Please Jesus tell me it isn't rod knock

dont let a mechanic friend that does not know these cars touch it... see if anyone on 3sgto near you that knows these cars willing to check it out. i would remove the oil pan and check each rod for peace of mine.

+1 its very easy to check for rod knock, just drop the oil pan and wiggle every rod.

i dropped a washer down my intake plenum but didnt realize it. i started my stealth up and it knocked like crazy. but all i did was pull my front head, use a pair of vice grips to pull the washer off the piston (was lodged in the piston and looked like a small pretzel) and then i put the head back on. that was around 20,000-25,000 miles ago and she still runs fine. my dad daily drives the stealth every day to and from work. so even if you did drop a washer down the plenum theres a good chance it will only cost you ~$100 for new head gasket and bolts.

I was lucky and was able to pull the washer out of the spark plug hole in a buddy's car...which is why I asked if there were any closed up plugs. Usually the washer will damage the plug as it bounces around in there, but sometimes not.

Rod knock doesnt come out of nowhere. It develops over time. Since you ADMIT to not covering the intake when the plenum was off, you have solved the mystery. NEVER EVER leave anything open when you do disassembly.

Yes I have personal experience with this sort of noise in a Kia engine that grenaded. I typically leave the intake in the car when the engine is removed. Unfortunately, a piece of steel from the old engine got sucked out of the intake into the new engine and started making a racket. Luckily it wasnt very big and didnt make any holes.

If you are lucky there will be no bent valves. If not head work will be in your future.

You can also remove the oil pan and look for evidence. You will find LOTS of glitter in the oil if it really is rod knock. You can also move the offending rod(s) if the bearings are damaged.

Good luck in your repairs.

-SP