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Discussion in 'Gas Engines/Drives/Transmissions/Props' started by msballin, Oct 3, 2017.
No photos but appears to have shreaded between the threads....somewhat akin to spaghetti strips.
Hmmm..circulating pump pulley spun freely, raw water pump did not spin freely (I've been told because of tightly fitting impeller in the housing) but was able to turn it, alternator pulley spun freely and crankshaft pulley not at all (which I'm told is normal)
So, had yard mechanic take a look at what appeared to be a bearing noise (screaming type sound different than a squealing sound of a bad or loose belt) as the rpms increased approaching 2000 rpms. I also noticed upon physical inspection of the exhaust elbows, the port side elbow was noticably hottler than that of starboard. One other visual observation was after changing the belt, the raw water exhaust was pumping at a rate greater than I ever observed. This was not to be seen upon the next observation.
All that said, the yard mechanic suggested the screacing noise was possibly coming from the resonator in the raw water exhaust hose (decided to check this because of the higher temp of the elbow0 and mentioned nothing about the bearings. Curious about this. Your thoughts? Continued thx for all of your contributions.
The only thing you really haven't checked properly is the raw water pump. Pull it off, remove the impeller and see if the pulley turns freely with no grinding.
So I have the facts straight.....was the belt two years ago shredded in the same fashion?
Squealing sound: Belt slipping
Chirping sound: Misalignment of an accessory drive pulley
Frayed belt edge: Misalignment of an accessory drive pulley
Polished belt edges: Belt slipping
Glazed belt grooves: Belt slipping
Fluid contamination: Oil, power steering, or coolant leak
Excessive cracking: Other than severe old age, defective tensioner
Whirring sound: defective bearing in tensioner pulley or idler pulley
Rhythmic noises occurring at engine speed: Delaminating belt backing, chunking of belt ridges, or foreign object embedded in belt groove
Grinding sound: damaged bearings in driven accessory
Belt coming off: Pulley misalignment, belt misalignment on pulley, defective tensioner, or bearing wear in tensioner, idler or driven accessories
Shredding is a result of the belt getting too hot.
Makes complete sense. Regrettably, I can't physically get to that raw water pump. I'm a handy guy...but know my limitations. I'm hopeful the yard mechanics are good...as I've never used them before and my personal mechanic is not permitted on the grounds. Guess we will see. Curious about your or anyone else's opinion regarding the resonator in the raw water exhaust causing this noise. Mechanic felt because one side was much hotter than the other this may be the culprit. Personally, I would think a bad or failing raw water pump may produce this issue..but then again, I'm not a mechanic. Manifolds, elbows and risers were done 2 seasons ago with OEM parts. Got 7 years out of the priors. Thx
Belt two years ago shredded as a result of the idler/tensioner pulley locking up. Pulley broke apart and as a result the belt shredded. When and prior to this belt shredding there were none of the sounds present as described above. Only after I reinstalled the new belt did the grinding/screaching metal on metal sound appear.
As mentioned in another part of this thread, Curious about your or anyone else's opinion regarding the resonator in the raw water exhaust causing this noise. Mechanic felt because one side was much hotter than the other this may be the culprit. Personally, I would think a bad or failing raw water pump may produce this issue..but then again, I'm not a mechanic. Manifolds, elbows and risers were done 2 seasons ago with OEM parts. Got 7 years out of the priors. Thx
Mine shredded this past summer after replacing 2 days earlier. Solution was to make sure that all the "crud"..... overheated rubber particles were cleaned out of the little grooves on all pulleys after it overheated and shredded. Then the next belt will ride securely without slipping off and shredding again. I used a toothbrush and a lot of pieces came out.
Great advice! I did exactly the same on the reinstall of this present one. Though I can not vouch as to whether or not this procedure was followed on the prior belt.
One other visual observation was after changing the belt, the raw water exhaust was pumping at a rate greater than I ever observed. This was not to be seen upon the next observation.
I think this is pointing you in the direction of the problem....if there is a noticeable reduction in the cooling water being discharged and the exhaust elbow is running hotter than normal there is something wrong with the pump bearing or the impeller or you have a blockage in the exhaust or restricted water intake.....right after I bought my boat I had an impeller break apart from age and lock up the pump and shred the belt....luckily the bearing and the pump were in good condition....there were no unusual sounds from the pump prior to this happening...
Sounds eerily familiar. Do you think this could have had anything to do with the inability to throttle up and the vibrations I felt?
no....the engine is very powerful and will continue to spin the crankshaft pulley even if another pulley becomes tight or locked up....the belt will try to slip at first but as it is forced to slide over a stationary pulley it will heat up and become soft and will shred or break or come off of the pulley....there is no way that drag on the belt from a bad pulley is enough to slow down or drag an engine to keep it from revving without destroying the belt first....
Your engines are fresh water cooled (meaning the engine and lower part of the manifolds have coolant in them). It is possible for the raw water impeller to disintegrate and block a cooling path in the heat exchanger or a riser. If this has happened, that would explain why one riser is hotter than the other. For the sake of facts, buy a $35 infrared thermometer and post the temp readings. Use the other engine as a baseline.
The other explanation is that something is wrong with that side of the engine. I don't think it is the resonator.
the more I think about this I am stating to suspect an issue with the transmission....by thinking about all of the symptoms you posted it may be possible that a problem with the transmission caused the engine to not throttle up and could be the source of the sounds you heard and the vibrations you felt but this would not be the cause of the engine belt getting shredded...I think you still have an issue with the cooling system on that engine which is a separate issue....
are you experiencing any issue with the transmission for that engine?
is it possible you have something wrapped around the prop or prop shaft that would put drag on the tranny/engine?
A little info for you,
Some people have reported here that one riser is warmer than the other. I think that the final conclusion was that this is a normal condition for these engines.
Ok...so here's the latest update...and an interesting one at that. Turns out the noise (squeal/screech) was not from either pump.a A well trained ear from a mechanic felt it was coming from raw water exhaust so he pulled the large hose and fiberglass elbow from between the hose and exiting from the collector muffler and discovered two things; the interior of the hose was coming apart and the fiberglass on the inside of the elbow and collector was coming apart from the inside at the opening of both parts. If any of you have played a saxaphone or clarined or are familiar with where the sound eminates from while playing reeded instrument, you'll understand that the screeching was born from the air/water being forced through the damaged exhaust as described above. The remainder of the exhaust will now be disassembled to make sure these parts have not experienced the same. I'm now thinking that the rumble/vibration I experienced may have actually come from the flapping of of rubber from the inside of the exhaust hose. It was explained to me that the deterioration of the fiberglass from the collector and elbow happens as a result of extremely hot water going through it. Though it was also explained that one overheat would likely not have caused this much damage. Apparently, this may have been going on for a while. I've owned the boat for nine seasons and have only had a mild overheat as a result of a shredded belt 2 seasons ago...not sure about years prior to my ownership.
RE: the cause of the overheat..I'm back to thinking it was the result of the rusted crankshaft pulley. Will have raw water impeller and housing changed regardless...it's time for its 2 year replacement.
The exhaust collector had been ordered and when all is back together I'll report back. Thanks again for all of your input. Been a good learning experience for this guy. A fined weekend wished to you all.
Pardon a couple of typos...
so he pulled the large hose and connected fiberglass elbow forward from the elbow/riser and exiting back from the collector muffler and discovered two things
Yes, that has also been my experience. However, in this case the heat is abnormally hot....skin burning hot.
I hopes this resolves your issues....these type things help all of us learn.....I had never had this happen and have never heard of this happening so it is always good to learn new things....
keep us posted....
That makes two of us! Will look forward to reporting back positive news. Cheers!