITA, but could we get a close-up of the crown? I tried blowing it up as much as I could, but still can't see it good enough.

I'm looking for pits or a "sand blasted" area. Also could be on the sides above the first ring groove. (still technically part of the combustion chamber)

That being said, .019 on the gap works out to bore X .047. This *might* be a problem on a forged alloy due to heat expansion. Hypereutectic pistons are less prone to expansion.

So, I'm still leaning against it being a ring issue.

The skirts are clean and the bore isn't damaged, so there wasn't a seizing issue.

The bearings show that there *might* be some detonation due to the wear in the center only.

A lean mixture will cause detonation.

"A lean air/fuel mixture will promote detonation, because a lesser quantity of fuel, when vaporised, will absorb less heat. Thus a lean mixture increases heat, the root cause of detonation. For this reason, you will usually find that supercharged vehicles will, if anything tend to run a slightly rich Air/fuel mixture."

http://progl.com/General/detonation....uel%20mixture.

Hopefully you can see these better,my phone camera isn't the best.

[Crazy Drywall Guy]

The picture with the red arrows if you look close you can see cracks where the ring groove/land was ready to let go. I think it held everything together long enough to get it home.

[95 imp]

Still hard to tell...

maybe @ 9:00 it looks rough???

It will look like it was sandblasted, or pocked. check the head too.
Also, you might have to clean them off for a better look.







These are still cast pistons and it isn't going to take much abuse to pop one, especially when they are overloaded with boost.

[Crazy Drywall Guy]

Originally Posted by 95 imp

Still hard to tell...

maybe @ 9:00 it looks rough???

It will look like it was sandblasted, or pocked. check the head too.
Also, you might have to clean them off for a better look.







These are still cast pistons and it isn't going to take much abuse to pop one, especially when they are overloaded with boost.

I cleaned it a little.

[95 imp]

Originally Posted by Kerry

....Also the bearings are way bigger on the sides than the top and bottom so u will see way more wear their, or what looks like wear. The reason they are bigger on the sides is to let the oil flow. ...

The bottom of the rod bearing looks wore too. but deto would only affect the push down top Bering closest to the piston.

If you take a bearing and set it on a bench with the open side up and tap the center with a ball peen hammer the edges will start curling in.

As they curl in, you change the clearance on the side because it is now egg shaped.

You can actually spin a bearing from deto because, if a bearing gets hammered enough, the edges can pinch in and cut your oil film off the bearing/journal and you lose the oil wedge.

Originally Posted by Kerry

Their is another myth btw while Im at it. Thicker oil is for more clearance on bearings. The manual on the Camaro tells you can run 15w50 on the track if u want to. Still the 1.5. Why do they tell u to change it after the race. Cause its probly against their fleet gas mileage epa ect.

I think that is correct. The thicker oil is harder to push out of the bearings, but your gas mileage drops. 10/40-20/40 was the recommended norm back in the day. High mileage used 20/50

No matter what the factory recommends, 5/30 wouldn't be the oil I'd use knowing the way I drive.

0/40 freaks me out and I always warm up the car by idling until the water gauge stats moving (or warmed up) then light load driving (under 2k/no more than 25% throttle/no downshifting) until the oil hits 175-180* so it thickens up.