When to change serpentine belt?

[DEcosse]

So that's OEM belt @Big Block Power ?
I'm not necessarily against OEM, other than the price ($90 on Amazon vs $40 for the Gates Fleetrunner)
- but if there's more robust belts for less $$$ why not?

[Titaniumboy]

It is kind of rare in our boating world, but the car enthusiasts face this issue all the time of needing custom sized belts when they move things around. One trick they use is to route a string around the serpentine belt pathway and get a length measurement. They then take that measurement to the auto parts store and pick up three different belts; one sized from the string, and then the next size smaller and larger.

It is also possible that places like NAPA or O’Reillys might be able to do a cross reference of the VP belt.

[Titaniumboy]

It looks like I need to replace mine on my 8.1 OSi which is same OEM part number as the 8.1 GXi
e.g. originally 3817290 now 21132390

It looks like your belt covers a LOT of VP engines

https://www.poseidonmarine.eu/products/ ... 90-3817290

• Serpentine Belt for Volvo Penta
  
  Reference OEM part number: 21132390, 3817290, 3861034, 3889126
  
  Suitable for the following Volvo Penta engines:
  
  4.3GL-J, GL-JF, GXI-J,
  GXI-JF, OSI-J, OSI-JF
  
  5.0GL-J, GL-JF, GXI-J,
  GXI-JF, OSI-J, OSI-JF
  
  5.7GI300-J, GI300-JF
  5.7OSI-J, OSI-JF
  5.7GXI-J, GXI-JF
  5.7OSXI-J, OSXI-JF
  
  8.1GI-H, GI-HF
  8.1GXI-G, GXI-GF
  8.1OSI-D, OSI-DF

[Titaniumboy]

These are the dimensions I found for the parts numbers
Dayco 5060915 is 2325mm or 91.54"
K060910 is 2329mm or 91-11/16

So you can see in fact the 5060915 is 4mm (little over 1/8") difference (smaller) from the K060910 and he did say it was noticeably slightly smaller than the OEM so it looks like indeed @smokymance K060910 reference is the one to get!

I think you may be comparing slightly different specs for the Dayco 5060915 as compared to the Gates K060910. You listed the “effective length” for the Dayco, but used the “outside circumference” for the Gates. The “effective length” for the Gates K060910 is 91.11” or 2314mm, and is 14 mm shorter than the Dayco.

The Gates Fleetrunner K060910HD is the same size as the Gates K060910.

Dayco 5060915 https://www.daycoaftermarket.com/en/cat ... rt=5060915

Gates K060910 https://www.gates.com/us/en/automotive/ ... 08496.html

Gates Fleetrunner K060910HD https://www.gates.com/us/en/automotive/ ... 00496.html


Here are some technical documents from Gates. The first one describes what the terms Effective Length, Outside Circumference, PK number, etc all mean. One section says “Although a scientifc calculation is the only way to determine the actual outside circumference, on average, adding 14 mm to the efective length results in an outside circumference.”

Gates Technical Service Bulletin (TSB_0050).pdf

Gates Belt ID Chart.pdf

Here is a short thread on iboats where someone used a 91” (or 2313mm) belt in place of the Volvo Penta 21132390 belt, albeit for a VP 5.7 GI-J. That NAPA branded belt is almost certainly made by Gates.

https://forums.iboats.com/threads/5-7gi ... lt.745009/

E0C36128-7714-45A8-BD7E-57A04A08FBAB.jpeg

[DEcosse]

A TON of good info there @Titaniumboy
So it looks like another 'vote' for the 060910 (or KO60910)

Napa is strange around here - different prices at different stores!
That Part number NBH 25060910 is $32.99 at one store and $54 & $56 at others!!

At O'Reilly - Gates is $37, Gates FleetRunner is $57; Master Pro is $22.

FleetRunner marketing infor - https://assets.gates.com/content/dam/pr ... -belts.pdf. It's $40 on Amazon

There is also this one - https://www.gates.com/us/en/search.p.85 ... 96910.html
Those have Aramid cord vs Polyester
Very pricy relatively - typically in the $125 range - but found this https://www.ebay.com/itm/115408464750 - quite the deal at $66 IF it's genuine Gates RPM
(edit - I took a look at that EBay seller's feedback ratings - absolutely horrible!!!)

Continental anyone?
Continental bought Goodyear Gatorback Belt business a few years ago.

[Titaniumboy]

Thanks!

Looks like you’ve been shopping. The price differentials you are seeing is kind of crazy. Not as crazy as an eBay feedback of 86.8% - normally a bad feedback is anything below 98.5% or 98%. I’ve never seen a feedback score that low.

So it looks like another 'vote' for the 060910 (or KO60910)

Maybe, maybe not. Didn’t you say that somebody found the K060910 noticeably shorter than the OEM one even though it still worked? Gates also has a K060913, a K060915, and a K060919 to choose from. Basically you can dial in belt sizes in small increments.

40CF6F21-B7B5-4CF2-8DF1-129227F52E65.png

If you REALLY want to get into the weeds (and I know you do), look into how to measure wear on these “new” EPDM belts.

https://www.gates.com/us/en/industries/ ... -wear.html


I bought a Dayco aWEARnesss Gauge last year during my deep dive on serpentine belts. They are relatively inexpensive and can be had for under $7 on eBay. There are other belt wear gauges out there, but I liked this one the best.

https://www.ebay.com/sch/i.html?_from=R ... e&_sacat=0

[DEcosse]

... Didn’t you say that somebody found the K060910 noticeably shorter than the OEM one even though it still worked? ...

I believe that was the guy with the Dayco 5060915 although that should be longer than the *910

[Titaniumboy]

I found it almost impossible to find length info on the Volvo Penta belts. I had much better luck finding clues to the length of Mercruiser belts.

And if you really really want to do an even deeper dive, ponder the question of belt tightness. What is the correct belt tension? How do you KNOW? (Hint: there are tools)

[Big Block Power]

So that's OEM belt @Big Block Power ?
I'm not necessarily against OEM, other than the price ($90 on Amazon vs $40 for the Gates Fleetrunner)
- but if there's more robust belts for less $$$ why not?

Good stuff here. I like leaders.

[DEcosse]

Nice!

[Big Block Power]

First belt lasted 17 years so why not stick to what works.

[DEcosse]

Meanwhile I had a new belt for my Alternator replacement on my Lexus V8 over the weekend and got a Continental (next day delivery from Amazon) - I thought it looked great quality so got the same for the VP

... I like leaders ...

I followed your lead (no pun intended!) and looked on the LeadersRPM site - the tensioner* was $126 plus shipping
On EBay however - same part sold by Leaders there $83 and free shipping - go figure
I guess their EBay business has a different model.

*see my other 'clicking' thread for the story on that

[Big Block Power]

Meanwhile I had a new belt for my Alternator replacement on my Lexus V8 over the weekend and got a Continental (next day delivery from Amazon) - I thought it looked great quality so got the same for the VP

... I like leaders ...

I followed your lead (no pun intended!) and looked on the LeadersRPM site - the tensioner* was $126 plus shipping
On EBay however - same part sold by Leaders there $83 and free shipping - go figure
I guess their EBay business has a different model.

*see my other 'clicking' thread for the story on that

Yes I watch both of them and get more off of ebay also.