I have an LQ4 on an engine stand - I found a little bit of water in the oil pan, and I want to make sure there are no coolant leaks/cracked block/etc.

Has anyone done this before?

I plan to cap all of the water pump ports, and apply about 5 psi to the block system - let it sit, and then see if there was a pressure loss.

 

Should work, just make sure the temp is consistent throughout the test. I'd be inclined to go to higher than 5# though, maybe even 20#, which would simulate 260°F...

 

+1 try 20 psi.

 

Won't be a valid test unless you can heat cycle it while under pressure but it may find something. If its a aluminum block its going to grow a bunch hot.