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Old 01-03-2012, 08:12 AM   #1
Lt. JG

 
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Default Squealing coming from Engine Bay

I am getting real sick of this boat. (Admittedly this problem was caused by me!)


1999, 1900SR with 5.0L Alpha

I am getting a high pitched squealing noise from the engine bay once the engine has warmed up, usually not straight away from a cold start.


Background is that I forgot to put the drain plug/bung in a month or so ago, so filled the stern with a fair bit of water, was a couple of inches up the sump. Apart from shorting out a few wires, the squealing started the same day, after I pulled the boat out of the water again and drained, then put back in the water.


As mentioned, squealing usually doesnt start straight away, but after about 15 minutes of running. When I cut the motor, the squealing slowly fades out, so to me indicates noise is not coming directly from the engine itself but from another moving part coming off the engine.


Any ideas? I have tried spraying some Inox/ lubricant on the starter motor pinion, as was suggested by my local mechanic, but didnt seem to do much, either because I couldnt get it on there properly, or it isnt the cause.

Im pretty much thinking this is going to be an expensive fix, but hopefully not.

Help!


Andrew
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Old 01-03-2012, 10:40 AM   #2
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This may seem overly simple but maybe all you might need to do is replace or tighten the fan belt.Also, take a look at belt pullys that might have developed a rust spot from the bilge water.
Good luck and happy New Year.
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Old 01-03-2012, 11:25 AM   #3
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Cool squealing

The way I track down sounds from engine is a 3-4 foot hose put one end to your ear and then to each bearing in hyd pump , water pump ,alternator etc works for me .
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Old 01-03-2012, 01:02 PM   #4
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high pitched squealing noise is usally a bearing after it heats up. start with the alternator and/or the belt tighter pully, power steering pump, raw water pump etc.

spray some WD-40 on the pully and belt, and see if that helps. The good news is a bearing will get louder and the squeeky wheel gets the grease.

off change you got the gimbel bearing wett, and it needs to be greased.
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Old 01-03-2012, 03:05 PM   #5
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Andrew,

You state that the squealing slowly fades AFTER you cut the engine. Roughly how long does it take between the moment of engine shut down and when the squealing stops?

Is the engine carb'd or fuel injected? Does it have fresh water cooling or raw water cooling?

I think you have a pressure build up associated with the engine warming up, and a slight leak that is manifesting itself as a squeal. As things cool, and the leak relieves the pressure, the squeal stops.

Dan
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Old 01-03-2012, 10:18 PM   #6
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Thanks All for responses.

Pretty sure its not the belt, as is not coming from the front of the engine bay, its from the back. Not a belt squeal either, more metal on metal.

Where do I grease the Gimbal bearing from again? I did recently get the boat serviced after the noise started, I asked them to chcek the Gimbal bearing as I thought it had gone, but it was apparnetly still ok. They also didnt hear the noise, but obviously didnt run it long enough to get the noise to start.

The noise runs on for another 1-2 seconds after the engine has completely stopped, the noise lowers in volume over this time.

Engine is carbed, I recently put a new intake and carb on, I was at first worried about an air leak, but havent been able to find one. Interestingly though, this has reminded me of something, which I had not related to the squealing. I was testing the vaccuum of the intake just after the squealing first started. Engine was running and squealing, I took off the breather hose from Rocker cover to bottom of Carby to hook up vaccuum hose. The engine revved up, and squealing mysteriously disappeared. I havent tried this again since, but could well be a leak which is causing this.

Engine is Raw water cooled.


Andrew
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Old 01-04-2012, 01:53 PM   #7
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Given that the noise continues on after the engine is shut down suggests the noise is not mechanical in nature.

When the key is turned off the engine, power steering pump, water pump, and anything else driven off the engine - including the output shaft, coupler, outdrive input shaft, through the gimbal bearing to the out drive and the gears inside the drive, all stop turning immediately. There isn't anything I can think of that "free-wheels" for a couple of seconds after shut down.

Dan
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Old 01-04-2012, 02:13 PM   #8
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you know, it could be as simple as a collapsed raw water or other pipe squeezing from a restriction.
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Old 01-06-2012, 08:10 PM   #9
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Ok, had the boat out yesterday afternoon, started squealing as usual. Then one of the breather hoses popped off the rocker cover, the squealing stopped, replaced by a sucking air sound, obviously the air being sucked into the hose by engine. I popped the seat up and played around a little.

With 1 breather hose off, the engine revs up slightly.
As soon as breather hose hooked up again, squealing starts, revs die back to normal.

Ive also just had a bit of a brain wave, I think with OEM carb, it was connected to only 1 Rocker cover breather, whereas I now have both rocker covers connected to the carby.

Is the engine sucking so much air through the breathers, it is creating a buildup of vaccuum? Has this been harmful? Any suggestions as to what I should do, ie. leave 1 rocker cover hooked up to carby, other put a filter or something on it, or run the hose into the bilge blower or something?

Ive never seen anything like this, the noise made is pretty horrendous considering this is the cause, and I fear I may have done something to the motor.

Andrew
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Old 01-07-2012, 07:40 AM   #10
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Update

I have had a bit of a look at the manual, and realized what an idiot I am!

I had both breathers from Rocker covers hooked to bottom of carb, instead of having one that vented fresh air into the block. I will remedy by putting an air filter on one of the breathers, and hook the PCv to the carb again. PCv is clean so is operating ok.

I have retuned again with this change, was idling very low, and adjusted timing slightly, and will give it a run tomorrow.


Andrew
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