Strange Engine Noise
 

Hey guys,
Just started my boat today for the first time. Everything seems to be running fine but I'm getting a strange clicking sound from inside the engine compartment. It is not an enternal sound, as i used a mechanics stethascope and couldnt hear anything coming grom inside the engine itself. It seems to be coming from the very back around the drive shaft, and it sounds similar to a belt or something plastic hitting against something. I know this is very vague but any suggestions or thoughts would help.

exhaust flappers?

Dry U-joint or bearing?

I agree, sounds like flappers, you sure it wasnt there last year and maybe you didnt notice it?

You could try shooting a little grease in the u joint and gimbal as suggested above also, couldnt hurt

Coil grounding out...? Or plug wire..??? Electrical click...?

I fired up mine today for the first time after some work (water pumps, intakes, carbs) and 1 engine was making a ticking noise. I was instantly thinking horrible thoughts - pistons, push rods... I found that the timing guide plate had gotten pushed down and was hitting. Bent it up and back in business. I hope your noise is just as simple, but sounds like you isolated it to the azz end.

Internal exhaust flappers. Put your hand on the tail pipe/exhaust hose near the transom and you will feel it.

Thanks for all the input, what exactly are the exhuast flappers, is that what controls my captains choice exhaust? Is there a grease fitting for the u joint and gimbal? about 85% positive it wasnt there last year.

There are flappers/diverters for the capt choice and there are also flappers in the exhaust tips to prevent water intrusion.

I had an internal flapper come apart on a previous boat. Rattled like hell, but was an easy fix.

I'm assuming you're on the trailer and running on a hose? Are your drive(s) "binding"? Are they trimmed all the way up?

Try switching the exhaust and playing with the trim and see if it changes anything.

Exhaust flappers will make more noise on the hose than when the boat is in the water. There is much more water flow past them when the boat is in the water which quiets them some.

I am a little confused with the focus on the exhaust flaps.....?

I have the "noisey" internal flaps in my system and when I first got the boat I heard the noise and was not sure what it was until explained to me....the noise does NOT sound like a "clicking" as described above and I would think would definatly be heard through a stethascope as used above...??

A clicking noise could be an electrical current arching..??

Not sure what engine this is but I believe most Mercruiser units have the coil and other electrical components towards the rear of the motor where the noise was described coming from?

I am guessing a loose wire or plug boot....:coolcowboy:

First off, yes the boat was on the trailer with a hose attached to it, and when i think about it, this was the first time I really ran it a while out of the water with the hatch open.

engine is a 454 mag, and yes the distributor and coil is located in the back. The click didnt have any sort of consistancy to it, just random, and as i tried reving the engine I didnt notice the sound speeding up (although it was harder to hear with the motor revving). If the sound was from an arching, wouldn't it speed up with the engine revs? I also didnt put the stethascope against the exhaust. Plan on putting the boat in the water this sunday, so i will be testing all these theories.

Also, I actually put the trim all the way down, so it could have been with the drive, but again, the noise didnt speed up with the engine... Ill keep you guys posted on my findings!

My SeaRay with thru-drive exhaust (Bravo 3) has the same issue- a random clicking caused by the exhaust flappers in the down pipe. Its just a minor irritation at idle when the engine hatch is raised- any other time you cannot hear it.

Internal exhaust flapper noise is not consistent and is as you describe. Also, the angle of the boat when its on trailer is different than when its in the water and that can angle change can make them rattle more.