Random tapping

[chrisoelder]

Hey everyone!

I was motor sailing for about 20 miles and I realized that I could hear a tapping coming from my engine compartment. I also noticed my oil pressure was down about 20-30%. After we finished our sail my oil was at a solid level, and when I started the engine the tapping still continued. Seems to be coming from the right hand side. Anyone have any thoughts?

Here is a video
https://drive.google.com/open?id=1HN...9zcJ25KgVDImTc

[capnward]

Sure sounds like a valve. It's in the right place, too. Are you using MMO in the gas and/or oil? If not, try adding it to both. I believe it prevents sticky valves. I always have used it in gas and oil, and have never had to open the valve cover in 20 years. If oil level is unchanged, maybe oil pressure decreased as engine and oil got warmer. Others will be along with more knowledge. This might be a good time to check your compression.

[roadnsky]

When was the last time you did a valve adjustment?

[chrisoelder]

Thank you for the replies!

@capnward I did and an oil and fuel filter separator change about 20 engine hours ago (April19) When I did that I added MMO to my oil and fuel. I’m going to add a bit more to my fuel and oil to see if that helps resolve it. Good idea! Fingers crossed it will be that simple haha.

@roadnsky I’m not sure the last time that was done. I bought her in April 2018 and the previous owner said they got a “complete tune up”. I don’t really believe them because shortly after purchasing I found the engine was over heating after 30 mins above idle due to a blocked L. So it’s anyone’s guess the last time it was done. I had a feeling it was a tapping valve. Is doing a valve adjustment a heavy labor project? The forum you linked makes me think it is haha.

Sorry for my lack of proper terminology


UPDATE: Added a bit of MMO to my oil and the recommended amount in my fuel with 5 gallons. I ran the engine for 15 mins, she started up on the 2nd try ran well but still ticked. I let her sit for 15 min and put a small splash of MMO in the oil. After the wait I ran her for another 15 mins. Good start up but still clicked.

2 questions:
1. Should I run the engine longer to get the oil through the engine?

2. Also is what I’m hearing a metal pin hitting a jammed or broken spring?

[capnward]

Apparently it wasn't as simple as adding MMO. The MMO may prevent carbon buildup on the valves, but won't break it down easily. That is a substantial tapping noise which indicates to me the need for a valve adjustment. I have never done one, but someday I will. I will probably need to remove the engine to get access to the valves. But if I do that I will likely replace the short block. Doing a valve adjustment won't necessarily solve the tapping issue. It might be in the mechanical fuel pump, if you have one.
I think you have run the engine long enough for the MMO to take whatever effect it will in the short run. The noise is, I'm guessing, the tappet hitting the end of the valve shaft harder than it would with a smaller gap between them, and carbon buildup on the seat of the valve elevated it a bit. I doubt the valve spring is broken or jammed. You may be able to run for years this way, but many others on this forum will have more experience than me with valves.

[ndutton]

Sounds more like an exhaust leak to me. Try pulling one plug wire at a time and see if the sound changes or goes away.