Serpentine belt question

Liberty44140Liberty44140 Member Posts: 4,381 ✭✭✭✭✭
edited April 2017 in Engine Discussions
should gates belts lengths be exactly consistent?

this weekend I did both water pump impellers so I put brand new gates belts on at the same time. Bought both gates belts at the same time. oem belts were on there, the right ones. The old belts slipped right off when I lowered the tension pulley on each side. I think the tensioners were  maxed or close to max but I don't know. Anyway the port new gates belt went on like the old, went on fine and I've got the tensioner at or close to max to get the right tension. I can twist the belt at or just past a quarter turn at the longest run and there is 1/2" thumb deflection. The starboard new gates belt however was hard to get on with the tensioner fully lowered, had to really pull to get it on. I did have to use the tensioner to get the same tension as the port motor but it's certainly not maxed out. So that leaves my question, is it possible that one gates belt was slightly shorter than the other? Bought the same time but one was made in the us and the other in mx so i would think that it's possible that it's 1mm shorter even though it's same upc and same gates part number. Both sides tensions are the same and fine after sitting overnight. 
07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)

Post edited by Liberty44140 on

Comments

  • Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    The belts are made on a drum, so yes you can get length varyation from belt to belt unless you purposely buy matched sets.  It takes very little difference in belt length to effect the adjustment 'lots'.  

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
  • Mercury2005Mercury2005 Member Posts: 141 ✭✭
    how are aftermarket belt part numbers matched to the factory Mercury part numbers?
  • Liberty44140Liberty44140 Member Posts: 4,381 ✭✭✭✭✭
    @Mercury2005 I went by length. The factory belt is 2667mm so I bought a 2666mm belt (this could have explained the new going on a little tight on the stbd if it were not for the port fitting the same as the old merc). If you google your oem belt you will likely find the Gates or Napa conversion in other threads out there. Most belts have an exact match, mine happened to be within 1 mm. 

    @Black_Diamond thanks. I work for a manufacturing company so it made sence to me that there would be a +/- tolerance especially since these came from different countries but wanted to make sure there was nothing to worry about. I spent some time looking in to this last night and there are indeed tolerances on belts. I couldn't find the exact tolerance for these belts but it looks like it could be 5mm or almost 1/4". 

    Next time I buy belts I will be much more anal to make sure they come from the same lot, same country, etc... I ordered these from Walmart.com :)
    07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)

  • Mercury2005Mercury2005 Member Posts: 141 ✭✭
    @Liberty44140
    How would you determine belts come from the same lot, etc?
  • Liberty44140Liberty44140 Member Posts: 4,381 ✭✭✭✭✭
    They have all kinds of numbers on the belts themselves. I'd just try to buy in the store, not online, and match up as much as possible. 
    07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)

  • Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Well as chance happens, I'll be at Gates corporate today in Denver.  I can get some info on the tolerance.

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
  • Liberty44140Liberty44140 Member Posts: 4,381 ✭✭✭✭✭
    Nice! I used their K061045 micro-v
    07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)

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