Replacement belt size?

[KD4UPL]

I thought I got the right replacement serpentine belt for my engine but it doesn't fit. Upon closer inspection of all the ordering guides I can't seem to find my combination at all.
I have a 2004 Mag 350 Bravo 3, S/N 0W005823. It has power steering and standard cooling (it sucks in lake water thru the engine).
The old belt is 57-863876-3. The new belt I ended up with that is just a bit small is an 18-15102. Can somebody please direct me to the correct belt for this engine?
Thanks,

 

[alldodge]

The old was 8638763 and new is 865615Q03

The Sierra 18-14102 (105 inch x 13/16) crosses to 865615Q06 (note the 06) which is for a Alpha/Bravo with closed cooling

Dayco belt
104.5 inch 7 rib (13/16) = 5071045
Note 507 for type and 7 ribs and 1045 for the length

Could use Dayco, Gates and go find the length you need
Dayco #
5071055 = 105.5 length
5071065 = 106.5 length

To find the length of you current belt lay on a floor and mark the belt and the floor. Now roll the belt on its back until the mark comes in contact with the floor again. Mark and measure the distance

 

[stang32]

the 507 only has 5 ribs. i have made this mistake several times, always forget the correct #

 

[KD4UPL]

Thanks,
So if the 865615Q03 is the one I need then that's over $120 just for a belt. I don't buy that many serpentine belts but I wasn't expecting that. I know the belts for my Chevrolet Suburban and Impala are more like $30 to $50.
I was going to replace the one on the boat just as a precaution; I don't know how old it is, I've only owned this boat for 3 years.
Maybe I'll just keep running the old one for while.

 

[stang32]

no, you can get the regular gates belt K061045

 

[achris]

Take your old belt to your local friendly car parts shop and get a Gates belt the same. 1/3 the price, same belt.

 

[stang32]

from the gates belt website

https://www.wanderlodgeownersgroup.com/downloads/GATES%20Belt%20Size%20Listings.pdf

Micro-V® Belts Listed by Number
K061037 ............................... 104 1/4 (2649) 40° 13/16 (20)
K061045 ............................... 105 (2666) 40° 13/16 (20)
K061058 ............................... 106 3/8 (2701) 40° 13/16 (20)
K061066 ............................... 107 1/8 (2722) 40° 13/16 (20) K

 

[Fun Times]

The old belt is 57-863876-3. The new belt I ended up with that is just a bit small is an 18-15102. Can somebody please direct me to the correct belt for this engine?
Thanks,

57-863876-3 should had been Sierra number 18-15100 - Belt
18-15100 Serpentine Belt Replaces Mercury 57-863876 3
Additional Details:

• Length: 106.25"
• Width: 13/16"

Model	CID / Cylinders	Year Range	Serial No. Range	Type of belt	Alternator / Water Pump Belt	Belt Length	Power Steering Belt	Belt Length	Sea Water Pump Belt	Belt Length

350 Mag BRAVO (RWC w / P / S)

350 / V-8

2002 - 2008

0M600000 & up

Serpentine

57-865615Q03 #'s 18 21 23

2704 mm

#'s
18 For engines with power steering
19 For engines without power steering
20 For engines with closed cooling
21 For engines with standard cooling
22 Replacement kit includes 5-3/4 in.(146 mm) pulley & longer serpentine belt
23 For engines with high mounted alternator

 

[achris]

57-863876-3 should had been Sierra number 18-15100 - Belt
18-15100 Serpentine Belt Replaces Mercury 57-863876 3
Additional Details:

• Length: 106.25"
• Width: 13/16"

That's a Gates 6PK2705.. About $30 on ebay. $90 from Merc.

 

[KD4UPL]

Thanks for all the help folks. I ended up getting one from Auto Zone for just over $20. Way better than the $75 or more they want for the "correct" Merc belt.