2002 S500 - Changed spark plugs, suddenly engine acts as if there is no oil pressure.
 

This is my buddy's car, I'm doing the work for him. So here are the dirty details. Before I performed this repair, the water pump pulley seized up and shredded the belt. Replaced both, and was fine for me, however the belt jumped off when my buddy started it. Put it back on and seemed fine from there, the plastic tensioner pulley had a rough surface so replaced it as well. Fast forward to the repair.

Replaced the Bosch platinums with NGK iridiums, they came pregapped at .044", however Alldata said to set them (Bosch or NGK) at 0.8mm or .032". So I set them all to .032". Install, and yes plug wires were correct, turn over, engine sounds like it has no compression, no attempt to fire. Compression tested great on all cylinders when I removed the old plugs. I theorize the plug gap could be the problem. Remove plugs, reset all of them to .044", reinstall, no codes on scanner, turn over, same thing. After turning over a few more times it eventually begins to sputter and now runs on its own. Only it makes a very obvious no oil pressure rattle from what sounds like lifters and timing chains. I let it warm up a little, no change, ran the rpms up to 3,000 a few times sharply and softly, no change. Oil level is full.

Also this car does not have a oil pressure gauge. I have a snap on ethos pro scanner, and it shows no oil pressure info in any of the data menus.

Interestingly, the first time it fired the belt jumped again, not sure why that keeps happening either. After that it stayed on. Figured I would throw that in as well.

So what the hell? Has anyone ran into this issue by chance? Could I be missing something stupid? What would be the best way to go about getting the oil pressure? I did not mess with or unplug anything electrical outside of the coils, and the fan assembly. Thanx in advance for any input.