squealing noise from aft

reycuban · #1 (**permalink**) 12-30-2008

Hi, I have an 1988 Catalina 30 which has been recently upgraded and refitted. Off and on during the last couple of days we are hearing a squealing noise aft,like a loose belt. It seems to come on when in gear over 1200 RPM's.The steering mechanism and gear and throttle cables were just serviced a couple of weeks ago, checked and everything seem OK. Mechanic on vacation until jan 5th. Any ideas? Thanks.

fullkeel7 · #2 (**permalink**) 12-30-2008

reycuban, if it sounds like belt squeal, probably is. Quick check...while the engine is NOT running, with a rag placed over the alternator pulley cooling fins, try to rotate the pulley. If you can, it's too loose. If not I'd check for misalignment. At any rate, if there is any belt slipage/wear, there is usually some rubber dust from the belt on the surrounding area. Good luck.

reycuban · #3 (**permalink**) 12-30-2008

Thanks. First thing I did, belt is OK. Altenator and belt were replaced a month ago.

AllThumbs · #4 (**permalink**) 12-30-2008

Cutlass bearing too dry?

CaptainFredGreenfield · #5 (**permalink**) 12-30-2008

Spray the pulley and belt with Belt-eze or a small amount of WD-40. If it goes away, problem solved, lubricate properly with belt-eze. Could be a waterpump shaft if it was a cutlass bearing it would sound much further aft I reckon. Let us know what you find!

camaraderie · #6 (**permalink**) 12-30-2008

Did you re-adjust the tension on the aternator belt severa weeks later after installing?
Perhaps you have your packing gland too tight...are you getting a couple of drops a minute when in gear?

reycuban · #7 (**permalink**) 12-30-2008

Thanks. The noise is coming from aft, below the binnacle area? The stuffing box was serviced in August, so the cutlass bearing should be OK? I hope.
As I mentioned the noise is off and on and only

when in gear at higher RPM's.
Was planning to cruise for the holidays, should I postpone until mechanic arrives? Thanks for the help.

fullkeel7 · #8 (**permalink**) 12-30-2008

or...shaft packing too tight? Still, if the belt hasn't been adjusted since replacement and you have around 3/4" deflection(engine manual might have belt deflection limits), I'd give it a tweek. New belts will stretch a bit in the first few hours of use. Just don't over do it, over tensioning is bad on pulley and alternator bearings. There's another source, alternator bearings will sometimes squeal if dry. Might try opening the engine compartment and have a helper try to duplicate the rpm and load while you try to isolate the source of squeal.

Yeah, what Cam and Fred said, jeezh, I type slow!

reycuban · #9 (**permalink**) 12-31-2008

Alternator is new,just replaced. Belt is tight,no give. Opened engine hatch while running and no noise from engine, it sounds like is coming from aft. I suspect the cutlass bearing as suggested, but the stuffing box was serviced last August and checked. By the way, the noise is not constant,went for a day without it and goes away if I drop below 1200 RPM's.
Will check stuffing box again, if OK, I think will wait for mechanic. Thanks a lot for the help.

Boasun · #10 (**permalink**) 12-31-2008

Had that happen on one vessel... Turned out to be a harmonic when the shaft is turning at a low RPM. Check the shaft for straightness and its alignment with the Cutlass bearing.