8.1 Slight Tick Noise

BleednBlue

Member
Jul 22, 2015
163
Lake Of The Ozarks
Boat Info
270 SLX
Engines
Merc. 496 MAG Bravo III
In the video below it does sound like a tick. In person, it sounds more like a quick hiss. I search this forum and the interwebs, it seems like it could be either an exhaust flapper or an exhaust leak from the manifold. You may need to turn up the volume to hear the tick noise. The first one happens right before the 1 second mark on the video. There seems to be no pattern while the boat is in idle. Once in gear the tick noise does increase with RPM. Lastly, it seems to go away after the engine gets to about 160 degrees.

Anyway, wanted to get your opinions. Thanks for your time.

[URL=http://youtu.be/KN0uQV1-Jsc] [/URL]
 
Last edited:
I have 8.1's and when cold, mine have a slight hiss noise until they warm up. Mechanic said that its normal - gave the name of the valve that is opened when cold.
 
tough to tell from the video, but could it be more of a very quick squeak? From the belt at a certain spot slipping ever so slightly, or a spot of friction on one of the pulleys?
 
tough to tell from the video, but could it be more of a very quick squeak? From the belt at a certain spot slipping ever so slightly, or a spot of friction on one of the pulleys?

Agree +1
 
Sounds like it's intermittent. Is it a constant, same time tick? Almost like a spark plug wire grounding. When' its dark check all around and see if you see something.
 
Spray the belt with water and see if it quiets down for a few seconds. If it does it's the belt.
 
Thanks all for your responses.

tough to tell from the video, but could it be more of a very quick squeak? From the belt at a certain spot slipping ever so slightly, or a spot of friction on one of the pulleys?

I guess it could be a quick squeak. When I first heard the noise my initial thought was belt. After searching the internet my mind got stuck on exhaust. I will check the belt and pulleys this weekend.


Sounds like it's intermittent. Is it a constant, same time tick? Almost like a spark plug wire grounding. When' its dark check all around and see if you see something.

In neutral, yes it is intermittent. Once in gear becomes constant and noise frequency increases with RPM. I will do the dark test this weekend.


Spray the belt with water and see if it quiets down for a few seconds. If it does it's the belt.

I will do the spray test. Probably as stupid question, but how much water should be sprayed on the belt? Certainly do not want to use a hose right?
 
Use a spray bottle - like a re-purposed Windex bottle (don't use windex!)
 
Sounds like an exhaust flapper gone bad. If so, don't slow down fast! Until repaired. Engines don't like hydro-locking.
 
You guys are good. Water spray test on belt stopped the noise for about 3 seconds. So what is next? Replace the belt? How soon should this be done?
Many thanks!
Rich
 
You guys are good. Water spray test on belt stopped the noise for about 3 seconds. So what is next? Replace the belt? How soon should this be done?
Many thanks!
Rich

Good deal. Belt replacement is fairly easy assuming access and the proper tools. Make sure you tension it correctly and you should be good to go. Also, take a picture so you know how the belt is installed, unless you've got the diagram handy. Also, as an FYI, I'd get a spare belt when you buy the replacement always good to have one on board in case of failure cheap insurance if your 30 miles out and one shreds up on 'ya.
 
My 8.1 has a diagram of how the belt is "strung" right on the motor.
 

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