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Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Gas > Atomic 4
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Old 06-24-2007
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Engine woes...please help!

I have an A-4 and have had recurring problems with the engine from the start. I lost it going from King Harbor to Del Ray two years ago. That was a bad head gasket. Symptoms were: loss of power, then dead. Re-start, loss of power and dead...finally, no re-start.

Shipped the boat to Portland, and did the following: Re-built carb, new head gasket, new plugs, points and condenser, cap and rotor, new coil and distributor, new fuel lines and filter. Ran ok, but not great, so new carb, new fuel pump, new fuel/water separating filter, new plugs. Ran pretty good.

Then, took the boat to Astoria and lost the engine on the trip down the Columbia. Symptoms were loss of RPM, dead. Restart, loss of RPM and dead...finally dead.

Then, took the head off, machined it, new gaskets again, changed thermostat and housing, as the old one was stuck open. New RACOR fuel/water separating filter, New plugs again, and new plug wires, as No. 1 wire broke at the bend at the plug. Ran great, so sea trialed for two hours and thought we finally got it fixed.

Saturday, set out for trip to Seattle, and the same sypmtoms occurred again after only 1/2 hour on the water. Aborted and limped back to the berth. In trouble shooting since then, have loosened the packing nut so it drips fairly freely as it was a little too tight. New fuel pick up tube and fittings. New line from the tank to the filter...it was the only one I hadn't changed previously. Checked points gap and found it too tight, so loosened up to the .020 spec. Found that the condenser wire had been abraded by the rotor, so fixed that with RTV silicone and pushed the wire out of harms way. Tightened all the fuel line fittings and checked the internal fuel pump filter just to make sure no pinhole or gaps for air to enter.

The symptoms are that it runs great with no load. I can get all the RPM I want up to 4500...as far as I wanted to take it. I then put it under load, forward OR reverse and can only get 1200 to 1500. It ran at 2,000 to 2,500 just fine last week before I did the other stuff yesterday in troubleshooting and repairs. Then, took the carb out last night to check for anything that might be in the carb and it was OK...

After serious consideration and several hours of troubleshooting, it appears there may be a constriction of the prop shaft, as in a bearing that is siezing maybe? Anyway, it is a thought. If anyone has an idea of how this goes together, whether there is a bearing or a bushing and if it can be taken apart without hauling the hull, I would appreciate the knowledgebase....thanks again for anyone's help

Thinking my next step is exorcism...any ideas, no matter how silly sounding, will be gratefully accepted.

C-30 TRBS #1269
SV Solus Deus

"Every time I go sailing I learn something new or I remember something I forgot" Usually with the highest order of embarrassment.
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Old 06-24-2007
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Disconnect the shaft from the trans. You should be able to turn the prop shaft by hand. If it requires a pipe wrench to move with much force, then you have a shaft problem. If it turns freely by hand, then it's an engine problem. Lack of power under load is usually a fuel problem. These guys work with nothing but A-4's, maybe they can help also. Google-ing Atomic Four Marine Engines, brings up a wealth of info as well.
Moyer Marine Atomic 4 Engine Rebuilding and Parts
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