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Squealing from Engine Compartment, Could a raw water pump shaft bend?


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Hi All, I have a squeling from my engine compartment. If I spray a bit of PB plaster or other lubricant on the shaft of the raw water pump it instantly dissapears. I rebuilt the pump this weekend with new bearings, impeller, and seals and it still squeals. When I was rebuilding I noticed a 1mm or less runout on the shaft when spinning it. Quite visible actually. I am wondering how this thing could have bent? It seems to me the squealing could be from the bearings getting jerked around by this bent shaft. Boat has 1400 hours on it. I ended up ordering a new raw water pump from skidim and a new belt, so I will test those this weekend. I also replaced the alternator and that did not cause the squeal.

Could it be something else? With a new alternator, belt, and pump if it still squeals then the only thing it could be is the engine water pump correct? How hard is that to replace?

 

Edited by 95echelon
typo
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1 minute ago, wdr said:

Belt tension or lack of more precisely immediately comes to mind.

Could be it. I thought I got it pretty good when I replaced the alternator. Ugh, I could have been chasing ghosts this whole time! But i guess after 1400 hours having a new alternator and a new raw water pump is good insurance. And I will now have backups of all this at my lake place #weekendsavers

Any tips on tightening the belt tension for the alternator?

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Are you sure your alternator bracket bolts are in good condition?  They can shear.  There's an updated alternator bracket to address this.

I wonder if you had seized an older bearing at one point and spun the shaft a bit.  That's the only way I can figure there'd be any bend in the shaft.  Even with that, I'd have expected the soft brass of the housing to give way first.

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12 minutes ago, UWSkier said:

Are you sure your alternator bracket bolts are in good condition?  They can shear.  There's an updated alternator bracket to address this.

I wonder if you had seized an older bearing at one point and spun the shaft a bit.  That's the only way I can figure there'd be any bend in the shaft.  Even with that, I'd have expected the soft brass of the housing to give way first.

I just redid the bolts and bracket and they were in good shape, But I can look again. Any link on the updated bracket? I am going to do a full tune up as well. I have the week off next week.

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7 hours ago, 95echelon said:

Could be it. I thought I got it pretty good when I replaced the alternator. Ugh, I could have been chasing ghosts this whole time! But i guess after 1400 hours having a new alternator and a new raw water pump is good insurance. And I will now have backups of all this at my lake place #weekendsavers

Any tips on tightening the belt tension for the alternator?

Old school process was to have about no more than 1/2” of deflection on the longest open span of belt.

Edited by wdr
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Pull the impeller and run it for a few seconds to make sure it is the bearings.  It doesn't make sense that they would squeal if they are new.  My money is on the impeller running against the cover plate.

My pump never has run true, but the shaft is straight.  The pulley flange is the bad part on it.  I think the hole was drilled a little off, or maybe the face was ground wrong.

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18 hours ago, 95echelon said:

Hi All, ....................

Could it be something else? With a new alternator, belt, and pump if it still squeals then the only thing it could be is the engine water pump correct? How hard is that to replace?

 

The engine circulation pump on a direct drive is pretty easy to swap out.   The marine version has a bronze impeller.  They usually leak water out of a weep hole when they go bad.
 

You could loosen the belt and spin it by hand to See how it feels. But Your problem is probably something the others identified .

 

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On 6/22/2020 at 8:33 PM, justgary said:

My pump never has run true, but the shaft is straight.  The pulley flange is the bad part on it.  I think the hole was drilled a little off, or maybe the face was ground wrong.

Mine too.  I had to remove it once and didn't get it into the right holes and it wobbled even more.  Since it only has 3 Allen screws, I had a 50/50 shot of getting it right; reinstalled and was back to "normal."

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