I have a 2004 sea ray Sundance...

[Chief70]

I have a 2004 sea ray Sundance 380 with 8.1 Horizon Mercruisers. The engine on the port side has a ticking/ knocking sound only when transmission is engaged. And only when motor is cold. As soon as engine gets warm the tick/ knock stops. Any ideas on what that is?

[KevinC]

The 8.1s are known for eating spark plugs - I would start there. They can even cause a sound in the transmission that is like rattling marbles when there is a slight miss - all while the engine appears to be running smooth.

[Chief70]

I had planned on changing plugs before I splash in the spring. Thanks

[GottaCruise]

I had the same exact problem. My mechanic said it was the engine and it probably needed the fuel injectors cleaned. Seemed strange to me as it was only making noise when in gear, forward or reverse. Turns out the mechanic was correct. Replaced fuel filters, and spark plugs and cleaned the injectors. They were in bad shape. Port side was running on 4 cylinders and starboard was running on 6. Now she runs like a champ!

[Len1]

I too had the same problem on a 2007 36 sedan bridge with the 8.1s. Transmissions are the ZF63A. Starboard transmission sounded like it was full of marbles when in gear at idle speed. Turns out these transmissions are famous for transmitting sound from other parts of the engine, i.e. crankshaft play, etc. My problem was a bad injector. Replaced the injector. Engine ran great and it eliminated the knocking sound from the transmission.