Attention: TDR Forum Junkies 
During the winter, the engine started a metallic tapping sound that my neighbor noticed from across the street (I go to the hospital early and everyone hears my start-up). It seemed slower than engine RPM and I counted the taps for ten seconds (like checking a patient's pulse) and it was at half the engine RPM. This led me to believe it was related to valve train and I start thinking bent pushrod and mostly drove my son's car as he is away at school. When I did drive the truck, I babied it and it got no worse. Funny thing, the tapping faded out at around 2200 RPM.
I put a stethoscope to the valve cover bolts and it seemed loudest at #4 so I pulled the cover and the pushrods were OK but the exhaust rocker seemed a little loose. I figured it needed a valve adjustment which I did a couple of weeks ago. Surprisingly, they were all pretty close to start with and I set them at . 09 intake and . 19 exhaust on a cold engine. Fired it up and still tapping just like before.
Last week, on startup, the tapping was replaced by a . 50 cal machine gun sound that didn't fade out at any RPM. I drove it to my mechanic and he came out as I drove up with a WTF? look on his face. He and several of his mechanics listened with the hood up and the booming seemed to come from the intake side, although I was thinking exhaust manifold (mainly because i still have the stock one and want to put on a three piece one with a bigger turbo).
Anyway, I left it with him as I was headed out of town. Today I get a message that he thinks it is a bent valve; does this sound right?
I'll call him tomorrow to see how he diagnosed that, but I want to be sure before I have him pull the head. Anyone else have something similar happen? Any help would be appreciated.
I put a stethoscope to the valve cover bolts and it seemed loudest at #4 so I pulled the cover and the pushrods were OK but the exhaust rocker seemed a little loose. I figured it needed a valve adjustment which I did a couple of weeks ago. Surprisingly, they were all pretty close to start with and I set them at . 09 intake and . 19 exhaust on a cold engine. Fired it up and still tapping just like before.
Last week, on startup, the tapping was replaced by a . 50 cal machine gun sound that didn't fade out at any RPM. I drove it to my mechanic and he came out as I drove up with a WTF? look on his face. He and several of his mechanics listened with the hood up and the booming seemed to come from the intake side, although I was thinking exhaust manifold (mainly because i still have the stock one and want to put on a three piece one with a bigger turbo).
Anyway, I left it with him as I was headed out of town. Today I get a message that he thinks it is a bent valve; does this sound right?
I'll call him tomorrow to see how he diagnosed that, but I want to be sure before I have him pull the head. Anyone else have something similar happen? Any help would be appreciated.
