Engine Tick or Knock?

First post. Novice mechanic and beginning to learn about nautiques. Hope to be a Nautique owner in the near future, so bare with me

My friend has a 1990 sport nautique, PCM 351 with 1250 hours. Just had the transmission replaced and first time on the water the boat developed a loud tick/knock at idle and while running. It can only be heard under load and while underway. The sound is more pronounced the longer the engine runs.

My first thought was a stuck lifter as the boat sat around for six months during repair.

I searched the forum and came up with an action plan:

A. Use screw driver and stethescope to pinpoint origin.

1. Change oil.
2. Try Rislone.
3. Check spark plugs/distributor cap - one at a time.
4. If noise doesn't improve move on to second phase.

I know it may be something else, just trying the low hanging fruit first. Let me know what you think.

Something else it could be is what plagued me for the past two years....bad exhaust gaskets! When they burn through the fiber that is stamped on the metal, it will make a popping sound, and lead you to believe it is something more serious. You may want to take off the exhuast manifold(s) and check them out. Yes, its a PIA, but, may be a lot easier and lower cost than taking the engine apart.

The solution: Percy's XX Carbon Gaskets made for such a situation, along with some high temp Copper gasket material to fill in any low spots on the head exhaust port where the exhaust gas may be burning through the gaskets.

Or: Pull the heads and have them, or the ehxaust manifolds, machined flat to eliminate low spots where the gas burns through. I opted for the solution above as I didn't want to pull the heads right now.

Let us know what you find the issue to be.   

Then take the belt off for a moment and see what happens.

lifter or rocker arm

Thanks for the response. We're keeping an eye on it. It's not my boat so it's tough to find the time to work on it. I have to lug my tools around with me.

Not sure what a damper plate is. Googled this:

http://www.alberg37.org/Project%20DB/SHEARWATER_DamperPlate-08/Transmission_Damper_Plate_Install.htm

and

http://skidimforum.com/ski-nautique-transmission_topic149.html


We changed the oil and only about 2 qts came out. After oil change the boat has been running better. Our hope is one of the lifters/valves dried up while it sat. Especially over the winter. Thanks for all the advice.

I enjoy learning about the older nautiques. Currently looking at an 89 2001 for myself. I like the smaller models. The 21' - 22' boats are a little big for my yard.