Opinion on Engine Noise

[lawndoctor]

Any opinions on what the clacking sound is? (Link to video with sound below.)

The engine runs perfectly, no performance issues. The sound is at idle, not at high speed. It does not change whether the engine is in gear or not. My mechanic says the sound is normal, but it was not there last season, so I'm having trouble believing it is normal. I'm hoping it is just the exhaust shutters.

I realize using a video for this is not ideal, but any thoughts would be much appreciated.

https://www.youtube.com/watch?feature=youtu.be&v=0V6SU1Xljok&app=desktop

 

[joeyleggz]

Not trying to scare you or anything but I believe I had a very similar sound at the beginning of my season was told it was just transmission as I have an inboard nothing critical waited till the end of the season to do a compression test and found two bad cylinders put fresh plugs in take for one more ride wound up with a spun bearing now I need to replace the motor sometimes engines make a similar sound when you're down a cylinder or two really not that hard to do a compression test I would jump on that first thing to see what's really going on


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[BillK2632]

I would start with the exhaust shutters, should be easy to pull the hoses off and check. Does the sound go away or change frequency at higher RPM?

 

[lawndoctor]

Thanks guys. The sound goes away above idle. The engine runs like a top (4400 rpm and 43 mph at WOT, as always) which I think (and hope) militates against one or more cylinders not firing properly for whatever reason. I'm thinking of changing out the shutters to see if that does the trick. It would be a relatively easy and inexpensive first (and hopefully only) step.

 

[JimG]

Another thing that comes to mind is a cracked harmonic balancer... had that happen to a 7.4L and it sounded like a valve tap.

 

[CliffA]

if you are talking about the slight whining noise I would suggest you get a mechanic's stethoscope and listen to the bearings on all the pulleys on front of the engine.....if they sound quiet move the stethoscope around the engine to see if you can pinpoint where the whine is coming from....you can get a stethoscope at just about all auto parts stores or Harbor Freight for just a few $$.....

same procedure for locating a tapping or knocking noise....

other than that I really did not hear much of anything I would be overly concerned about....

cliff

 

[Sprint7TW]

if you are talking about the slight whining noise I would suggest you get a mechanic's stethoscope and listen to the bearings on all the pulleys on front of the engine.....if they sound quiet move the stethoscope around the engine to see if you can pinpoint where the whine is coming from....you can get a stethoscope at just about all auto parts stores or Harbor Freight for just a few $$.....

same procedure for locating a tapping or knocking noise....

other than that I really did not hear much of anything I would be overly concerned about....

cliff

A wooden yardstick or a piece of heater hose will do the same thing for you. Hold the yardstick to your ear and any unusal sounds will be amplified. just move the yardstick around until you hear it if it is external noise.
Hard to tell if it is a rod or main bearing unless you can get it on the pan when it is running.

 

[joeyleggz]

Thanks guys. The sound goes away above idle. The engine runs like a top (4400 rpm and 43 mph at WOT, as always) which I think (and hope) militates against one or more cylinders not firing properly for whatever reason. I'm thinking of changing out the shutters to see if that does the trick. It would be a relatively easy and inexpensive first (and hopefully only) step.

Yeah my motor ran like a top too you be surprised how well they can hide being down a cylinder I ran to watch hill and back with absolutely no issues over 70 miles ,purred like a kitten other than that noise at idle compression test is easy to do and I will tell you exactly if there is an issue with the motor shouldn't take you more than a half hour or so


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[LG111]

The only thing I hear are the injectors clicking. Normal.

 

[Strecker25]

Talking about compression tests, I'd like to do mine this winter/spring. Can someone detail the steps on a TBI/FI engine? Do you just take one plug out at a time, thread in the tool and turn over a few times? I would think taking off the main lead to the distributor is enough so it won't start but any concern with the injectors dumping fuel in during the process?