No compression

[irtrimble]

Engine won’t start after three years out of water(couldn’t get to Canada due to covid). Mechanic says poor compression. Stuck valves or rings. Can valves be accessed to free them by removing manifold? Right now engine sitting over weekend with oil in cylinders.

[Dave Neptune]

If the engine turns the rings are probably OK. The valves can be accessed once the cover plate is removed and it is easier with the manifold removed.

Dave Neptune

[tenders]

It is also possible to work the valves a little bit with an Allen wrench through the spark plug holes. The valves are off to the side of the head, not under the spark plugs, so this takes a bit of finesse.

If the engine was running OK previously, I'd give this a shot - a few manual cycles might free them up enough to get the engine to start.

[sastanley]

All good suggestions above..I'd also try squirting something like Marvel Mystery Oil or something else with lubricating properties into the plug holes in the direction of the valve guides..they are probably sticking and locking the valves in place.