How to tighten alternator belt? 1987 Mercruiser 230.....help?

clattin

Petty Officer 3rd Class
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Jul 18, 2012
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New boat owner and the alternator belt on my Mercruiser 230 seems loose (about 1" of deflection) and really whines at idle speeds.

I have the manual for the motor and it shows that I need to loosen 4 bolts and then rotate the alternator in order to tighten the belt. How do I keep tension on the alternator while I'm tightening the bolts? Could I hook a ratchet strap to the alternator to pull the belt tight and then re-tighten the bolts?

Thanks!
Chris
 

Oshkosh1

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Jun 8, 2009
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968
Re: How to tighten alternator belt? 1987 Mercruiser 230.....help?

Two cold ones and a helper.:D
 

wellcraft-classic210

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Sep 22, 2010
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Re: How to tighten alternator belt? 1987 Mercruiser 230.....help?

Yes / or you can pry on it ( gently! ) with something & then tighten it.


1 note
If you pulleys are rusty you may need to do it more often & the sides of the belts can wear to the point of no longer being wide enough to grab properly even when tight.

I tried using the POR15 process to save some pulleys that were rusty & pitted with excellent results.
 

clattin

Petty Officer 3rd Class
Joined
Jul 18, 2012
Messages
89
Re: How to tighten alternator belt? 1987 Mercruiser 230.....help?

Got it....tried to have my wife help me and tighten the bolts as I applied tension to the alternator, but she wasn't really able to do it so I used a ratchet strap to the bottom of the alternator and hooked it to the trailer. Worked great.

I wasn't able to see/get to all the different bolts that the manual identified that I need to loosen. I just loosened the bolts at the top and bottom of the alternator and it seemed to let me get enough tension on the belt. Anyway, it doesn't squeal anymore!

Thanks!
Chris
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: How to tighten alternator belt? 1987 Mercruiser 230.....help?

I used a ratchet strap to the bottom of the alternator and hooked it to the trailer. Worked great


How does it stay afloat with a hole that big thru the hull????? Anything more than hand pressure to tighten belts will lead to bearing failure in the water pump, power steering pump, and alt.
If your squealing belts:
there loose
worn too thin
worn away from rust
hi battery charge rate
 

81 Checkmate

Lieutenant
Joined
Jul 20, 2010
Messages
1,360
Re: How to tighten alternator belt? 1987 Mercruiser 230.....help?

I think what the Doctor is asking........ There is a reason your belt has started squeling...

Need to check the following... as he described.

Most likely your pulleys are rusting in the V- Groove and wearing the belt out/ thinning it and causing it to stretch.

Just a thought!
 
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