big plumes of the blue stuff coming out the exhaust. Any ideas where it is coming from? Here's the clues:

1. Motor is pretty new.
2. 355, vortec heads, 10:1 compression, decked , align honed, comp cams extreme marine, etc., etc.
3. Oil pressure is very high, around 60 psi as read on the dash gauge.
4. Oil burning takes a while before it starts The motor has to be running until it's hot - maybe 10-15 minutes. Even so, if hot, then left off for a little while, it won't burn oil for a little while.
5. I had an intake lifter fail (cylinder 8). It's been replaced, even though the cam is somewhat worn on that lobe
6. Motor runs strong and smooth.
7. The motor is very new in terms of miles - maybe a few hundred miles tops. But, the engine is probably a couple of years old at this point

Yep, I know it could be the rings - but I'm hoping it's not. I was really carefull when installing them It could be the valve seals - and I'm thinking this is the likely place to look next. The heads are using the vortec stock valve seals. Do they have a history of failing? There wasn't much t them. I'm thinking about changing over to something better.

Any thoughts?

 

Compression and leakdown tests.

 

I doubt its valve seals, since it only does it after it gets warm.
I'm leery about guessing rings as well.

Pull the plugs, and see if certain plugs are clean, and certain ones are oil soaked. I'm guessing it's burning oil only on certain cylinders.

I'm putting my guesses onto an intake manifold leak (after it gets warm and everything grows at a different rate), or having to do with your one semi-wiped lobe. I'm not sure how having a wiped lobe could do it, but it can cause some strange happenings.

 

I also thought it might be the intake gasket. Those vortec intake gaskets are O-ringed, and I think, reusable. When swapping out the failed lifter, the gasket looked pretty good, so I reused it. There's a spec for how tight it needs to be, and it's very low (15 ft-lbs or so).

One thing that worries me is that the lifter had significant damage. It was worn clean through to the guts. The internals are clearly visible from the botton of it. That's a whole lot of metal floating around the motor! Depending on how large the fragments were, they do drop down into the crank case. Suppose a big chunk landed on the cylinder walls and scored up the bore or the piston? I'm not sure, but I think the oil burning would be continuous under that scenario.

I need to pull the plugs and see if I can isolate a cylinder. Not really looking forward to that. The plugs are a bear to remove on the vortec heads with headers.

 

You chewed up a lifter (assuming flat tappet), replaced it but not the cam.

To start off with, you've circulated iron filings throughout your engine. Plus, you're creating more by putting a new lifter on a hurt lobe.

You'll be pulling the engine apart soon. This time clean it thoroughly, and break in the cam properly.

 

Wow, that was harsh - not wrong, but harsh. Although you're not giving any idea of what may be causing the oil burn, I think you 're implying the metal shavings have damaged something - which is likely.

As for the cam - I was being lazy. For $5 and a couple of hours work, I got to see if the engine oil burning was due to the valve remaining closed all the time. Maybe this is going out on a limb, but the theory was that the intake lifter went bad, so the intake never opens. On the intake cycle, a vacuum develops in the chamber, which might suck oil up past the rings - maybe.

Replacing the lifter did nothing for the oil burn but the motor is running very nicely - albeit with a degraded intake lobe on cylinder 8.

 

No intent to be harsh, just honest and to the point.

Have you pulled the plugs yet?