Singing noise coming from throttles

peterkvs

Active Member
Nov 11, 2012
511
Guntersville, Alabama
Boat Info
400 Sundancer 1999
Engines
3116 Cats, 1000 hours
Hi,

I've been the proud owner of a 400DA since the end of Novermber 2012. I really love this boat and because I have been handed down the dreaded DIY curse from my father I am presently spending more hours tinkering than boating. But it's still winter and just maybe i will be able to get ahead of the maintenance and little issues before spring. Haha. Anyway, I've had the boat out on the nice days and done some cruising I I've heard a singing noise that seemed to come from the dashboard. But I just dismissed it as a reflected noise. Kind of sounds like a turbo whine. However, today I realized that if I put my hand on the throttle housing that the noise was deadened a lot, and so I have realized that this singing noise is coming from the throttles. I did a search on such a problem, but came up empty. Anyone know what is causing this? The only thing I can think is that the tach cables from the Glendinning Sychronizer are somehow coupling noise into the throttle cables.Maybe a bad bearing in the sync? It works fine. Noise is definately related to engine RPM. Only strange thing is that it is MUCH less noticible when the transmission is in neutral. Any ideas or thoughts would be great. Thanks! Peter
icon6.png
 
I suspect you are hearing either the turbo whine or a transmission noise. Try cracking the engine hatch under way and see if you can confirm the noise when you hear the engines. The 3116 turbos are noisy, but the cable jackets usually give you enough insulation to abate the noise to a manageable point. See if you can identify which lever the noise is coming from........my bet is it is the transmission levers since the throttles pass thru the synchronizer, but if it is in the throttle quadrant, most likely one of the cables is in a bind where it attaches to the throttle lever under the control.

Another possible cause of the noise is the transmissions. Your engines both turn the same direction so counter-rotation of the props is achieved by turning one transmission backwards. There are a different number of clutch plates in reverse than in forward, so the reverse transmission usually makes a little more noise, but that is usually only noticeable at lower rpms and goes away as engine speeds get to roughly 1200-1500rpm.......and that sound is definitely telegraphed thru the shift cable. Not to scare you to death but you could be hearing an internal transmission noise. The Hurth 800 series transmissions will sometimes give up the ghost with bad or disintegrating bearings, usually on the port side. A quick way to tell is to run the boat with the hatch open while you are in the bilge where you can hear the noise, which is usually a rumble or rattle, not a whine. You might also change the fluid on the transmissions, keep the drained fluid separate, and strain it to look for ferrous metal particles in the old fluid......when you pump the fluid out, open and drain the transmission sump in a shallow pan.....1/2" pipe plug at the very bottom of the transmission case on the port side of both transmissions........ and inspect that last pint of fluid for metal particles as well. Hopefully, you won't have any metal in the fluid, but if you do, a lot of ferrous (magnetic) particles indicate a pending bearing failure or wearing shaft.

You are close to me and depending upon where the boat is located, I might know someone who can give it a listen for you........where is the boat located?

Good luck with it............
 
Could be from the propellers.

The unusual noise emanating from what is known as a “singing” propeller is the direct result of the vibration of the blades. These are disturbed by the irregular hydrodynamic actions of cavitation and vortex shedding and induced by the extreme variations in the wake.

Sharpen or "chisel" the blade edges to fix.
 
Guys,

Thanks for the responses. The noise in definately coming from the throttle housing. If I place my hand on the housing it reduces it a lot. I listened to is again today and realized it really sounds like an old spedometer cable going bad. Perhaps it is just noise coupling into the cables. Next time I am out I will try and see if I shut down one motor if I can isolate the noise to a single motor. I will also see if being in gear makes a difference. May disconnect the sync cables if thats not too hard.

Frank, Thanks for the detailed reply. I had a Cat mechanic working on the boat today adjusting the valves, and injectors. He thought it all sounded great, but he's not really a Marine guy. The boat is located on Lake Guntersville at Alred Marina if you are familiar with that. Having someone put an ear to it would be great. As long as they don't hear anything bad. Lol. Since you mention transmissions I'll throw this in. After the top tune up today I took the boat out. The tech said to run it hard and accelerate hard and see if the engines were smooth and evenly powered. While moving at about 6 kts I pushed the throttles most of the way up pretty quickly, the boat lept forward and really dug in to the water. I was impressed for about three seconds until the boat started to violently shake. I pulled the throttles back quickly and the shaking stopped. Then I heard a bang. Really figured i screwed something up. (Later I figured out the bang was the water from behind slamming the swimdeck ladder cover open against the back of the boat.) After that event I drove the boat less aggressively and it all seemed fine. WOT at 2800 rpm and 28.5 kts. Smooth. I am hoping what I experienced was just cavitation or something else benign. Thoughts. I am going to be changing all the fluids over the next month. When the Cat Tech was out I had him take samples of the Oil, Coolant and Trans fluid.

Thanks,

Pete
 
Pete
i have the exact "whine" coming from the shift lever housing in my 400DA. A couple of things I did to isolate it:
I ran the boat at various load settings each engine independently
Ran the boat at various load settings with sync on and off.
listened to the transmissions with a stethoscope.
I have the trans oil analyzed each engine oil change and I always cut up and inspect the filters looking for metallics.

here is what I surmise:
the noise is being transmitted up the port transmission shift cable and originates in the port tranny. Certain frequencies transmit well through mechanical elements and this may be just one of those cases. As Mr Webster iludes the port transmission is running essentially in reverse and consequently runs against the counter-shaft which would create a gear whine. Consider the noise your automobile makes when running in reverse and against the reversing gear set. Now my port transmission was replaced in 2009 from the Hurth 800IV to the stronger ZF 85IV due to bearing failure in the counter shaft which is not that uncommon so keep an eye on the oil; it's best to repair than replace. Regardless, the replacement makes the same noise.
 
ttmott, Thanks for the reply. I will check out the gear shift lever too. How many hours were on your transmission when it died? What were the signs?

Thanks,

Pete
 
A minor point.........when the bearing fails in the Hurth 800, you have already run years with metal shavings in the transmission from the disintegrating bearing and race. This transmission has an internal hydraulic pump, lines, galleries, etc. and the internals are all lubricated by the transmission fluid, which by the time the bearing failed had about a cup of filings in it. After seeing the handfull of garbage that collected in the transmission sump, I never considered rebuilding the transmission because I didn't feel we could ever get all the shavings out of the hydraulic system, we knew we had 900± hours of wear on the clutches, gears and other bearings, getting a transmission out of one of these boats is a job, and rebuilt transmissions had little or no warranty support behind them. I decided to replace the Hurth with the new design ZF-85IV since I only want to go thru a transmission replacement once.

and, Pete, you cannot take the synchonizer out of the system .......follow the cables from the pump on the engine to the one that goes up under the helm and you'll see why. The synchronizer is mechanical and its control box is in the middle of the cable run so you cannot effectively remove cables from it and still operate the boat. Additionally, I am no where near Guntersville, but I do know of an excellent independent diesel technician in the area. Ask anyone with a diesel boat and they will know of him and I bet your marina has his contact info.....Diesel Don.
 
Last edited:
Frank's point is very valid, however, correct me if I'm wrong but isn't the trans filter before the hydraulic pump consequently the trash would not really get through the hyd system except to the filter? Or, is looking at the filter a waste of time?

Regardless, the PO had to bear the brunt on the transmission change in my boat ($16K with some other work being done also) - my reference is from the invoices, the survey, and P/N on the transmission. As documented there was 1200 hours on the engine when they changed the trans. From the invoice description there was a lot of vibration and major grinding noise from the Hurth.
 
There is a filter and I don't know the partical size it traps. This got down to a $ decision for me.........new transmission @ $4700 or a remanned one for $3475. The labor was the same either way. I couldn't find anyone in NW Fla with experience who would rebuild the old transmission and warranty it, so for $1200 more money, I chose to buy the new, stronger ZF-85 series transmission. I built a frame to straddle the engine/transmission with a trolley to get the transmission to the center of the bilge. That reduced the labor involved in the R&R. In fact, we had the engine jacked up and the transmission out and on the floor in the shop in about 2 hours. My total cost for the replacement was under $7K, but I was the mechanic's helper. The work isn't technically challenging, but ZF requires professional installation to validate the warranty.
 
There is a filter and I don't know the partical size it traps. This got down to a $ decision for me.........new transmission @ $4700 or a remanned one for $3475. The labor was the same either way. I couldn't find anyone in NW Fla with experience who would rebuild the old transmission and warranty it, so for $1200 more money, I chose to buy the new, stronger ZF-85 series transmission. I built a frame to straddle the engine/transmission with a trolley to get the transmission to the center of the bilge. That reduced the labor involved in the R&R. In fact, we had the engine jacked up and the transmission out and on the floor in the shop in about 2 hours. My total cost for the replacement was under $7K, but I was the mechanic's helper. The work isn't technically challenging, but ZF requires professional installation to validate the warranty.

yup logical and much less risk.

I re-read the original post and the noise is coming from the throttles not the shifters which changes, most likely, the source. First, I would stick my head in under the helm in the breaker panel and listen. Is the noise louder in there; the cables are routed up through this access. The synchronizer is not that complicated but it does have gears in it. The port throttle cable runs directly to the port engine's fuel injecTion pump. The port engine has a tach drive mounted to the harmonic balancer and the engine's RPM is provided through a cable to the sync (the gold box mounted on the ER's forward bulkhead. The starboard engine also has an identical tach drive routed to the sync but geared to rotate reverse of the port one. The starboard engine's throttle cable is only routed to the sync and the starboard helm throttle cable is only routed to the sync. So, the port engine is the master and directly linked to the throttle lever. When the sync is not activated the starboard helm throttle cable is directly connected to the starboard engine's injector pump and the throttle operates same as the port. Inside of sync gold Box are two counter rotating worm gears which are driven by the tach drive cables. Between the worm gears is a spur gear assembly that when there is differential between the two engine revs moves either left or right in the housing. This spur gear drags the starboard engine's throttle cable and either increases or decreases the power setting of that engine to match the rpm of the port engine. There is an electrical solenoid that either engages the helm throttle cable to the starboard engine's throttle (de-energized) or engages the spur gear movement to the starboard engine's throttle cable (energized). So in short, there a series of rotating cables and gears that may be making noise. You can easily remove the sync's cover plate and do a visual inspection to start with. Next I would disconnect the tach drive cables from the little drive gears mounted at each harmonic damper and run the boat to determine if the noise is coming from all of these rotating parts. I would caution to make sure to disconnect both as should the sync activate the spur gear will be driven har to one side and possibly be damaged. Also do not attempt to remove the little gear drives from the engine as they require a special tool to align. So, from this it's a process of deduction if the noise goes away when the cables are disconnected.

tom
 
Frank,

Thanks for the info. I meant disconnect the tach cables from the synchronizer to see if that was where my noise was coming from.

I have heard of Diesel Don. I hope I never need him, but good to know he is there and competent.

Regards,

Pete
 
Tom,

Thanks for the info. My synchronizer syncs the engines pretty close, but I can do better manually. Is there some other adjustment inside other than the clutch screw that would be used to fine tune the RPM delta? Also, I just had a Cat mechanic do the valves and injector set up. But he had to remove the sync cables from the front of the motor to turn the engine with a wrench. So he had to eyeball the sync tach cables. He checked them with the engine running and said they were running true, but I don't know how true. Is this a problem or will it be? He also said one of the right angle drives was tilted down a bit. That cant be good either. My biggest problem is me, at 6'7" I can't get to the front of the engines and be sure I can get back out. Thoughts?
 
Tom,

Thanks for the info. My synchronizer syncs the engines pretty close, but I can do better manually. Is there some other adjustment inside other than the clutch screw that would be used to fine tune the RPM delta? Also, I just had a Cat mechanic do the valves and injector set up. But he had to remove the sync cables from the front of the motor to turn the engine with a wrench. So he had to eyeball the sync tach cables. He checked them with the engine running and said they were running true, but I don't know how true. Is this a problem or will it be? He also said one of the right angle drives was tilted down a bit. That cant be good either. My biggest problem is me, at 6'7" I can't get to the front of the engines and be sure I can get back out. Thoughts?

To my knowledge (and that not saying a lot) there are no other adjustments than the clutch and positioning of the microswitch stops. If you go to the Glendinning web site the manual is available. Regarding the cable drives there are two adjustments: centering and spacing. The four fasteners that attach the mounting plate to the engine block can be loosened to adjust the centering and the jamb nuts on the gear drives adjust the spacing (obviously). To do this without the tool, which I have done, is to space so there is 1/8" free play in and out for the little drive spindle and set the location of the mounting plate so the drive spindle is visually centered both laterally and vertically and freely moves in and out using your fingers. You really need to do these adjustments without the drive cables attached so it's not "preloaded" by the cable. If you are going to do this I would order a set of now spindals as these are wear items and do break. If the drive is "tilted down" then the spindle is not driving in alignment between the bracket in the harmonic balancer and little gear; needs to be fixed. Lastly, when you are in there if you can fold up that many times to get in pump some grease into the drive gears.
 
Thanks. I'll take a closer look at the sync cable drives, or have a smaller friend do it. Lol. I got my Oil Sample reports back on the transmissions and they are good and clean. So hopefully there is no issue there yet.

Thanks Again,

Pete
 
Really good news on the oil. BTW make sure not to chince out on the oil quality for those trannies and watch closely for any foam or signs of water in it (ie leaking cooler); shift only at less than 1000 RPM and lastly make sure your shift cables are adjusted to fully engage the transmission shift mechanism both reverse and forward (if not fully engaged the clutch packs may not get full hydraulic pressure and so long clutches).

Regarding the noise - in further retrospect unless the tach cables are making the noise, I don't believe it from the Sync system. I still think the port trans is the culpret like mine....
 

Forum statistics

Threads
112,948
Messages
1,422,824
Members
60,930
Latest member
Ebrown69
Back
Top