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Hello all, I just picked up a beautiful 75 f250 with a 390, very stock. After driving it around for 2 weeks it started running like junk. Pulled the plugs and one is wet. Can’t tell if slight oil film on it or fuel. Then I did a compression test on all cylinders and the said cylinder gave me a reading of absolute 0. I stuck a tiny flash light in the cylinder and it looked alright but I did not see everything.

What is not the next few steps I should take to find the problem? Will I be able to tell if my valves are messed up by pulling the valve covers?
 

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*what is the next step in the trouble shooting process? Also it’s on the 3rd cylinder looking at the engine from the front of the truck on the passenger side.
 

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Do a wet compression test on that cylinder. Squirt about an ounce of your regular engine oil into the spark plug hole then immediately do the test. The oil will seal the ring. If you still have 0 compression that points to a stuck valve.

I'll go out on a limb and take a wild guess that you bent a pushrod, because I bent several myself on my 390 about three years ago. I made the mistake of trying to burn off old gas left in the tank. The 10% alcohol in the fuel had basically turned into shellac, causing several valves to stick, and the weak link was the pushrod.

If that's the case, pull the intake and heads and have them disassembled and cleaned. New pushrods, new gas tank, flush out the fuel lines with brake-klean, and you should be on the road in no time.
 
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