Random tapping
 

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

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.

When was the last time you did a valve adjustment?

MMO and valve adjustment
 

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?

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.

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.

You know what?
I went back and listened and I think Neil is right.

By golly, now that you mention it, I can hear it too. Good ear, Neil.

Wow! I can’t believe it. When I remove the plug for the 4th spark plug back (the last spark plug) the ticking stops. I’m assuming that is my issue right there. I’m going to get a replacement.

Is there anything else I should do? Also does anyone know the toque wrench setting for this head?

First time doing this on my A4. Thanks!

What exactly are you replacing?

@ndunton I was going to replace the spark plug and the plug cable for it. Sorry for the confusion

If the plug and wire replacement results in no change we will discuss things further. Do you have a compression tester? I'd like to know about #4.

Sounds good to me. I dont have one but will look into it. Ordering the parts now and will have some info in the next week.

Thanks for the help everyone!

Hey everyone!

Alright so i replaced the spark plug wires and the plugs. Sadly, the tapping is still happening.

When i remove the plug wires one by one, while running, the tapping stops when i remove the 4th spark plug wire (last one, closest to the oil). My compression tester should be in tomorrow so i can test compression.

I have done a bit of research and i have found that people will pour/spray MMO and Sea Foam right into where the spark plug is, do you think i should try this to help resolve the issue?

Could the issue stopping after removing the 4th spark plug wire mean that the 4th spark plug provides power to the back valves that are causing a tap?


Thanks for the help and sorry for my ignorance!

I'm thinking it might be time to do a Valve Adjustment.

Does anyone else concur or have a better thought?

@ Chris - If we go to adjusting valves, I'll link you to a couple of really good instructional threads about this procedure.

There is no downside to a valve adjustment and he'll be able to visually check their motion and spring condition.

Valve Adjustment
 

@roadnsky

Send it over please! Would be good to know either way. Do i need a lot of room to accomplish this?


Before i dive in, do you think pouring MMO or Sea Foam into the head would help at all?


Thanks All!

In your original post you mentioned oil pressure dropping ~30% when the tapping started, right? When you depower #4 the tapping stops. I'm not seeing how these are related to valve adjustment. I hate to tell you this, but these symptoms DO point to connecting rod knock. Something may be going on with that #4 rod bearing.

But ... by all means rule out the easy stuff first; Valve sticking/adjustment, exhaust manifold leak.

@wristwister

That is very possible. Here is the situation:

I had been under power for a total of 7.25 hours heading to Catalina Island. We were healing over for the last 2.5 hours, I noticed my oil pressure around 25-30. There were some big rolling swells and wind gusts. Very confused seas for that 2.5 hours. I heard the small tapping sound and brought down the throttle completely. Investigated and determined it wasn't major. Checked the oil and the level was just about full (i did an oil change a couple months ago). Got safely into Catalina and started poking around.

After a couple days of being at the island and diagnosing I thought it was a valve tap. I poured some MMO into my oil and fuel. I power sailed on the way back for about 7.5 hours with very little issue. The tapping was still happening but the oil pressure looked good and the engine didnt have a problem running on low RPM.

Since the sound was coming from the right side i thought it was a valve tap. (I have a video of it in the first section linked) I also checked my spark plugs to make sure they were solid. While running the engine when i remove the spark plug wire from the 4th plug the tapping stopped. There was no change when testing the others.

I am not much of an engine person but am trying to learn. Hence why i bought a boat with an Atomic. Any and all help is greatly appreciated! I have a compression test arriving today or tomorrow, im not sure if it will help.

Thanks all!

I am sure Neil is right.

See attached screen shot. There is black soot coming out from a bad exhaust gasket n on number 4 ex port.

Put in a new exhaust gasket.

Also, understand you now have a carbon monoxide leak in your boat! Get it fixed ASAP. Don't die.

Russ

Has the possibility of an exhaust leak been eliminated?

Peter

Not in my view. the noise is more like "piss piss piss" than clacking.

@lat 64

Thank you! That does make sense. It isnt a very loud sound, its very subtle. Would preforming a compression test confirm the exhaust leak issue?

Also would disconnecting the spark plug wire stop the sound?

Past history: When i first got the boat/engine (Apr 2018) i had an overheating issue. Found out that it was the stern facing L was clogged with gunk. Cleaned it and the overheating issue when away. Correct my assumption but is it possibly that the pressure build up caused by the blocked L (water and exhaust) put pressure on the exhaust manifold and the gasket causing this issue to eventually happen?

I took a few more screen shots of my exhaust manifold. To show the soot towards the back

https://drive.google.com/open?id=1nA...DOEpLSBq0zmsvZ
https://drive.google.com/open?id=1V2...SDilj7-ZYQ8wNo
https://drive.google.com/open?id=1Uh...Wq2Yvk11dqyFwp

Thanks all!
Chris

Your screen shots show rust where the paint burned off the nuts. I think.

The exhaust gasket is on the other side of the manifold, between it and the block.

Neil had you disconnect the plug so the #4 cylinder would not fire. If there is no fire, It will not burn the fuel/air mixture and there will be no combustion sound—no pop or the "Pisst" that we hear. The "Pisst" is the hot exhaust gas leaking out the failed gasket.
So the noise is gone in that test.

A compression test will not be useful testing for a gasket leak at this spot. A compression test measures only the pressure inside the combustion chamber when both valves are closed. The gasket in question is outside of that; downstream of the ex valve.

Great video, by the way.

Cheers,

Russ

@lat 64

Its all making sense, learning a lot! Thanks again for the explanation.

Alright so what i need to do is order a new gasket and replace it.

Does anyone have any tips or tricks to removing an old gasket and installing a new one? Anything i should know?


To confirm: this is what i am replacing.
https://drive.google.com/open?id=1Sn...UuYd6-eZefk-wy