Atomic 4 and muffler

Feb 25, 2014
95
Catalina 30 Grand Lake. Wyandotte, Ok.
So I have a 1977 Cat 30 with the Atomic 4 engine. This is one that has the problem of water coming back into the engine from the muffler when cranking too long. Fix... Shut intake off till engine starts.

Why does this happen and is there a fix?
Is this common to Atomic 4's on other boats?
Would a new style muffler or other means fix this issue?

Would like to hear thoughts about this setup and topic.
 
Aug 28, 2006
493
Bavaria 35E seattle
I had an A4 without that issue. I don't believe it is common. You should contact Moyer marine or visit the forum at moyermarine.com/forum and post for other A4 owner's input.
 
Jul 6, 2013
172
Catalina 30TR, Atomic 4 2480 Milwaukee
So I have a 1977 Cat 30 with the Atomic 4 engine. This is one that has the problem of water coming back into the engine from the muffler when cranking too long. Fix... Shut intake off till engine starts.

Why does this happen and is there a fix?
Is this common to Atomic 4's on other boats?
Would a new style muffler or other means fix this issue?

Would like to hear thoughts about this setup and topic.
I have a 1982 vintage A4. I don’t have this problem, but I’ve heard of it before.
The issue is that when you’re cranking, the water pump is running, filling up the muffler, but there’s no exhaust pressure to push it out. When the muffler gets full, water backs up into the engine, especially the #4 cylinder.
One solution would be what you’re already doing, shut off the intake while you’re cranking.
Better would be to get the engine tuned up so it starts easily. Go through the whole ignition and fuel systems. Mine usually starts on the first try, even coming out of winter storage.
Or you could convert to a closed cooling system, but that would cost hundreds of dollars.

As nightowie says, Moyer is a great resource.
 
Jan 4, 2006
3,899
Hunter 310 West Vancouver, B.C.
Every marine engine has this problem if you crank too long.

You keep pumping water into the muffler but don't have the large volume of exhaust gasses to expel the water out the wet exhaust hose.

Sure, you can install drain hoses here and there and risk CO poisoning if you value your engine more than your life, and many serious boaters do :p.

Best solution is to close the raw water valve if you're having a problem with starting and remember to open it once the engine catches. No problem remembering that :facepalm: for sure.
 
Feb 26, 2004
21,949
Catalina 34 224 Maple Bay, BC, Canada
It might also help if you are condering WHY this happens, as Ralph says, to all inboard engines below the waterline. The attached explains it. Of course, getting your engine to start sooner is really why you should read Moyer's website, because the muffler thing is not a Moyer A4 issue at all. Good luck.
 

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