kelsey_canard

iTrader: (6)

Car has smoked since I bought it. Blue oil smoke at WOT. . It has since gotten worse. I'll see if i can get a video later, but it is definitely worse.

Setup is a 5.3, torquer v2, 750 holley. This week I installed new valve seals, rejetted the carb, seafoamed the intake and crankcase. Valve covers have breathers, so the crankcase is just vented. Did a compression test and all cylinders were right on with one being about 15lbs down. Noticed no abnormal sounds when using air to hold up the valves while changing seals. Car actually set a pb yesterday, but is smoking way worse. Doesn't use a drop of coolant.

I don't feel like the thing is down on power, or substantially down on power. It is running a 8.20 1/8 @ 3600lbs. Which seems about right for 3.42 gears and shorty headers at that weight.

Has anyone ever seen a cracked ring land just take out the oil ring, but compression still be fine? Any other ideas? I'm 95% sure the previous owner had nitrous on this. Id hate to pull the thing apart with it running fine, but the smoking is aggrevating me to death.

conan

iTrader: (5)

I pulled the LM7 out of my dads 01 Yukon XL for a failing oil pump at 219,xxx miles a few years ago. It would burn about 1-1.5 QT's of oil every 3,000 miles. Ended up pulling the entire engine down since it was out of the truck and found 6 out of 8 pistons had the oil scraper rings were stuck in the lands and had no tension to them. We replace all the rings and put a light hone on the cylinders and reused everything else bearings and all. Just changed the oil last week and she now has 347,xxx miles on the clock and doesn't even use a half QT of oil in between its 4,000 mile oil changes.

You have no PCV returning to the intake manifold ? Just vented rocker covers ?

Congrats on the new PB by the way.

kelsey_canard

iTrader: (6)

Here's a video from the weekend. I did run a half a can of seafoam through the intake the night before, but it probably had 30-45 minutes of run time. Smoked all day reguardless. Seems to start at 5500rpms + https://www.youtube.com/watch?v=n03S...ature=youtu.be

Pcv on both valve covers is ran to a breather. nothing in the intake. Had the carb off the other day and the intake looked perfect.

Taxman20

iTrader: (11)

Ok, since you do not have PCV valves hooked up to pull vacuum on the crankcase, you are most likely building pressure inside the block which is pushing oil past the rings on 1 or more cylinders.

kelsey_canard

iTrader: (6)

The crankcase has breathers on it.

Taxman20

iTrader: (11)

Doesn't matter. The crankcase should be under a constant negative pressure. This is one of a couple reasons we run vacuum pumps on our drag engines.

kelsey_canard

iTrader: (6)

I agree that is optimal, but stock engines do not have a vacuum at wot using a pcv setup. Most **** does fine with breathers. Every time i see excessive crankcase pressure it will blow a seal out. Valve cover, rear main, etc...

Taxman20

iTrader: (11)

First we can break it down.
Valve guide seals will leak all the time if bad, you only leak at high rpm.
No pcv system so your not sucking oil into the intake.
Only thing left is the oil rings. Low rpm no issues that you know of. If theres any blow by at all on any piston, its going to build more crankcase pressure as the rpm rises. This pressure can only escape so fast. If its building faster than it is escaping, then its most likely pushing some oil past some rings. You have a combination of positive pressure in the block pushing on the bottom on the piston combined with the suction of the cylinder on the intake stroke. This increased negative pressure is in the cylinder due to the piston trying to suck air faster past the intake valve. The presure isnt seen in the intake because the intake has the larger TB opening. The intake always has vacuum in it, just not as much. It nevers goes to zero.

You never stated the mileage on it. My money is on the rings. Maybe just a good glazed cylinder too.

The only other thing it might be, and I have seen this happen but rarely. You may only see this on the strip at high rpm. You MIGHT have a head not draining oil fast enough which is pooling oil in the back end of the head which might have the level high enough to basically flood that back valve guide and let oil past the seal.

Darth_V8r

iTrader: (4)

OP, I'm gonna piggy back off Conan here. The one cylinder that's low, if you squirt a spoonful of oil into the cylinder and recheck, does it improve? If yes, then that cylinder rings are the culprit.

VandykeT/A

I've got a 408 with no pcv breathers on both valve covers. One big one over the oil cap and one in the rear on the driver side small that I made from cutting the bottom off a pcv valve and clamping a small filter to. I turn that motor 7200 and running 10.50s and it smokes none. I'm gonna bet on rings.