Volvo Saildrive noise

[kipwrite]

Volvo D2-75f with 150S-C saildrive, about 1800 hours.

Has developed a prop rpm related tapping noise in forward, reverse, and neutral when the prop spins. Sounds worse in reverse. Depending on engine rpm, it's even or has sort of a rhythmic beat.

No vibrations. Engine runs smoothly and quietly.

Boat has a flex o fold 3 blade prop.

Had a diver check the anodes, and the prop, all snug. When the driver spun the prop with the engine off, we could hear the tapping noise.

The tapping is noticeable with the engine off, sailing, before the prop is folded. Sounds to us like one tap per rotation.

Sail drive oil clean and at the right level.

Have had the seals replaced once on this saildrive. Bearings original.

Boat will be hauled shortly, but wondering if anyone has had a similar experience and what the cause/solution was.

Will post what we find, hopefully in the next week or so.

Kipwrite

[tkeithlu]

Sorry that you've gotten no respnse/thoughts.

I tried narrowing down the source in my mind. The problem is that it could be in either of two zones. One is the propeller and shaft, and the other is the second half of the transmission, given it occurs when the transmission turns in neutral.

Can you disconnect the shaft and spin it? The propeller-shaft zone is more likely and also the less worrisome - you really don't want to discover that you lost a nut in the tranny.

I'm hoping for and betting on something hitting the shaft or coupling on rotation, or something just loose enough around the prop to feel tight but not really be.

[tkeithlu]

Sorry - I was thinking shaft and propeller, not saildrive. Same basic idea holds.

[Pete7]

Do you have a rope cutter on the sail drive?

Pete

[Oldwheels]

Mechanical things that start making noise do not heal themselves well.

[kipwrite]

No rope cutter.
Thanks for the responses.
Boat scheduled to be hauled shortly. Will post update once we figure it out.
I'm thinking an anode is slightly loose and that was missed by the diver. Or maybe even the bolt holding the prop on.
Doesn't sound like a bad bearing, those usually groan instead of tap. A broken gear tooth wouldn't sound different forward/reverse, and might not set up a off beat rhythm at certain rpm's.

[tkeithlu]

I'm glad to hear that you are pulling the boat.

When you think about whether some part or other (your prop?) is loose, remember that you have a 75 HP engine. "Loose" is two very different concepts when you (diver) try to move it with your one-person no -lever arm, versus throwing 75 HP at it. "Tight" means tight according to your torque wrench.

[kipwrite]

Pulled the boat. Noise (upon spinning the prop in neutral) seems to be coming from the top of the saildrive near the rubber gasket.

Pulled the oil plug and the oil was filled with metal shards.

Tech going to dig in a bit further, but seems like a bearing or something has disintegrated. Drive had run several hours with a fair amount of metal bits floating around -

[ohthetrees]

In my opinion, if the oil is full of metal bits, the drive is a write off. I recently tried to have a Volvo 150S with metal flakes in the oil rebuilt, and the four shops I called were not interested in the doing the work once they heard about the metal flakes.

In my case the root cause was a leaky input shaft seal installed by the previous owner by a shade tree mechanic in the South Pacific, then the delivery crew running the saildrive dry as they delivered it to me. I don’t blame them, they didn’t know there was a serious leak in the saildrive. So even if they checked the oil on departure, it could’ve been damaged in just a few hours.

In my case it was a bit difficult to bring myself to replace it, because the drive was operating seemingly perfectly despite the metal flakes, no noises and smooth but since we were departing for an international cruise, I felt it was best to replace it before we ran into trouble.

If you do manage to get rebuilt, I’d like to hear how it goes, and how much it costs.

[kipwrite]

I think I might be coming to the same conclusion, as the labor to rebuild might be prohibitive.

Saildrive has been well cared for since new.

All that said, I'd like to find out which part disintegrated.

This occurred during my recent passage south. Not too many hours running on metal-filled oil, but I can see how rebuilding a saildrive run with metal shavings would be very worrisome over time.

[belizesailor]

Originally Posted by kipwrite

I think I might be coming to the same conclusion, as the labor to rebuild might be prohibitive.

Saildrive has been well cared for since new.

All that said, I'd like to find out which part disintegrated.

This occurred during my recent passage south. Not too many hours running on metal-filled oil, but I can see how rebuilding a saildrive run with metal shavings would be very worrisome over time.

A friend of mine who is a factory trained Volvo tech with many years of experience attended a training class on sail drives. During the class they tore down and rebuilt sail drives many times. This requires specialized tools + specialized parts + specialized skills to do it right = $$$'s.

At the end of the training they were all sitting around discussing sail drives and rebuild vs replace, their conclusion was it is better to replace because rebuilding a badly damaged sail drive properly will cost similar to new and the results wont be equal to new.