Quiet ticking noise

[ranger481vs]

I’m hearing a slight ticking noise in my engine. It’s fairly quiet. Seems like there are a lot of possibilities for what could be causing it, so I’m not sure where to start investigating. NOTE: In researching ticking Mercruiser, someone had a similar noise, and it was said it was the electric injectors and was normal sound.

Anyhow, some background: Boat was winterized with all water completely drained and block left empty. oil/filter was changed and level is good, no alarms, oil pressure good, as well.

In the video below, you can see me putting the stethoscope underneath plastic cover on the left side. That’s where the sound was most prevalent, but didn’t listen anywhere else

I also listened to the y pipe and heard a subtle chatter from the flappers, but it sounded different and quieter.

Anyhow, could use some guidance on what to start checking first. Thank you!

 

[Stinnett21]

Water shutter possibly. Remove starboard exhaust bellows (if that's where it's the loudest) and see what you have. Once the rubber wears off of them nothing is left but the metal and the metal is hitting the side of the exhaust down elbow.

 

[ranger481vs]

Water shutter possibly. Remove starboard exhaust bellows (if that's where it's the loudest) and see what you have. Once the rubber wears off of them nothing is left but the metal and the metal is hitting the side of the exhaust down elbow.

I did put the stethoscope on the pipe where the flappers are, but it sounded different there and quieter than when I was listening underneath the engine cover area in the video.

Regardless, I do need to check the flappers anyhow, so we’ll see.

 

[ranger481vs]

Is definitely not the flappers. I opened the exhaust tubes, one set of flappers was nice and quiet, and the other was completely missing. So, I'll be hunting for that set of flappers this weekend and replacing both.

Anyhow, the noise is heard when I put the stethoscope on top of the block near the back. Wondering if this is just the fuel injectors, since it relatively quiet.

I'm coming from an outboard world, so I'm learning a lot about sterndrives these days, thanks to boats.

 

[H20Rat]

First thing to do is take the belt(s) off and see if the noise is still there. You would be surprised at the number of times a failing idler or even a bad belt makes that exact noise.

 

[ranger481vs]

First thing to do is take the belt(s) off and see if the noise is still there. You would be surprised at the number of times a failing idler or even a bad belt makes that exact noise.

I could do that, but I pinpointed the noise near the back of the block with my stethoscope. Not sure how to run engine with no belt, since my water pump is part of that.

So, a few guys on a Mercruiser FB forum said this noise was normal injector noise, but I’m not sure if that’s correct

 

[tpenfield]

Not much of a noise, but . . . my guesses are

Valve lash/adjustment
Belt
Exhaust reverberation/shutters
Domestic terrorism

 

[ranger481vs]

I will work on doing a compression test because I have not done one with this engine yet, or any engine for that matter.

 

[Lou C]

If you don’t have a mechanics stethoscope I’d get one and try putting the probe on various areas and see where it’s loudest. Try it on the valve covers (valve train) and on the exhaust manifolds (exhaust leak)....

 

[ranger481vs]

If you don’t have a mechanics stethoscope I’d get one and try putting the probe on various areas and see where it’s loudest. Try it on the valve covers (valve train) and on the exhaust manifolds (exhaust leak

 

[ranger481vs]

Yes have one and mentioned it the 1st post. Hearing the noise on the valve cover, so probably a valve issue. Will be doing a compression test next

 

[Lou C]

Ok yes read your first post too fast lol. You might then wind up having to re-adjust the travel on the hydraulic valve lifters. Its a little confusing at first but not hard if you take your time. The exhaust will have to come off to get clearance to remove the valve covers. I did mine when I did a top end overhaul on my 4.3 V6 4 years ago. Its basically a matter of getting the crankshaft in the right position (compression stroke of #1 cyl) then you adjust certain intake and exhaust valves, then you turn the engine till its at the compression stroke of #6 cyl and finish up with the rest intake and exhaust valves. You loosen the lock nut adjustment till you can just move the pushrod up and down, then tighten it till you can't...and go one more full turn (according to GM manuals I have seen, but some people use 3/4 turn some use 1/2 turn). Best to get a Merc or GM manual and follow it if you do this job. This is known as the 2 step method but there are others as well.