The lock up could either be at the valves or rings. I have seen those multi piece oil rings get messed up during install and then getting jammed between the piston and cylinder jamming up the works. Starting a new engine and just letting it idle is not a good thing. You need to rev it a bit and get the oil flying everywhere. It takes some splash and spray to get it hitting the pistons at the top of the stroke to get the cylinders oiled and get the valve stems lubricated.  It is also possible that a bearing locked up and spun. It is also a good idea to monitor oil pressure after an overhaul. 

Fluke or not there was a cause and defective parts and mistakes do happen.  Before pulling the engine I would pull the rockers and make sure it is not just a seized valve. If the heads were rebuilt with new guides it is possible the guides were not reamed properly after being pressed in the head and a valve seized up. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of John Rodgers
Sent: Friday, March 18, 2016 7:02 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Carat

Without bad luck, I would have no luck at all!

Yesterday the engine  back in my Carat. Today the engine was run and it was beautiful. Sounded so good. While idling to allow to warm up and begin the break-in, it stopped suddenly, never to start again. In fact, never even to be turned by hand with a wrench  - seized solid. The rebuilder is flabbergasyed. I'm flabbergasted. He said in all his years on rebuilding VW engines 'he never had  a Vanagon engine do that. Two aircooled ones but never a 2.1 L WBX. Anyhow,  come Monday, out it comes for a tear down again.  I've a choice: take one of his other rebuilts, or wait for this one. What would you do? There are six to chose from. Jim is an excellent mechanic, and I think this is a fluke!

And, anyone want to speculate on the cause of this one locking up?

John