Lost compression

Hi,

That is odd, I agree. Do me a favor. Pull a couple of plugs and see if the pistons are even moving. This doesn't make sense. I'm questioning if the crank broke. All of the cams wouldn't have broken at the same time. Also, have you pulled the valve covers to see if the cams are turning?

Let me know.

Joe

Strange, I would almost suspect the gauge as faulty. Do you have another to try? When doing the compression test, the front accessories were turning? If yes it's not a bad crank.
Maybe pull the valve out of the compression tester and use that hose with a compressor to try dumping air into a couple cylinders and see where it comes out.

Well that is different. Timing marks were okay and both cams were moving? I could see an engine losing 1 or 2 cylinders if it broke a rod but losing all 8 is a strange one. Got a borescope you could check the pistons with?

Borescope in a plug hole would be the fastest as it would show movement and condition of the pistons, just don't use the starter to turn it over. If the crank and cams are moving then yes the pistons should be moving, but if you have no compression in any cylinder then either one valve in every cylinder is open, which would be impossible, or there is another reason. Even if you removed every piston ring you should get some reading. So either the pistons are not moving or something else is very wrong.

On item I forgot about, do you have the air inlet on the intake apart so you're sure air is getting through to the engine? I know some of the Fords had an issue with the air intake sucking in a chunk of the isolator foam in the fender well. If no air was getting in you would have very low to no compression. Odd idea but?

Just checking to see if you had any updates or found the problem?