This is a tough one...i have a 98 GT ...a while back i went thru a puddle while it was raining and sucked up some water...the car still starts and believe it or not idles fineee but theres a very loud noice comin from the engine.. tha sameee noise that you may make if your still moving and put your car into park with an automatic. It varies with the RPMs of the engine but only to a certain point then it stays at the same beats per minute, thats around 2200RPMs, anyways i pulled the valve covers cause i thought it was my heads...its not there perfect..theres no way i blew a valve ..and the bottom of the engine is stronger than the heads, its werid because the car doesnt run horrible when at idle it just makes a loudd!! noice. so im thinking that its a wrist pin..im gonna pull the block apart this weekend...any suggestions?? thanks

 

Could be alot of things. But normally when you hydrolock a motor youre gonna get a bent piston rod, wrist pin , or like you said bent valve. How do you know you didnt bend a valve... all you did was pull the valve cover. Good luck dude.