Series 3 Fan belts snapping

WoodyO · Oct 24, 2023

Afternoon all,

I had some issues with the fan belt snapping on a drive yesterday, I carry a spare but about 20 miles afterwards that snapped too.

Correctly tensioned and a new belt, so concluded it must have been the pulleys that caused it.

Whipped them off today and there's a build up of rubber in the base of the pulley. I'm hoping this was the cause, not letting the belt sit properly in the pulley.

New pulleys ordered rather than cleaning up the old ones, along with a bunch more belts just in case.

kermit_rr · Oct 24, 2023

Is everything spinning ok?

lynall · Oct 24, 2023

Is it 3/8 or 1/2 inch belt? as it looks like the belt has been touching the bottom of the pulley groove.

Generally v belts will take a load of abuse and still work just fine.

tottot · Oct 24, 2023

Looks like you have been using an under size belt, as in width. Belt should not contact bottom of the pully wheel.

WoodyO · Oct 24, 2023

Everything turning okay, new alternator and water pump, no excess play in any bearings.

Dayco 10A1050C belt, so 10mm width.

I think it's been contacting the bottom of the groove only due to the build up of rubber.

lynall · Oct 24, 2023

WoodyO said:
Everything turning okay, new alternator and water pump, no excess play in any bearings.

Dayco 10A1050C belt, so 10mm width.

I think it's been contacting the bottom of the groove only due to the build up of rubber.

I reckon you should have a 13mm belt, 10mm is only just okay to just drive an alternator on its own, but to drive alternator and water pump you need the wider belt.
Only reason it is touching the bottom of the pulley is the belt you had fitted is to narrow.

WoodyO · Oct 24, 2023

Appreciate the feedback, but the 10mm is the standard belt for the 2.25, OEM number returns the same size belt from different suppliers.

dag019 · Oct 25, 2023

new pulley may help, But you could also wire wheel all the existing pulleys to give a nice smooth clean groove. I found that recently with and engine I fitted that had been standing for a while. chewed through several belts before fully cleaning up all of the pulleys and no problems since.

lynall · Oct 25, 2023

WoodyO said:
Appreciate the feedback, but the 10mm is the standard belt for the 2.25, OEM number returns the same size belt from different suppliers.

With the 10mm belt, is the top of the belt flush with the top of the pulleys, or below the top?
New belt toothed or plain?

WoodyO · Oct 25, 2023

All sorted, thanks again for the input.

Fitted the new pulleys today and did a the 230 miles back home without any issue. Although I now have 3 spare belts just incase.

The toothed 10mm belt (Dayco 10A1050C) sits flush with the top of the pulley, no sign of bottoming out at all.

I'm confident the pitted surface of the old pulleys, coupled with a build up of rubber in the bottom of the groove was to blame.

Would have cleaned up the old pulleys had the new ones not been available next day, but they'll be kept as spares just in case.

dag019 · Oct 25, 2023

WoodyO said:
All sorted, thanks again for the input.

Fitted the new pulleys today and did a the 230 miles back home without any issue. Although I now have 3 spare belts just incase.

The toothed 10mm belt (Dayco 10A1050C) sits flush with the top of the pulley, no sign of bottoming out at at.

I'm confident the pitted surface of the old pulleys, coupled with a build up of rubber in the bottom of the groove was to blame.

Would have cleaned up the old pulleys had the new ones not been available next day, but they'll be kept as spares just in case.

You were lucky they were available next day when I did mine I ordered them and cleaned up the old ones as a stop gap which then sorted and solved the problem so the new ones are now sat on the shelf as spares!

WoodyO · Oct 26, 2023

There's a great little independent called A L Services in Poole, Dorset if anyone is that way. Good service and has daily deliveries.

Series 3 Fan belts snapping

WoodyO

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kermit_rr

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lynall

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tottot

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WoodyO

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lynall

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WoodyO

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dag019

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lynall

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WoodyO

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dag019

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WoodyO

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