PS. Past error codes are a good indication of what could be happening. Sorry, another reason to go to the dealer.B4 you yank the engine. should really do a compression test. It could be a cracked head, valves, rings, cyl,,,,,,. try to figure it out, with-out the engine running is a crap-shoot. The compression should be between 427-469, with less than 10% beween the cyls. Min.is 341. No tools? Should take a dealer around 1-2 hrs to do it. With the wet test. FYI the engine and hydros come out as a package, there mounted on the same frame. New engine $7000, Rem 5000.New head $1800.