I have a 97 460 that has had a pinging issue. I have tried seafoam in the intake, retarding the advance, but nothing seem to take care of the problem. no engine codes at all. I did a compression test yesterday, (truck running smoothly) and found all cylinders were between 160 - 175 psi, except #3 which only had 125. So I know I have a problem there. I have since removed the intake manifold and am about to pull the head. The intake gasket all looks good, no visible leaks. There is a lot of wet gas/oil residue in the upper intake. Any thoughts on what is going on iside this motor? It currently has 77K on it. Thanks

 

with pinging and small compression differences in some cylinders and one with a big difference that cylinder probably has burn valve a leak down test is the best way to diagnose the cause or a cap full of oil in the plug hole of the low cylinder if it don't raise the compression it's in the top end

 

It looks like you are already too far disassembled for any meaningful test. I'd keep going. Get that head off, and let it tell you its story.

I think that no matter what the problem is, with that kind of compression difference, the head has to come off to fix it.

 

Super ford, Was everthing set to factory specs?I have a 97 the same as yours that runs fine.After you get the compression fixed,check EVERY vacuum hose and connection.If you spray ether at anything suspicious, the engine will pick up speed if there is a leak.The intake oiling could be the PCV valve or blowby,also check the piston tops for evidence of detonation,mabey you can isolate which cylinder(s) are the problem.Good luck. ragingpinto