intermittent whistle or whine

[Tug-N-OK]

My captain Ken passed from this life 18 months ago so I am now solo on my R21EC. I remember that he told me freezing weather was hard on the HydroHoist lift so I take my tug out whenever the temperature is above 40 and the wind less than 15, which is several times a week. It is my solace. There are no marine diesel mechanics on our lake but fortunately Tim who assisted my husband is still available to help me.

Last November I ran over a nylon ski line that wrapped around my propeller so tightly that Tim had to remove the prop to get it loose only to discover 3 of the 4 blades on the propeller were bent and the propeller anode missing; however, the driveshaft looked OK. While the prop was sent to Propellers by Nettle in Texas for repair, I decided to see if there was any preventive maintenance that should be done. Was there ever… it is apparently not enough to just add fuel and occasionally check the oil! I am constantly learning all the things Ken did that I didn’t even see. When Tim tried to remove the gearbox dipstick, it was on so tight that it broke and the oil was so low it didn’t measure on the dipstick. We replaced the oil and dipstick. When the prop was returned (it looked great!), Tim had to bore the replacement zinc because it didn’t line up. There appeared to be no problems in neutral or low rpm, but when I took my tug out, I heard a high pitched whine at higher rpm. I must admit that I had not been aware of the sounds my engine made before this experience so do not know if that whine had always been there. He removed the propeller zinc but still had the whine. He found 4 13mm bolts from the shaft to motor were loose as well as the belt and tightened them. It now only whined at about 2100 rpm. Since I had the same whine with or without the propeller zinc, he replaced it.

I was back in business for several months, just choosing to go at less than 2100 rpm. Then in early March when I put the tug in gear to pull out of the slip, I heard a long thumping sound and immediately put it in neutral. Tim happened to be on the dock, so we lifted the tug out of the water and sure enough I had bent my prop again, just 2 blades this time. Although they do an excellent job, Propellers by Nettle do not offer a frequent bender discount! Apparently the tailwind had pushed my tug forward so that the prop caught on the boatlift supports. I now push the tug to the back of the slip to be sure the prop is clear before I put the engine in gear! Since weather in Oklahoma can be unpredictable, I winterized my tug and sent the prop off to be repaired.

I had to have surgery so was unable to take my tug out for over a month. When I could finally take her out, it was a beautiful day and I was so excited that I forgot I had winterized her and did not check the seacock (it was closed) and even worse, did not check that water was coming out. I had been out quite a while when I noticed the Overheat light was on, I never heard an alarm. I made another mistake: I turned around and headed home instead of immediately turning her off. I did call Tim to alert him that I would need some help. He had me stop the engine, wait 15 minutes, and then try to start it again. The engine started but the light came on immediately. He had me stop the engine and came to tow me back to the dock. The impeller was badly damaged, melted and possibly some pieces missing, but the oil was clear so he felt I had not done serious damage. He replaced the impeller. When I took her out again, I noticed an intermittent whistle and whine. Tim believes the sound is coming from the impeller area. He removed the impeller and verified that it was inserted the correct direction and used more glycerin, but the intermittent whistle or whine remains, never in neutral but at different rpm.

I’ve looked through the posts and am concerned that pieces of my impeller may have gotten into the heat exchanger. I carefully watch the overheat light now and have had no further problems. Since there is no marine diesel mechanic to check my tug, what do you recommend that I do?

 

[daveo]

First, I am sorry for the loss of Ken. My wife and I are looking forward to many cruises when I retire.
Since no one else has replied, I will give my suggestions. I have a 25 and on it, I can increase engine speed without having it in gear. On the side of my throttle control, there is a black rubber pad. If you push in, where the throttle lever pivots, you can feel a little button go in. You can then increase engine RPMs, without shifting into gear. I would do this out in open water, just to be safe. When / if you can increase engine RPMs, see if you have the whine at 2100 RPMs. This can help determine where the whine is coming from. You said the transmission was low on oil. I wonder if you have a bad transmission bearing? It could be on the engine side, which would still whine with the engine but if it is on the propeller side, you would not have the whine. If it is the transmission whining, a temporary fix, would be to use a heavier oil. It might help. Any way you look or should I say listen, you will eventually need an experienced mechanic. Good luck.

 

[Tug-N-OK]

Thanks so much, Daveo, your suggestion was very helpful! I revved the engine in neutral and did not have the whine or whistle. Verified multiple times that the whistle occurred in gear but not in neutral, even at high RPMs. My helper Tim said that the gear oil was low, but not off the stick as I had stated. I am contacting the marine repair shop here on the lake to see if they will trouble shoot a transmission problem on a diesel and trying to find the nearest repair shop that will work on diesels. Again thanks for your help! Libbye

 

[daveo]

Libbye,

Working on a transmission should be cheaper than working on the engine. You said that you bent the propeller twice. Another place your whine could be coming from or causing problems in the transmission is your propeller shaft. If you search "cutlass shaft" on this site, you will find a lot of talk about the shaft / bearing. You very well could have a bent shaft that wobbles at high speed causing issues with the cutlass bearing and or transmission.
I would run the engine at slow speed and look for vibration of the engine. Then run at 2200 and look for vibration. I could say "touch" the engine also, but be careful of what you touch, temperature and moving parts wise.

 

[Tug-N-OK]

Thanks for the search tip!! It led me to lots of good information including some about prop fouling, which was the beginning of this problem. When Ken and I bought our Tug, we joined the US Power Squadron and took advantage of all their classes including Engine Maintenance. At the time I thought Ken would always be there and trusted his knowledge too much, but I don’t remember ever hearing about cutlass bearings! I did know the term “fouling” but simply forgot it when I tried to search for help. I really appreciate your patience in explaining the basic stuff to me! Libbye

 

[SGIDAVE]

Hello Libbye,

I'm sorry for the loss of Ken. And I'm glad to hear you continue to use the boat - that's a REALLY good thing.

Comments on vibration and random thoughts about possible consequences of propeller damage from prop strike/s...

The 3 cylinder diesels in our R21's normally vibrate at idle...say around 800-1000 rpm. Lift the engine box whilst at idle and see the engine shaking...that's all normal. Now slowly rev the engine (in neutral, for safety), and see the majority of the engine's vibration disappear above 1200-1400 rpm.

I suspect you have a bent shaft and/or worn cutlass bearing. If your shaft-transmission coupler bolts had become loose, that indicates excess vibration. When you have a propeller strike, there is also a chance the shaft has been damaged (bent) too. The vibration from the slightly bent shaft will prematurely wear the cutlass bearing thus making the vibrations worse. Or, perhaps there is an alignment issue with the propeller shaft and the cutlass bearing which has caused the cutlass bearing to wear out early....several possibilities or combinations of possibilities. It's GOOD you have eliminated the engine as the source of the 'whine' by revving whilst in neutral.

You should also check the engine mounting bolts/nuts for proper tightness in light of your current problems. Too much vibration can loosen them; catastrophic prop strikes (like when the propeller hits something at say 2000 rpm and stalls the engine kind of prop strike) can damage the mounts. I don't know your specifics of propeller strikes...I'm NOT saying your boat has endured a catastrophic prop strike. Look them over good.

/dave

 

[Tug-N-OK]

Thanks for your advice, Dave! After the initial fouling, the engine mounting bolts were loose and have been tightened. I do not notice excessive vibration, just the whine. Several folks looked at the shaft and did not think it looked damaged; however I am planning to take my Tug out of the water to check the cutlass bearing as I haven’t checked that.

My dilemma now is do I risk major damage to my Tug if I continue using it, just adjusting the RPMs to minimize or eliminate the whine? Another concern is being out solo and having the problem escalate so that I cannot return to the dock. Do I need to find an experienced mechanic immediately or can I enjoy my Tug until a convenient time or some new symptom? Libbye

 

[SGIDAVE]

My dilemma now is do I risk major damage to my Tug if I continue using it, just adjusting the RPMs to minimize or eliminate the whine? Another concern is being out solo and having the problem escalate so that I cannot return to the dock. Do I need to find an experienced mechanic immediately or can I enjoy my Tug until a convenient time or some new symptom? Libbye

Hello Libbye,

Given that the whine is NOT from the engine proper but more likely the transmission-shaft-bearing-propeller part of the system, I think there is minimal risk of "major damage" with continued "gentle" use of the tug. Ensure the engine and transmission have adequate fluids...and enjoy.

Hopefully you can get the whine fixed without major pain (i.e., financial and/or significant 'down time' of the boat) soon.

/dave

 

[Tug-N-OK]

THANKS! I will find an experienced marine mechanic and take the Tug in for a thorough check when I take a trip later this summer. I’ll let you know the pain level! 😀