Atomic 4 runs, stops and then starts up~stops again~I'm stumped.

[Herron]

Don~

To refresh your memory. We chatted a few days ago regarding an issue with my Atomic 4 which starts immediately, runs beautifully for about 1-2 minutes then fades and stops with a bit of stress, almost as if it was about to seize. Amazingly, she will start immediately and repeat the same process. I have no history on the engine and boat (Catalina 27) as I acquired it from a local Rockport Maine YMCA auction in the summer of 2006. Over the winter (2006-2007) I removed the engine from the boat and together with a friend we replaced the exhaust manifold (which had a crack). The block and cylinders looked amazingly clean with very little wear. The valves were ground and seated, the tappets cleaned and adjusted, thoroughly cleaned the water ways and replaced all gaskets. The carburetor was cleaned but we did not replace any parts. New plugs, wires, rotor, condenser, coil, hoses, exhaust pipe. Most all essential parts were either cleaned and or replaced.

The compression is at or above 100psi on all four cylinders. Oil pressure indicated is about 40-45 lbs and is level and consistent. I've removed the screen from the gas tank (which was very clean) and have a fuel filter in line. The timing is right on the money. When started, the engine runs superbly and when given the throttle-up she revs up perfectly. Then she slows down (as is a load was on the engine) and stops. There is a little oil smoke too. But as mentioned, she cranks up again immediately without issue. We've checked the neutral position to make sure she is running freely each time (boat is on stands in my home driveway). Uggh! We are really stumped. What could it be?

[Don Moyer]

Herron,

If I recall correctly, you were going to see if the prop shaft might be
trying to turn after a minute or so. Did you check that possibility?

Don

[Herron]

Follow-up

Thanks Don~

Yes, we did check and have made sure the prop is free. It does not seem to have an affect.
Also, while the engine starts immediately following stopping, each time it will run for a shorting period of time unless it is given about 1-2 minutes to "kind of" recover.

Ideas?

~James

[jhwelch]

Sounds like you may have a fuel flow issue -- when idling enough gas
is getting to the engine but when you run the motor faster not quite
enough makes it and in a minute the fuel in the carb. bowl is drained
and the motor slows down and quits.

Take your carb. off and apart and see if the float may be sticking, if
there is any grit in the bowl, or if anything doesn't seem quite right.

-jonathan

[Herron]

Jonathan~

Thanks. I will do as you recommend. We really don't feel it is fuel related but certainly checking this will confirm or elliminate it as the cause.

The engine does not act as if starved or flooded for fuel. And when stopping it show signs of stress as if a load was placed on her almost as if to seize. She'll start right up each time but will run for shorter and shorter periods of time unless she recovers for about 2-3 minutes. Any other thoughts?

Thanks!

~James

[David Masury]

I can tell you from experience that it more than likely is one of two things... first, even new condensors can be bad... replace it and your problem should go away. The second thing to look at replacing is the ignition switch.. it carries current and the contacts wear out or corrode.

I recommend using blue streak ignition parts rather than delco... a bit more expensive.. but good quality. Any good auto place can cross check the numbers for you.

On an antique tractor site that I frequent, since I own one, those are the two most common problems for the symptom you describe.

Best of luck,

David

[Herron]

Thanks David~

We're beginning to believe the problem is much more complex than the condenser and/or switch. The latest theory is that it is a bearing and/or bearing that when they begin to get hot close an oil port and thus starving the motor for oil and causing a seize activity. What do you think?

Thanks for your thoughts!

~James

[baileyem]

opinion

If you have a condition that is causing oil starvation and subsequent seizure enough to stall the engine you will not be able to start the engine again without considerable difficulty. Seizing is not a temporary problem!!! You will have to keep looking for the real problem.

Mike

[Herron]

Thanks Mike~

That was my feeling exactly.

However, consider this. If a main bearing and or bearings were slipping out of place and as the engine began to heat up, had covered the small oil port (small hole) then the engine would be starved for oil, heat and begin to quit and or seize. As the engine has time to cool following the event, it could allow this process to begin all over.

I've checked this theory with at mechanic at Journeys End Marina in Rockland Maine who concurs it is possible. I'm up for anything as I really am not looking forward to pulling the engine again. Any other thoughts?

Best wishes
~James

[Almer]

James,

I would still be inclined to think the issue is fuel related. Your theory of oil starvation and seizing has a few holes; primarily with the amount of time it takes for the engine to recover (“1-2 minutes to "kind of" recover”) in that amount of time the engine temp would most likely still be increasing; and it is certain that it would not allow for any cooling and contraction of parts to clear passages etc.
Have you checked the fuel system from end to end including the tank vent and fuel line condition (a soft hose can collapse under suction)?

Almer

[Herron]

Hello Almer~

Thanks for your contribution. Here's what I have checked regarding fuel. The tank was clean and free of debry before I added fuel after reinstalling the engine. The fuel screen (was removed after the problem began) even though it was clear. A fuel filter was added when we re-installed the engine. The carb and bowl was cleaned. I have not checked the float again because the engine will respond sharply and rev up even as it is beginning to quit. What do you recommend I check?

~James

[baileyem]

start-stop problem

I agree that the problem is in the fuel system. Take the carb off, clean it thouroughly and check the float level. If that doesnt do it you may have an air leak in the fuel system.

Mike

[Almer]

James,

The fact that the engine will respond to the throttle as it is dying does seem to point to an issue other then fuel; but I cannot believe that it is actually seizing up; you have stated that it can be restarted after a few minutes but can it be turned over immediately after quitting?

Fuel line checks would include checking for loose connections and clamps, fuel filter condition and installation (a backwards fuel filter can do some weird things), correct hose diameter and condition and a clear fuel tank vent (my system also has an electrically operated anti-siphon valve that I check).

Have you been able to run it long enough to get up to normal operating temp? How is the water flow?

I like your quote from the mechanic in Rockland; a good wrench will always admit that almost anything is possible!

Almer

[Herron]

Hi Almer~

Thanks again for your thoughts.

Couple thoughts. The engine starts immediatly after quiting, howver each time this is done she runs for a shorter and short time. If you wait about 1-2 minutes she will repeat the above process.

Water flow. Seems excellent. Temp is normal while running again and again, but of course we're not talking about any sustained length of more than about 2 minutes.

Yes. I imagine the Journey's End mechanic would welcome the work, yet in this case he was simply offering an opinion as a well respected boat engine man.

Can you better describe fuel filter incorrectly connected and also hose issues?

Thanks
~James

[Almer]

James,

No slight intended, a good mechanic needs to keep all options open and not fixate on just one area especially when you have done the amount of repairs you have.

Normally a fuel filter will have an arrow that indicates the direction of the fuel flow towards the carburetor.

Fuel hoses must be of the proper type and size for the engine to function correctly Don can advise on this.

Almer