Fan belt wear

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rob1miles

Well-Known Member

Posts

3,565

Location

Slough and Bath

• Nov 20, 2018

• #1

My Perkins seems to be quite hard on fan belts, its a single 1/2" belt and a 70A alternator. The alternator pulley doesn't get a lot of contact angle and with the low revving engine the belt needs quite a lot of tension or it slips. I think I'm getting 6000 miles out of a belt if I replace when its quite clearly worn. Anyone found any belts that last better?

 

tottot

Well-Known Member

Posts

8,082

Location

west wales coast

• Nov 20, 2018

• #2

You may need a belt with a different profile. You should be able to find an agri spares place in your area.Take your old belt along and see if they can fix you up. Many Perkins motors still at work in agriculture.

 

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rob1miles

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Posts

3,565

Location

Slough and Bath

• Nov 20, 2018

• #3

Thanks, you got me thinking about the profile. It does look like the engine pulley and alternator pulley form don't quite match, close but not exact. You may have set me in the right direction.

 

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Colthebrummie

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9,870

Location

Thatcham

• Nov 21, 2018

• #4

If your Pullys don't have the same profile, you probably need to change one or both.

Col

 

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rob1miles

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3,565

Location

Slough and Bath

• Nov 21, 2018

• #5

It looks like the crank and water pump pully are deeper than the alternator pulley and the belt rides high on the alternator. I'm going to see if I can get a matching pulley but in the meawhile I'm also going to try a cogged ((AVX) rather than A type belt.

 

Stretch

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Posts

1,600

Location

Holland

• Nov 21, 2018

• #6

(Make sure the pulleys are the same type as mentioned above)

Make sure the pulleys are aligned ridge to ridge - trough to trough. If the belt doesn't run true then it will slip / and or need silly tension. Rule of thumb for the tension:- Twist the longest length by a quarter turn - should be about all it wants to go with out the feeling it is a tight as a piano wire.

 

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rob1miles

Well-Known Member

Posts

3,565

Location

Slough and Bath

• Nov 21, 2018

• #7

Thanks, what kicked this off was finding that it was not chargeing when both the headlights and heater fan were on. Suspected alternator or poor connnection then checked fan belt and found it more worn than I expected and looser. Not really loose but clearly enought to slip once the alternator output was needed. I'm going to take a few carefull meaurements, we have a guy who overhauls alternators nearby and I think I'll drop by and see what he has in the way of alterntor pulleys, the the meanwhile an new AVX cogged belt is on its way via e-bay, I'm hoping this sits a bit lower in the pulleys.and at £4 inc postage I can afford to hope!