John Deere — Check Fan/Alternator Belt Tension
Maintenance · Cooling system
From a John Deere service manual — check it applies to your exact model before use.
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Before you start
- Do not pry against the alternator rear frame
- Do not tighten or loosen belts while they are hot
Procedure
- Check belt tension using JDG529 Tension Gauge or a tension tester and straightedge
- On engine with dual belts check tension of front belt only
- If adjustment is necessary loosen alternator nuts and pull alternator frame outward until belt correctly tensioned
- Tighten alternator bracket nuts firmly
- Run engine for 10 minutes then recheck belt tension
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Single belt (new) 578—622 N (130—140 lb-force)
- Single belt (used) 378—423 N (85—94 lb-force)
- Dual belt (new) 423—467 N (95—104 lb-force)
- Dual belt (used) 378—423 N (85—94 lb-force)
- 19 mm (0.75 in.) deflection with 90 N (20 lb-force) halfway between pulleys
Source: John Deere service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.