Can anyone tell me what this noise is

[cshep215]

Originally Posted by Cadence

Is the brass colored item next to the hose a valve that may be not seated and whistling?

I did check the brass fittings leading into the fuel pump, none of them seamed to be loose or vibrating.

Thanks for the suggestions

[Bill Seal]

It sounds like the noise the power steering pump on a car makes when the steering wheel is turned to full lock. If so, the valving on a hydraulic device like autopilot or trim tabs is probably messed up and the pump is over-pressurizing. Or maybe air in the hydraulic lines.
Just my WAG.

[Scubaseas]

Originally Posted by cshep215

I will be back to the boat next Saturday to Try each of your suggestions. During all of this I did start hearing the serpentine belt occasionally skip and squeal so that definitely needs to be replaced. I did notice just before I left, for what ever reason when I hit the trim tap buttons the pitch of the noise dropped in tone and when the buttons were released the pitch of the tone went back up. I have never noticed the trim tab controls drawing power from the engine before. It didn’t not cause any change in the engine RPMs nor seem like it was drawing power from the engine itself but it did make a significant change in the noise.

Thanks

Could easily be the trim tab motor running making the noise. If the switch or relay is broken in the "on" position it'll command the pump to run all the time. Take the fuse out to the trim tab pump and see if the noise stops. The trim tab pump is separate from the engine and not a factory option from what I can tell.

[inspectr]

Second the use of a stethoscope to localise a noise source
I used a 600mm length of hose and a small plastic funnel jammed in one end to synchronise twin SU carbys on my old 1962 MGA 1600 MK2 sports car - worked better than any other professional tool to get the sound of the air intakes exactly the same

[cshep215]

First off I want to thank everyone for their help locating the noise. The stethoscope really worked and located the noise. It appears the power steering pump is going out. Everyone’s suggestions made it easy to find.

However the great thing about boat ownership is once you remedy on problem another seems to pop up. Exhaust smoke is billowing out of the starboard side of the lower unit cowling. Any suggestions of what maybe causing this?

[Cheechako]

I hear a high pitched whine, but I dont hear a buzz. If you mean the whine it sounds a bit like V belt noise. Some pulleys will do that. Could be alternator noise too. Try spraying the V belt with something and see if it stops.
V belt noise would makes sense when you say it changes with rpm also.

Or: Is your trim tab reservoir low on atf? or is yours electrical?

Whoops, Now I see you found it!

[Scubaseas]

Originally Posted by cshep215

... Exhaust smoke is billowing out of the starboard side of the lower unit cowling. Any suggestions of what maybe causing this?...

Not enough raw water maybe? Usually if you have restricted raw water flow it will burns through the exhaust hose eventually. Check how much raw water flow you have. Possible clogged mixing elbow or heat exchanger. Or bad impeller or clogged inlet or strainer. Might be normal but for lack of cooling water.

What does the smoke smell like if at all? And does the smoke go away at any time?

[Boatyarddog]

Originally Posted by cshep215

First off I want to thank everyone for their help locating the noise. The stethoscope really worked and located the noise. It appears the power steering pump is going out. Everyone’s suggestions made it easy to find.

However the great thing about boat ownership is once you remedy on problem another seems to pop up. Exhaust smoke is billowing out of the starboard side of the lower unit cowling. Any suggestions of what maybe causing this?

I have attached a video. Getting pretty good at figuring that out.

This is normal, you have warm water exiting the exaust, and emptying into cooler water, some vapor will be present.
Feel the riser tops if they are very warm to the touch there maybe some circulation issues within the risers..clogging up.
Some times at an idle the seawater pump doesn't pump as much thru those risers and some vapor will be present.
If you bring up the RPMs they may cool more.
Your seawater pump maybe getting ready for a new impeller, if you've not changed it out in a few years, do so.
The vapor isn't smoke unless it's blue, or black.
Not seeing that in your video.
SV Cloud Duster

[Cadence]

Originally Posted by inspectr

Second the use of a stethoscope to localise a noise source
I used a 600mm length of hose and a small plastic funnel jammed in one end to synchronise twin SU carbys on my old 1962 MGA 1600 MK2 sports car - worked better than any other professional tool to get the sound of the air intakes exactly the same

Sounds like the joys of SU carbs.

[Montanan]

Glad getting a stethoscope aided in audibly identifying the noisy bit, and now that you have that in your kit, you are ready to play doctor.

All the best.

Dan

[cshep215]

Originally Posted by Boatyarddog

This is normal, you have warm water exiting the exaust, and emptying into cooler water, some vapor will be present.
Feel the riser tops if they are very warm to the touch there maybe some circulation issues within the risers..clogging up.
Some times at an idle the seawater pump doesn't pump as much thru those risers and some vapor will be present.
If you bring up the RPMs they may cool more.
Your seawater pump maybe getting ready for a new impeller, if you've not changed it out in a few years, do so.
The vapor isn't smoke unless it's blue, or black.
Not seeing that in your video.
SV Cloud Duster

One of the marina technicians was walking by and saw the issue. He suggested changing out the exhaust bellows and servicing the the lower unit. I have the bellows on order and will be ordering a new impeller kit and changing the gear lube.

The starboard riser is warmer to the touch than the port side. I have replaced both manifolds in the last three years but not the risers and elbows. (That will be this winters project). I was concerned there might be a clog but when I pulled the plug to see, a very good flow of water drained out and it was clean. No signs of dirt or rust. I will say the starboard manifold was a Sierra and is 3 years old. The port side manifold was replaced just last year with a Mercruiser part and not an after market and stays quite cool. I have heard good things about Sierra parts, just curious if they don’t channel water through as good as a Mercruiser part.

[Slacktime]

Could it be the bilge pump running dry with a stuck float switch?

[rbthorson]

Mercruisers have a bearing in the gimbal housing. It could be making noise if there is insufficient grease. Some models have a grease fitting on the starboard side of the gimbal housing on the outside of the transom below the waterline. It could also be that the engine is misaligned with the gimbal housing which can damage the engine coupler. Engine alignment should be checked every time an engine is installed.

[Boatyarddog]

Originally Posted by rbthorson

Mercruisers have a bearing in the gimbal housing. It could be making noise if there is insufficient grease. Some models have a grease fitting on the starboard side of the gimbal housing on the outside of the transom below the waterline. It could also be that the engine is misaligned with the gimbal housing which can damage the engine coupler. Engine alignment should be checked every time an engine is installed.

Please refer to post #20, he seems to have located the noise.
Gimbal bearings "rumble" at higher RPMs.
Replaced a lot of those, I've not heard them "whine" though.
SV Cloud Duster