Exhaust elbow blew up/engine won't start

[Rick]

Yesterday we found that our exhaust elbow leading from our Atomic 4 (gas) to the water lift was corroded beyond use when it blew up and started spraying water into the engine compartment. We turned the engine off and then restarted it. The engine started fine but the water was spraying out of a quarter sized hole. We immediatly stopped the enginge and wrapped a rag and duct tape around it so we could get back to the mooring. Needless to say, the engine now would not start. Today will be spent locating fixit supplies for the pipe. Does anyone have any ideas why the engine wouldn't start? My main concern is that water has a way to back into the engine. Please allay my fear of a rebuild.Any ideas?

 

[John Buckham]

A-4 Exhaust

On the A-4 the exhaust manifold is water-cooled. There should be no water coming from the exhaust port of the engine. If there is water coming out of the exhaust port you have real problems.Water is fed into the “front” of the manifold, flows through a water jacket, then out the “back” through a vented loop and into the water lift muffler. Sometimes the manifold will corrode through and water will mix with the exhaust, running back into the engine and causing serious damage. Hopefully the water is squirting out of the muffler, without pressure from the engine exhaust the muffler will fill up, rather than expelling the engine cooling water from the muffler and dumping it overboard along with the exhaust.The best source for A-4 parts and knowledge is Moyer MarineHTTP://www.moyermarine.com.Good Luck!John

 

[Rick]

Thanks

Thanks John, I didn't mean to say that water was coming out of the engine exhaust manifold. The water seems to be coming back up the exhaust pipe from the muffler and spraying out the exhaust pipe at the break.

 

[John Buckham]

Gas/Spark/Compression = Varoom

Thank goodness. With out exhaust pressure the muffler will fill up to the point the water will back up into the engine. If you are having a starting problem the water can be drained out of the water-lift muffler through a drain in the bottom while you trouble shoot the problem.I’ll bet with all that water gushing around the ignition system got wet.To make the engine run you must first have fuel, pull the choke on crank the engine for 15-20 seconds, this will flood it, pull a plug, it should be wet and smell like gas.Check for spark, re-insert that plug you just pulled and attach the wire to a second loose Plug and lay the plug atop the engine so the plug grounds to the block. Have someone crank the engine. Look for sparks.Compression? Pull that plug and put your thumb over the plug hole and crank the engine, your thumb should be blown off the plug hole from the pressure.Make certain the plug wire is well away from the plug hole (and your hand) before youCrank the engine. Also…the gas the come out the engine through the plug hole is explosive because it’s mixed with gas (like DUH?!) and if ignited can ruin your whole day, or week…Quick check hints…..John.

 

[Rick]

Whew! Thanks again...

Thanks, Now just one more silly question before I try it. Is the muffler drain an easy to find item? I do not have a diagram and am not on the boat, i also don't remember seeing anything like a drain plug on the muffler box...

 

[Jeff Walker]

Look under the sink

Rick,I don't have the Atomic 4 engine but my aqua-lift muffler drain is a small pipe with a cap on it that can be found through the access door on the floor in the kitchen. Look to the left and unscrew the cap to let excess water out. My instructions say to drain the muffler anytime the engine cranks for more than 30 seconds and does not start.Good luck,Jeff