Mysterious noise while motoring

[Al Smith]

At the end of last season, our '84 CD33 began making a grinding/knocking noise while motoring in gear. It seemed to radiate towards the starboard side of the boat and could be heard very well at the navigation station, although one could also hear it well in the cockpit. At first I thought that I may have wrapped something around the shaft or that the shaft zinc might have loosened, so I dove on her to check. The water in the Chesapeake is really cold in late October!!! Nothing was visibly wrong, but I scraped a very few small barnacles from the prop and motored below the RPM (1800) where the sound was most noticeable. I checked the alignment and the stuffing box but both seem fine.

Now that the boat is out of the water, I rechecked the shaft and there is no looseness at the cutlass bearing, but there is a grinding noise when the prop is turned clockwise, and small pieces of thin black rubber move with the shaft and seem to get stuck and dragged a little. The shaft and cutlass bearing were replaced right before we bought the boat four years ago, and she has seen only relatively light use since we have had her. Can this be a bad bearing at this stage, or should I look further? The stuffing box was dripping a little bit more than usual at the end of the season, but seemed to be OK.

Thanks for your input.

Al Smith



saylr@adelphia.net

[Bill]

At the end of last season, our '84 CD33 began making a grinding/knocking noise while motoring in gear. It seemed to radiate towards the starboard side of the boat and could be heard very well at the navigation station, although one could also hear it well in the cockpit. At first I thought that I may have wrapped something around the shaft or that the shaft zinc might have loosened, so I dove on her to check. The water in the Chesapeake is really cold in late October!!! Nothing was visibly wrong, but I scraped a very few small barnacles from the prop and motored below the RPM (1800) where the sound was most noticeable. I checked the alignment and the stuffing box but both seem fine.

Now that the boat is out of the water, I rechecked the shaft and there is no looseness at the cutlass bearing, but there is a grinding noise when the prop is turned clockwise, and small pieces of thin black rubber move with the shaft and seem to get stuck and dragged a little. The shaft and cutlass bearing were replaced right before we bought the boat four years ago, and she has seen only relatively light use since we have had her. Can this be a bad bearing at this stage, or should I look further? The stuffing box was dripping a little bit more than usual at the end of the season, but seemed to be OK.

Thanks for your input.

Al Smith

Al, I'd take a good look at the engine mounting bolts. I found
a couple were loose on my CD22D. Then realign if necessary.



wtclark@datasync.com

[zeida cecilia-mendez]

Al: I own a 1982 CD-33. I am also baffled by a similar "grinding" noise but only as I put the throttle in the higher speeds, between the 1800 and 2500 rpms. It has been driving me insane for the past couple of years. I also had the yard replace the cutless bearing when I first got the boat four years ago. However, the engine was never re-aligned after that. During my second year with the boat, the tranny died. I had to take it out and replace all the major parts, it is now like new, and I have had the engine aligned (or so I think)... but the grinding noise is still there... I could swear it may be something with the cutless. I feel it most under my feet as I stand by the wheel, driving the boat. You can hear it distinctly. I have had a diver check for any movement on the shaft... nothing! I myself have gone in the water to check ... Everything looks OK down there... My boat will be going out of the water next month for regular bottom maintenance, and I will be replacing the cutless again, this time, myself, to make sure it is done correctly. Then I will align the engine after the boat is back on the water a couple of days... If the noise disappears then, what a relief it will be. I know what you are going through, since I've been dealing with this same mystery for quite a while now. My engine is a Universal diesel model 30 #5424 three cylinders and I kind of keep it in good shape; always starts at first try, etc., with a 1" Bronze prop shaft, Hurth 100 transmission. I have checked everything and everywhere I thought could be making the noise, and every time come up empty handed. So for peace of mind, I will have a new cutless by end of Feb. If this proves to be the culprit, I will let you know.

Zeida Cecilia-Mendez



zcecil@attglobal.net

[John R.]

Zeida's points are right on the mark. CUTLESS. Especially in your case if you are truly seeing small pieces of black material (rubber spline shavings or particles)at the end of the stern tube. Contrary to seemingly popular belief a prop shaft does not have to feel loose or move to indicate a damaged/bad cutless bearing. A looseness will develop if the cutless wears to a great degree; however prior to that point it may be very snug without any play because the shaft is traversing the length of the cutless at an angle relative to the axis of the supporting rubber splines. That will cause binding and result in noise and/or vibration. Until those splines are severly worn there will be no free play (looseness of the shaft). This is usually a result of engine/coupler, flexible coupler or universal joint misalignment in a boat that has a stern tube incorporating a cutless like the CD. Other boats that utilize struts can have a problem with strut alignment also being a contributing factor.

At the end of last season, our '84 CD33 began making a grinding/knocking noise while motoring in gear. It seemed to radiate towards the starboard side of the boat and could be heard very well at the navigation station, although one could also hear it well in the cockpit. At first I thought that I may have wrapped something around the shaft or that the shaft zinc might have loosened, so I dove on her to check. The water in the Chesapeake is really cold in late October!!! Nothing was visibly wrong, but I scraped a very few small barnacles from the prop and motored below the RPM (1800) where the sound was most noticeable. I checked the alignment and the stuffing box but both seem fine.

Now that the boat is out of the water, I rechecked the shaft and there is no looseness at the cutlass bearing, but there is a grinding noise when the prop is turned clockwise, and small pieces of thin black rubber move with the shaft and seem to get stuck and dragged a little. The shaft and cutlass bearing were replaced right before we bought the boat four years ago, and she has seen only relatively light use since we have had her. Can this be a bad bearing at this stage, or should I look further? The stuffing box was dripping a little bit more than usual at the end of the season, but seemed to be OK.

Thanks for your input.

Al Smith

[Warren Kaplan]

I can't help you with your problem exactly but a couple of times when I had some confusing engine problems I had my diesel mechanic hop aboard and I took him for a short ride. He nailed the problem every time in about 5 minutes. That's what I'd do. While you drive the boat the mechanic can have and ear down below in the engine compartment. He didn't even charge me because he got to do the repair work. Its another way to go if you can't find the problem yourself.

Warren Kaplan
S/V Sine Qua Non
CD27



Setsail728@aol.com

[Brian]

I second Bill's comments on the engine mounts. Our 33 had transmission problems for years. There was vibration and a bit of noise that didn't seem right. We had a transmission replaced, only to have it go bad the next year. This happened three times. Each time we told them to check the mounts. Each time they said they seemed fine. I wasn't until we repowered this season that the gentleman who put the new engine in noted that the engine mounts were fine, but the threads they were bolted into on the engine bed were stripped. This made the engine 'bounce' on the engine bed, banging up the transmission, cutless bearing, etc. may not be the cause of your problem, but do check the engine is 'secure' in its bed. perhaps it was a general problem on 33s.

Brian

Al, I'd take a good look at the engine mounting bolts. I found
a couple were loose on my CD22D. Then realign if necessary.

[JimL]

....about ten years ago I was looking for a family power boat to use coastal. I went and talked to the Coast Guard fellas' (Ventura) and they told me their number one cause of "tow in" or "rescue" of small boats was motor mounts! They said that most power boats have the mounts lag bolted into on-edge wood stringers. When boats are slammed on the quarter or side by waves, the weight of the engine tries to keep going sideways while the boat stops. On sterndrive powerboats, the bolts shear sideways through the stringers and the engine drops onto it's pan....which opens a leak at the transom...which is unfortunate because the bilge pump was under the pan and is now SMASHED FLAT! They told me to only buy a boat with through bolted motor mounts (I found a Sea Ray made that way). Anyway, sailboat motors shouldn't be susceptible to as much hammering...theoretically....but I've broken an outboard mount in Mexico, and cracked an outboard bracket in Colorado....just from falling off waves. Brian's post is really good food for thought!

[Al Smith]

....about ten years ago I was looking for a family power boat to use coastal. I went and talked to the Coast Guard fellas' (Ventura) and they told me their number one cause of "tow in" or "rescue" of small boats was motor mounts! They said that most power boats have the mounts lag bolted into on-edge wood stringers. When boats are slammed on the quarter or side by waves, the weight of the engine tries to keep going sideways while the boat stops. On sterndrive powerboats, the bolts shear sideways through the stringers and the engine drops onto it's pan....which opens a leak at the transom...which is unfortunate because the bilge pump was under the pan and is now SMASHED FLAT! They told me to only buy a boat with through bolted motor mounts (I found a Sea Ray made that way). Anyway, sailboat motors shouldn't be susceptible to as much hammering...theoretically....but I've broken an outboard mount in Mexico, and cracked an outboard bracket in Colorado....just from falling off waves. Brian's post is really good food for thought!

Thanks everyone for all your great thoughts and comments. I'll have the cutlass bearing replaced this winter and check the motor mounts myself, then have the mechanic (fortunately, I do have access to a good one, albeit a little high) realign the engine after she's in the water. I'll let you all know how things go. Thanks again.

Al



saylr@adelphia.net