I recently bought a Mariner 40 hp fourstroke from year 2000. It's been sitting for about 5 years due to the death of the previous owner. I do not beleive the motor was winterized before this storage.
The carbs seemed to be the obvious problem since there's a lot of fuel crystals in bowls and jets. Full rebuild will be made.
The engine goes around very easy by hand when plugs are removed but when I put my finger over the plug hole I only feel compression on cylinder 1 (top) and 3 (bottom). On the middle cylinder I don't feel a thing.
The seller, who knew the previous owner, was very sure of that the motor was working when it got stored away so I don't think it's at burnt piston/cylinder. My previous knowledge is only from twostrokes but I think that you often feel or hear if a piston/rings/cylinder is the problem and you often get a little feeling of the compression.
Without having yet removed the valve cover my guess is on a stuck inlet or exhaust valve. It's not that open that you can hear the piston hitting it, but I don't even know if they open that much. I guess that when I remove the valve cover it's pretty easy to see if the valves are following the cam/rockers.
Does anybody has any ideas of what to check for? Is there anything else that has to be overhauled? I'm changing the impeller and timing belt and of course engine oil and gearcase oil.
Kryck
The carbs seemed to be the obvious problem since there's a lot of fuel crystals in bowls and jets. Full rebuild will be made.
The engine goes around very easy by hand when plugs are removed but when I put my finger over the plug hole I only feel compression on cylinder 1 (top) and 3 (bottom). On the middle cylinder I don't feel a thing.
The seller, who knew the previous owner, was very sure of that the motor was working when it got stored away so I don't think it's at burnt piston/cylinder. My previous knowledge is only from twostrokes but I think that you often feel or hear if a piston/rings/cylinder is the problem and you often get a little feeling of the compression.
Without having yet removed the valve cover my guess is on a stuck inlet or exhaust valve. It's not that open that you can hear the piston hitting it, but I don't even know if they open that much. I guess that when I remove the valve cover it's pretty easy to see if the valves are following the cam/rockers.
Does anybody has any ideas of what to check for? Is there anything else that has to be overhauled? I'm changing the impeller and timing belt and of course engine oil and gearcase oil.
Kryck
