High Pitched Whine

[JerryRoss]

I have developed a loud, high pitched whine at 1600-2100 rpm but not at other rpms. This began immediately after my new bottom job which may be a coincidence. However, my prop and shaft were thoroughly cleaned and painted with a primer and two heavy coats of hard bottom paint. Until this bottom job at 767 engine hours I never had any whine. Any thoughts would be appreciated.

[wolfe10]

Jerry,

Be sure the air is purged from the stuffing box water circuit. It is water-cooled!

Also, make sure that the engine thru hull is open and that water is coming out the exhaust.

Brett

[JerryRoss]

Brett,

Thanks for the tips but I might have a different system than you. I have a dripless shaft seal that has water input from the raw water pump and the water input hose has an anti-siphon break. I removed the water input hose from the dripless seal and got a pencil size stream of water flowing out of the dripless seal. I allowed about one cup water to gush out. I assume the water was coming through the cutlass bearing and up the shaft tunnel. There does not appear to be any way for the water to enter the shaft tunnel except through the cutlass bearing.. It seems that was too much water flow to be coming through a properly fitting cutlass bearing but I maybe wrong. I did not check my shaft or cutlass bearing for play when I recently hauled out for a bottom job which was dumb. However, during previous prop cleanings in the water, I never noticed any side play but was never looking for that either so it may have been there, just not noticed. Based on various cutlass bearing posts and the pictures below, I appear to have a black nylon cutlass bearing. After I drained the one cup water from the dripless seal, I still had the high pitch whine at 1600-2100 rpm. Any more thoughts from you or others would be appreciated.

[R.B.]

I guess before you can diagnose the problem you need to figure out where it is coming from. Use a mechanics stethascope to try and pinpoint the areas that may cause the whine. eg. dripless seal, transmission, alternator, water pump etc. Look for telltale signs of wear, extra dust around the engine, fluid leaks, rusty areas etc.

Good luck, hope you find the problem!

[wolfe10]

Any time the boat has been out of the water, it is not a bad idea to check engine alignment AFTER it has been back in the water for a few days. A mis-alignment of engine/shaft could cause a vibration OR noise.

Not difficult to do-- if you want the "blow by blow" instructions, let us know.

Brett

[JerryRoss]

Brett,

I would certainly like to have your engine alignment instructions. That will be my next project but can't do until early June. Any thoughs about the the water flow rate I had through my dripless seal. It seems high to me. My email is jerryross07@cs.com. Thanks in advance for the alignment instructions. Will let you know what I find.

[KenKrawford]

Jerry, why not give PYI a call and ask them (800-523-7558). I'm sure they'd have a pretty good idea if you problem might be related to the cutlass bearing.

Brett,

Any thoughs about the the water flow rate I had through my dripless seal. It seems high to me. My email is jerryross07@cs.com. Thanks in advance for the alignment instructions. Will let you know what I find.

[wolfe10]

Brett,

I would certainly like to have your engine alignment instructions. That will be my next project but can't do until early June.

Jerry, et al;

As with many technical discussions, it is a lot harder to explain than to do. If possible, copy and read this through while looking at the engine mounts and coupling area.

Buy a long (10" is a good length) or a couple of short .002" (that is 2/1000") feeler gauges at an auto parts house. They are VERY thin, so it is not uncommon for one to tear.

Remove the ladder and access the front of the engine. Move the aft cabin mattresses out to the main saloon and access the prop shaft area. Transmission in neutral, engine off and cold-- no reason to get hot doing this.

Remove the bolts holding transmission output shaft coupling to prop shaft coupling. Separate a little by hand and clean both surfaces. If rusted together, may have to tap on them to separate. A rag and WD40 will clean them if not too rusty. Sandpaper and then WD40 if rusted. Basically, you want to measure metal to metal clearance, NOT rust buildup.

Bring the couplings back together. Make a mark on the couplings so you can measure clearance all around the circumference as you rotate the couplings. You can install one of the bolts so the couplings rotate together, but do not tighten a nut on the bolt. This just insures that the couplings can be rotated together.

With the couplings clean and brought together, they will touch (i.e. zero clearance) somewhere-- could be at the top, a side, bottom, etc. This will give you a rough idea of how you need to move the engine (adjust engine mounts) to move the transmission coupling away from that tight area. Because out of spec could be caused either by an alignment issue or any variance in the coupling surfaces, the most accurate measurement is to take those same marks on the couplings and rotate them by hand, trying to insert the thin feeler gauge as you go around the circle. By determining where it is tightest/loosest, you can decide what needs to be adjusted.

Because, for example, raising the front of the engine and lowering the rear of the engine would have the same affect on angle, you need to determine whether the transmission coupling needs to go up or down/ left or right so the couplings line up top to bottom, side to side. Said another way, the angles could be perfect but the transmission coupling could be (as an exaggeration) 1" higher, but absolutely parallel to the prop shaft coupling. That is why you need to basically determine if the two couplings are aligned vertically/horizontally. If they are not, your adjustments to being the angle between them to zero should also include top/bottom, left/right adjustment.

When properly aligned, the two couplings will be in alignment top/bottom, left right AND you will not be able to insert the feeler gauge anywhere as you rotate them around all 360 degrees.

Adjustments can be made by raising or lowering the front or back of the engine on the threaded engine mount bolts. Also by loosening the bolts that hold the engine mounts to the stringers, you can use the elongated hole to move the mounts left/right.

Finally torquing down the two engine mount bolts securing each engine mount to the engine stringer. BTW, THESE NEED TO BE TIGHTENED PERIODICALLY. I don't have specific torque values, but snug them up so the mounts don't move on the stringers.

As I said, once you have done this, you will say, "Boy, that was a lot easier than that long description".

Brett

[JerryRoss]

Brett,

Your engine alignment instructions are great. You did a fantastic job describing the spatial alignment needed and how to achieve it. This will become a permanent part of my maintenance kit. Thanks a million. I'm out-of-touch for the next two weeks and it will be about three weeks before I can check my alignment and pursue other tips given me in this forum. I will let you all know what I find.

[JerryRoss]

I finally solved my high pitch whine problem which began immediately after my last bottom job. The whine was from the propeller and caused by the bottom paint on the outside edge of the prop. After checking everything possible including the dripless seal and transmission to prop shaft alignment, I called Catalina and spoke with Jim McNamara. After listening to my problem description and everything I had checked, Jim said it was probably prop whine due to paint on the outer ½ inch of the prop blades. Jim said prop whine was not uncommon and that some yards put tape on the outer edge of the blades when painting the prop. After removing paint from the outer edges of my prop blades, the whine is gone. Many thanks to Jim and Catalina. Also, thanks to all fourm members who gave me tips.

[TBOT422]

Jerry,

Was the whine you noticed coming from the prop turning while under sail? I have always had a whirr when sailing above 3 knots coming from the prop. It was my audible reminder to put the transmission in reverse to keep the prop from spinning and wearing the shaft seals and bearings when they're not needed.

[JerryRoss]

Gary,

My prop whine was only when motoring or motorsailing and only in the 1600-1900 rpm range. There was no whine in reverse, none with the prop engaged when tied to the dock, and was not affected by having the sails up or down. When motoring, if I rapidly increased rpm from below 1600 to somewhere in the 1600-2100 range, the whine would not begin until the boat speed stabilized at whatever rpm I had selected. There was never any whine when just sailing and I do not afways remember to shift into reverse when sailing.