Mercruiser 4.3 Belts

trailshredder

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Replacing both belts on my 87 Mercruiser 4.3L. I went to NAPA for the belts but one they gave me looks real short compared to what was on there. I then began wondering if the previous owner had the wrong belt on and routed wrong. The alternator Belt went around the crank, water pump and alternator. The power steering belt went around the crank, water pump and power steering. Is that correct? It looks like the shorter belt they sold me might fit either the crank to alternator or water pump to alternator. The crank and water pump pulleys both have "V's" for 2 belts.
 

Don S

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Re: Mercruiser 4.3 Belts

What's the Merc serial number of your engine? That is the ONLY way to know for sure what engine you really have.
 

trailshredder

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Re: Mercruiser 4.3 Belts

What's the Merc serial number of your engine? That is the ONLY way to know for sure what engine you really have.

Stupid Question .... Where the heck is the serial number stamped on the engine?
 

Bondo

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Re: Mercruiser 4.3 Belts

Stupid Question .... Where the heck is the serial number stamped on the engine?

Ayuh,... On a little aluminum tag riveted to the block, just above the starter, usually hidden by the manifold,...
 

Don S

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Re: Mercruiser 4.3 Belts

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Bayou Dave

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Re: Mercruiser 4.3 Belts

For my 1987 4.3L 175hp I got these 2 belts from iboats and they fit perfectly. #15440 & #15570
 

trailshredder

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Re: Mercruiser 4.3 Belts

That is a block casting number, not a Merc SN. Do you see the picture I posted of where the tag is?

yeah, that is exactly where this number was. So there will be a tag instead of a casted number? I am just not finding it, was pretty much upside down over the back seats trying to find it! lol
 

trailshredder

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Re: Mercruiser 4.3 Belts

Found a decal on the valve cover that was painted over .... that number is 0B677096 and another decal on the valve cover reads B529369.
 

Don S

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Re: Mercruiser 4.3 Belts

The 0B677096 is for your outdrive, the 0B529369 is for your engine, and it's a 205, not a 175 or 185. See what I mean about choices other than 1987 4.3L ;)

Anyway, you have a 205 (4bbl carb) If you type in your serial number in this link https://webapps.brunswick.com/literature/literatureSearch.do it will take you to the OEM part numbers for your engine.
But you still aren't done, there is two different power steering pump brackets, and the stamped bracket has 2 different belts depending on pulley size.
Alternator belt (found in the intake and front covers) also has different belt choices that you can check on your engine.
 

trailshredder

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Re: Mercruiser 4.3 Belts

This helps a bunch Don, Thanks! What assembly did you find the alternator belt? I can only locate the power steering belt.
 

Don S

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Re: Mercruiser 4.3 Belts

This helps a bunch Don, Thanks! What assembly did you find the alternator belt? I can only locate the power steering belt.

You must not have read the last sentence of my previous reply.
 

trailshredder

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Re: Mercruiser 4.3 Belts

Sorry, thought you meant there will be a number that cross referenced which belt. Thanks again!
 
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