Well I'm halfway thorough my engine swap on my QX56.

It's time to do some diagnostics on the replacement engine.

I purchased it from a junk yard for $1600 (shipped from CA to UT) with a 90 day warranty. Supposedly came out of an armada that was rear ended.

The engine has 70k miles on it.

What kind of tests should I run on it? What should I replace off the get go? I am torn between "change it while the engine is out - do it right or pay the consequences later" and "don't touch anything - it's a relatively young engine and if something breaks take advantage of the warranty, plus I don't want to spend more money than absolutely necessary, plus I need this up and running ASAP."

A Compression test, general inspection of the accessory pulleys, and a rear main seal seem like common sense. I'll take a peek down the intake ports and up the exhaust ports. Turn the crank by hand to make sure it turns and I don't hear anything weird. Oil pan is hard enough to get to that it would probably be worth my time to reseal it while the engine is out.

I figure if it turns out that the valve covers leak I can get to those easy enough from the engine bay. I thought about doing the timing chain but it is kind of a pain to do, though frankly if I have the engine out like this, and if I'm pulling the oil pan anyways, it really isn't that much more work I guess.

What am I missing?