Clicking, Shaking, Power Loss at higher RPM under load

[s_czechowski]

[FONT=verdana, geneva]I'm looking for help/ideas on my 1978 Sea Ray 260 (Chevy 350). The boat was running great but suddenly lost power. When in neutral everything sounds normal and I can get above 5000rpm with no issues. However, under load, I hear a clicking noise that gets worse as speed increases, I can't get past 3000rpm, the engine is shaking by the carb (see video).

Personally, I think the idle sounds rougher than normal, and the exhaust sounds like it's spitting too. These could be normal though and maybe I'm overthinking symptoms.[/FONT]

[FONT=verdana, geneva]Anyway, I checked the distributor cap and there was no cracks or moisture, so I cleaned up the corroded inside terminals. I checked the prop and outdrive for any obstructions and didn't see anything besides some minimal seaweed. The fuel pump indicator didn't have any fuel in it so I'm assuming it's good. I pulled the water-fuel separator and it was full of what I thought was mostly water. I didn't look for separation, but it didn't smell that strongly of gas. I changed the separator, added SeaFoam and gave it another run, but nothing changed. One guy suggested that I probably have water in my gas. Before draining the entire tank, I emptied the new separator, into a clear container and let it settle. There was about 5% water at the bottom.[/FONT]

Anybody got any ideas? They WILL be greatly appreciated.

Also, if anyone thinks I should drain the tank and give it a go with fresh gas, does anybody have any good tricks on this? I figure I got about 30 gallons of gas in there.

 

[Bondo]

[FONT=verdana, geneva]However, under load, I hear a clicking noise that gets worse as speed increases, I can't get past 3000rpm, the engine is shaking[/FONT]

Ayuh,..... Welcome Aboard,..... That clickin' noise is yer motor consumin' itself from detonation, caused by a lean condition,....
The noise is bits, 'n pieces of the spark plugs, valves, 'n pistons flyin' off,...

Ya better do a compression test to see how bad ya burnt it up,....

Water don't burn like gasoline, hence the lean condition induced detonation,....

Ya don't have to drain the whole tank, just the water, which is on the bottom of the tank,....
Ya just gotta get the water out, 'n keep it out,...
The fresh gasoline above it is still good gas, if it's Fresh,....
If it's Old gas, pump it all, 'n trash it,...

 

[alldodge]

I emptied the new separator, into a clear container and let it settle. There was about 5% water at the bottom.

If the gas is old and E10, you need to drain it. If its new and somehow just got the water in there, then may get away with draining just the water

 

[s_czechowski]

Bondo and AllDodge thank you both! I will drain the tank and start fresh with some new gas. Hopefully there isn't much damage.

 

[s_czechowski]

One more question, if there's water in the gas, which we are pretty sure is the case, wouldn't that cause issues with the engine starting and running in neutral?

 

[Scott Danforth]

One more question, if there's water in the gas, which we are pretty sure is the case, wouldn't that cause issues with the engine starting and running in neutral?

NO.

your motor will run and start and run till the pistons fly apart on a mixture of 60% gas and 40% water simply because the amount of fuel needed for the load is miniscule. running in neutral to 5000 RPM can even be done with 4 of the plug wires disconnected. that test does nothing but potentially over-rev your motor

running under load, you need pure fuel going to your motor

 

[harleyman1975]

I would also drain the fuel out of the carb's float bowl's. Looks like a holley in the pic. Try just removing the lower screws and loosening to uppers and giving bowl a little tap.

 

[s_czechowski]

No Title

Ok, I drained the gas. I looked at every gallon that I pumped out and saw almost no water. However, I still have yet to start her up on fresh, ethanol free gas.
In the meantime, I took harleyman1975's suggestion and loosened the lower screws on the carb bowl to allow it to drain. I chose the side that seemed to have blackish oil like dirtiness around it. The fluid drained seeminging clear, then dark. I have a sample and it for sure looks like there was water in there, but why is the gas so dark? What else could be wrong or did I mess up and drain the wrong thing.

 

[achris]

Wow, I listened to the video. That sounds like an exhaust valve. Do a compression test. Bet you'll find one cylinder at 0....

Chris......

 

[s_czechowski]

No Title

Anyone ever have a stuck exhaust flapper? If its obstructing half of my exhaust could it cause the clicking and power loss? I think this is what I'm looking at, now I just have to get the SOB out. I read about a guy who had a similar issue and he did a ton before he figured this out. When I poked at this with a coat hanger it feels like strong but flexible rubber. It will somewhat "flap" open when i pull on it but it's either really stuck or secured. These are supposed to be higher up in the exhaust system, right?

 

[achris]

Anyone ever have a stuck exhaust flapper? If its obstructing half of my exhaust could it cause the clicking and power loss? I think this is what I'm looking at, now I just have to get the SOB out. I read about a guy who had a similar issue and he did a ton before he figured this out. When I poked at this with a coat hanger it feels like strong but flexible rubber. It will somewhat "flap" open when i pull on it but it's either really stuck or secured. These are supposed to be higher up in the exhaust system, right?

Right. And you need to get it out. If you don't it will eventual;ly wear a hole in the exhaust pipe and then let water (LOTS of water) into the boat.