Atomic four self destruct

[Garry D]

I was stuck on a sand bar. Was using full power on my atomic four. It started spitting steam out the exhaust, heard a snap, and engine quit. Went below oil smoke coming out of the oil fill cap.Tried to restart, and it started, but loud clunking was heard. Forward to today, thinking i broke a rod or piston. Using a camera, checked piston heads through spark plug hole. All pistons went up and down without issue or noise. Piston heads look steam cleaned, wish I could post pictures but cant figure it out. So im sure i either cracked the head, or blew a head gasket. But the metallic clunking noise is a mystery. Anyone have any ideas. Its being removed in the spring for repair and replace. Spun a bearing possibly

[zellerj]

When stuck on a sand bar with my stern facing boat traffic a large wake hit my stern and pushed water up my exhaust hose, filling the water lift muffler, and water got into my cylinders. I then found water in the oil. After a few oil changes all was well. Whether a wake or waves, slapping against the stern can lead to issues. Could have this type of scenario happened to you?

[ndutton]

A spun bearing should result in zero oil pressure (do you have a working gauge?) and give a sickening engine knock. A compression test and a water jacket pressure test would provide a lot of information.

[Dave Neptune]

If a rod was broke that piston would not go down but could go up but stay up if the rod was broken at the wrist pin. As all four pistons are clean the water probably came in somewhere other that the head gasket. If the loud crack noise was metallic in nature the crank could of broke. Sometimes depending on where a crank breaks both "ends" can still rotate and even allow the engine to run a bit. However on a two bearing crank like the A-4 it is unlikely but still possible. I have seen more than a few V-8's run with a broken crank.
Hopefully it is a spun bearing but either way the engine will need to be torn down.

Good luck.

Dave Neptune

[Garry D]

A spun bearing should result in zero oil pressure (do you have a working gauge?) and give a sickening engine knock. A compression test and a water jacket pressure test would provide a lot of information.

Well the oil smoke coming out of the breather cap made me figure I lost oil pressure. A spun bearing seems the likely problem. Just bought a replacement crank and rods. For spring. No time to check oil pressure it stalled immediately.It did restart but like you said sickening knock. Thanks for your response

[Garry D]

When stuck on a sand bar with my stern facing boat traffic a large wake hit my stern and pushed water up my exhaust hose, filling the water lift muffler, and water got into my cylinders. I then found water in the oil. After a few oil changes all was well. Whether a wake or waves, slapping against the stern can lead to issues. Could have this type of scenario happened to you?

Been there done that twice. Marina was the last culprit. Told them not to just sit and crank on it. Didnt tell me, and it had water in the oil. I put a flapper on my exhaust outlet in the spring. Thanks for responding

[Garry D]

If a rod was broke that piston would not go down but could go up but stay up if the rod was broken at the wrist pin. As all four pistons are clean the water probably came in somewhere other that the head gasket. If the loud crack noise was metallic in nature the crank could of broke. Sometimes depending on where a crank breaks both "ends" can still rotate and even allow the engine to run a bit. However on a two bearing crank like the A-4 it is unlikely but still possible. I have seen more than a few V-8's run with a broken crank.
Hopefully it is a spun bearing but either way the engine will need to be torn down.

Good luck.

Dave Neptune

Thanks for responding Dave think a rebuild is in order for the spring. I was supprised when all the pistons moved. Bought a good crank and rods for the machine shop to redo