"Howling" Hydreco!

[MikeP]

Three years ago I rebuilt my Starboard Hydreco tranny pump to correct a minor pressure issue. At the time I bought two rebuild kits, intending to rebuild the port just to maintain symmetry. But I never did it...until today.

I discovered that a howling noise that I have heard periodically on the boat, and mistook for everything from cutlass bearings to turbo bearings (all checked and found OK), was the port tranny pump. Actually, the pump itself doesn't make any noise but the spin-on filter head for the tranny is mounted on the aluminum shelf assembly that supports the 4 ac compressors. The vibration in the hydraulic line sets up a harmonic in the shelf that howls! I unbolted the filter assy from the shelf, letting it hang free, and the howl disappeared.

Interestingly, I have heard that howling for years and, the first time I heard it was at WOT and I thought it might be a turbo but it continued howling at idle and then disappeared. So I pretty much ignored it. It did it again periodically over the years but this morning was the first time I seriously tried to find what was causing the noise. You can feel the vibration in the pump's output hose.

I disassembled the pump, figuring I might see something that could cause the vibration but everything looks great though the seals and O rings are old/hard. I frankly don't know if a leaking/seeping seal could cause the vibration but I'll put the new kit in anyway, as I had intended to do 3 years ago.

If if doesn't reduce/eliminate the howl, I'll shock mount the filter assembly which will eliminate the noise. The starboard pump hose has the same vibration as far as frequency but it is noticeably less powerful so obviously there is something slightly different internally. Bushings/rotors look great with no scoring or play.

After discovering the cause, I did some on-line research and discovered that hydraulic pumps are well known for inducing noises, including buzzes, knocking, screams, etc in parts they are attached to and there are a variety of solutions including changing the pump design, using a combination of hose/hard pipe, and shock mounting various components.

 

[YBbroke]

Three years ago I rebuilt my Starboard Hydreco tranny pump to correct a minor pressure issue. At the time I bought two rebuild kits, intending to rebuild the port just to maintain symmetry. But I never did it...until today.

I discovered that a howling noise that I have heard periodically on the boat, and mistook for everything from cutlass bearings to turbo bearings (all checked and found OK), was the port tranny pump. Actually, the pump itself doesn't make any noise but the spin-on filter head for the tranny is mounted on the aluminum shelf assembly that supports the 4 ac compressors. The vibration in the hydraulic line sets up a harmonic in the shelf that howls! I unbolted the filter assy from the shelf, letting it hang free, and the howl disappeared.

Interestingly, I have heard that howling for years and, the first time I heard it was at WOT and I thought it might be a turbo but it continued howling at idle and then disappeared. So I pretty much ignored it. It did it again periodically over the years but this morning was the first time I seriously tried to find what was causing the noise. You can feel the vibration in the pump's output hose.

I disassembled the pump, figuring I might see something that could cause the vibration but everything looks great though the seals and O rings are old/hard. I frankly don't know if a leaking/seeping seal could cause the vibration but I'll put the new kit in anyway, as I had intended to do 3 years ago.

If if doesn't reduce/eliminate the howl, I'll shock mount the filter assembly which will eliminate the noise. The starboard pump hose has the same vibration as far as frequency but it is noticeably less powerful so obviously there is something slightly different internally. Bushings/rotors look great with no scoring or play.

After discovering the cause, I did some on-line research and discovered that hydraulic pumps are well known for inducing noises, including buzzes, knocking, screams, etc in parts they are attached to and there are a variety of solutions including changing the pump design, using a combination of hose/hard pipe, and shock mounting various components.

I'm sorry for being immature.......but that last paragraph is borderline X rated.

 

[SeaEric]

I'm sorry for being immature.......but that last paragraph is borderline X rated.

It's no fun when you can't hear them scream.

I'm hoping that some day I will have the time to truly bond with my boat and have the kind of fulfilling relationship that MikeP has with his boat. It sure is fun reading his posts.

 

[Avenger]

Some Unknown Comic Said....

I got a sweater for Christmas... I was hoping for a moaner or a screamer.

 

[jim rosenthal]

I suppose as moderator I should edit these, but honestly I'm too busy trying to figure out how to convince people I don't know any of you folks.

 

[rwappleton]

It's the minds that need editing. Good luck with that one!

Scroddy, You are just too funny!!!!!!!!!!!!!!

 

[MikeP]

Surprised the heck out of me but the rebuild kit - which contains seals, Orings, and a couple of very odd-shaped gaskets/seals - reduced the vibration in the pressure line so there is no longer any sympathetic vibration - howling - from the shelf assembly. I believe that what happened was that the new parts in the rebuild kit reduced the end play in the pump rotors. Prior to disassembly there was a slight bit of end play - I didn't measure it so I can't say how much. Now there is none. So maybe that end play caused the excessive vibration...I don't know. In any case, now the vibration in the pressure line is much less than what it was, about the same as the other tranny. No more howling!

 

[Avenger]

Oh sure, it's all my fault for quoting some comic..... meanwhile who started it by talking about howling trannies?

For future reference it's a TRANSMISSION. A tranny is something completely different.

Maybe a pictorial representation will help.

Tranny:

Transmission:

See the difference?

Thanks to Sky for this quote from another thread.

 

[Boatsb]

Oh sure, it's all my fault for quoting some comic..... meanwhile who started it by talking about howling trannies?

For future reference it's a TRANSMISSION. A tranny is something completely different.




Thanks to Sky for this quote from another thread.

Which of the above would you use at the drag races?

 

[SeaEric]

Which of the above would you use at the drag races?

It depends on whether you're in Key West, or elsewhere.

 

[SKYCHENEY]

Hmmm. Good question.

 

[Regal2800]

Mike, i also have a real low whine/howl from my boat which i only hear at real low speeds once i place the gear in neutral. as the boat slows down to around 4mph i hear the howel. Kind of sounds like when you rub your finger around the tip of a glass beer bottle. once the boat slows to 2mph or so it goes away. I thought it was the cutlass bearings but your post is making me wonder if maybe its the hydreco? Does yours do it while underway or does it do it at the dock? Can you hear it from the engine room?

 

[MikeP]

Prior to yesterdays rebuild of the tranny pump, it would randomly do it at any speed/RPM, including sitting at the dock. The pitch of the vibration did not change based on engine speed. It started a couple of seasons ago, only occurring occasionally but began occurring more often. It was quite audible in the engine room and in the passageway as you walked past the ER. It was quite loud in the passageway abeam the aft ER door on our 53 and faded as you walked past, toward the master stateroom. It was also clearly audible at the helm at certain times.

Do you have remote-mounted filters? If not, I don't think any audible noise would be generated by the pump. It's a function of the filter head being mounted on a something that acts like a soundboard and makes the vibration inherent in the pump audible.

As I said earlier, since the vibration was greatly reduced by the rebuild kit, I think the end play of the rotors has some effect on the level of vibration. That's really the only thing that changed internally in the pump.

Since the pump pressure doesn't seem to change based on eng speed, that would explain why the eng RPM doesn't change the vibration frequency. NOTE that I'm talking about PUMP pressure, NOT tranny pressure, which is what your helm gauge reads. Perhaps the vibration is related to the pressure relief valve in the pump...I don't know.