I bought my first car/corvette last year and 3 weeks later motor blew. over the course of the next 6 months my boss helped me rebuild it (im an apprentice at a shop). Now i have about 5000 miles on the engine and burn about a qt of oil a week/150ish miles. On compression test all cylinders where reading about 180. did leak down test and had 4% leak down. we found no baffles on 9 bolt valve covers and thought that might be part of the problem but could not locate any with baffles. currently running ls6 valley pan and catch can set up which i just installed (have been running catch can on old pcv setup as well) and still burning an un godly amount of oil. Just wanted to see if anyone has any thoughts before i pull my engine back out and put new rings in.
Thanks in Advance

 

Take the car out have somebody follow you. If u have bad rings when you decelerate u should se blue smoke. That's the first sign off bad rings. Don't take it out of gear when decelerating. If there is no smoke your rings are good. That is a ton of oil. Is the catch can full.??

 

No, catch can is empty. i have blue smoke on accel and what appears to be white smoke that smells like oil come into my cab via sketchy welded straight pipes on decel.

 

When you did the compression test did you notice any excess carbon on one of the plugs?

 

If the oil is coming through the valve stem guides, you may get really good compression numbers and still be burning oil. In fact my C1 (2 x 4 bbl/283 ci) burned blue smoke on acceleration. Kept replacing rings, valve guides etc., until just by coincidence I checked valve seals:5 out of 8 cylinders had them installed wrong! HTH.

 

yeah on 1,2,4,6,8. Why?

 

blue smoke + soot or oil on plugs shows not just the bad cylinders but IMHO is a strong indication oil is coming from the intake valves

 

When u first start from sitting over night does it smoke ?? If it was bad seals that's the first indication of bad seal. Runs down the stem and puddles on the piston. JMO
what I wrote is moot. Didn't that it burns oil when driving. Time to do some work. Like taking apart engine. Starting with valve train like what was sad already. Start with the easy stuff first before tearing into engine.

 

I agree. Usually if you decelerate it creates a vacuum in the intake tract. Questionable valveguide seals will usually manifest themselves then, with a bluish white smoke. I once had an IROC-Z with a traditional 350 SBC. The old SBC had far from optimal guide seals. After working on the A/C with the car idling for quite awhile, I smelled oil burning. Since I'd been under the hood, I didn't see the smoke coming out the pipes. It was considerable!! A couple weeks later, my cat converter plugged, discovered when car wouldn't go over 45mph. Your leakdown test result of 4% is pretty good. However, a quart of oil in 150miles......My old 2 stroke snowmobiles used less oil than that, and that's a fact!!! This much oil would seem more likely to be rings than guide seals. I don't know just what you and your boss rebuilt-BUT......If you installed new piston rings, it almost sounds like they're in upside down. Rule of thumb on ring install is the numbers/markings always go on the piston facing up. OR-Could you have installed standard rings on a .010" oversize piston, in a .010" overbore? Without more info, these are all guesses......

 

After not seeing any more info, I thought this over more thoroughly. With a 4% leakdown, it would seem that the rings must be OK, or leakdown would be worse. Still, it's hard to imagine bad guide seals would cause 150 mile/quart oil consumption. I suppose it's possible. I once ran low tension oil rings, and got only 700 miles/quart, but that's far from 150 miles/quart!!! Check valveguide seals out thoroughly. Best of luck.....

 

Thank you for all the help, will be trying valve seals this weekend or monday. I will report back with results. Hopefully i do not have to take my engine back out lol

 

Cooked rings ...