Technical Anomaly
Over the years I have been grateful for the great deal of wisdom shared on this site. Now, I write my first post with my first Atomic 4 challenge that I am unable to solve. I have a 1981 Catalina 30 for 23 years. I took Don’s course and rebuilt my late model engine in 1994. I have had flawless performance until the summer of 2009. I stayed in the water for my winter lay up. During the winter my marina conducted an extensive dock and piling replacement.
Upon spring commissioning start-up, the engine immediately started up and after 2 minutes began rumbling and vibrating severely. Fearing that I ingested some lingering construction debris in the intake, I immediately shut the motor off to check the intake, plugs and wires but all was clear and the problem never went away. Cylinders 3 & 4 quit firing.
Currently, I am still firing on only 2 of the 4 cylinders. Cylinders 1 & 2 are fine with 3 & 4 not firing at all. I have better than 100 psi in each cylinder. I have completed the following component replacements.
Ignition: I have replaced the spark plugs, plug wires, points, condenser, ignition coil, distributor cap and button.
Fuel: I replaced the fuel, fuel pump, and re-built the carburetor.
Exhaust: Fearing back pressure, I replaced the hot section of the exhaust, aqua-lift muffler, 3 feet of exhaust hose immediately after the aqua-lift muffler, removed the anti-back flow butterfly valve in between the muffler and the transom and manually bored out the exhaust hose to verify no blockages.
Mechanical: I removed the manifold to adjust the valves and validate the integrity of the valve springs and operation. Nothing is sticking and all valves and timing are exactly adjusted. I have a 2 year old Moyer Marine manifold in perfect condition.
My dear wife is convinced I am obsessed and fearing for my sanity agreed with Don’s suggestion to take a step back and get a second opinion. I asked Dr. Will Sibley of Sibley Marine to examine and comment on this situation. The engine started immediately and Will observed excellent spark at 3 & 4 both direct and indirect with added resistance to the plug. We disconnected the exhaust flange and ran the motor with no exhaust at all. Thankfully, he confirmed all that I state above with 3 & 4 still not firing. Don reminded me that we are still smarter than the engines. I am anxious and grateful for any suggestions you may have.
Over the years I have been grateful for the great deal of wisdom shared on this site. Now, I write my first post with my first Atomic 4 challenge that I am unable to solve. I have a 1981 Catalina 30 for 23 years. I took Don’s course and rebuilt my late model engine in 1994. I have had flawless performance until the summer of 2009. I stayed in the water for my winter lay up. During the winter my marina conducted an extensive dock and piling replacement.
Upon spring commissioning start-up, the engine immediately started up and after 2 minutes began rumbling and vibrating severely. Fearing that I ingested some lingering construction debris in the intake, I immediately shut the motor off to check the intake, plugs and wires but all was clear and the problem never went away. Cylinders 3 & 4 quit firing.
Currently, I am still firing on only 2 of the 4 cylinders. Cylinders 1 & 2 are fine with 3 & 4 not firing at all. I have better than 100 psi in each cylinder. I have completed the following component replacements.
Ignition: I have replaced the spark plugs, plug wires, points, condenser, ignition coil, distributor cap and button.
Fuel: I replaced the fuel, fuel pump, and re-built the carburetor.
Exhaust: Fearing back pressure, I replaced the hot section of the exhaust, aqua-lift muffler, 3 feet of exhaust hose immediately after the aqua-lift muffler, removed the anti-back flow butterfly valve in between the muffler and the transom and manually bored out the exhaust hose to verify no blockages.
Mechanical: I removed the manifold to adjust the valves and validate the integrity of the valve springs and operation. Nothing is sticking and all valves and timing are exactly adjusted. I have a 2 year old Moyer Marine manifold in perfect condition.
My dear wife is convinced I am obsessed and fearing for my sanity agreed with Don’s suggestion to take a step back and get a second opinion. I asked Dr. Will Sibley of Sibley Marine to examine and comment on this situation. The engine started immediately and Will observed excellent spark at 3 & 4 both direct and indirect with added resistance to the plug. We disconnected the exhaust flange and ran the motor with no exhaust at all. Thankfully, he confirmed all that I state above with 3 & 4 still not firing. Don reminded me that we are still smarter than the engines. I am anxious and grateful for any suggestions you may have.
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