It's like a compression test. You screw a hose into the spark plug hole. Instead of turning it over to cause compression, you force compressed air into the cylinder via an air compressor.
It has two gauges:
1) Pressure of the air coming in.
2) Pressure of the air in the cylinder.

You can buy this tool at most auto stores, possibly harbor freight / ebay.

The % difference is the value of leakdown. Cylinders aren't perfectly air tight, the rings have small gaps. It's a good gauge of how well your rings are sealed. If your vavles are leaking you'll hear air coming out of the exhaust (or intake) ports.

You might look up normal leakdown, but I think it's in the 5-10% range.

The best I've ever seen is 2-3% with "total seal" rings.

The leak down test will also expose head gasket leaks. If you hear a bubbling in the radiator, pressure is leaking into the radiator. I suppose the same thing could happen on the oil side also...

 

The oil consumption is either burned after passing by the rings or valve seals/guides or leaking into the water or leaking onto the pavement.

That much oil consumption is bad. If the rebuilder put chrome rings in the motor, good luck getting them to seat. I always use the cheap iron faced rings from Hastings. They seat quick even in marginal cylinders that have only been honed. Hope the rebuilder put new valve stem seals on during the head job. Maybe the seals are missing....easy to forget if you had a few Buds during lunch!

The plugs should show oil burning. If not, its in the water or on the ground.
Keep Looking.

 

Right on, thanks. Oil is diffently not in the water, thank God! Had the the head redone with new valve guides and seated properly. This problem is really frustrating. Before hand I a problem overheating, fixed that problem, now this. Oh well I guess things will work out.

 

Good news y'all. For what ever reason my truck quit burning oil. Really wierd but I am not complaining.

 

Now isn't that something.

 

Sounds like the rings finally decided to seat.