John Deere — Manual Belt Tensioner Adjustment Using Belt Tension Tool (Alternate Method For Engines Without Auxiliary Drive)
Adjustments · Fan/alternator belt
From a John Deere owner's manual covering: 4045TF120, 6068HF158, 6068TF120, 6068TF250. Check it applies to your exact model before use.
Applies to: John Deere 4045TF120, John Deere 6068TF120, John Deere 6068TF250
Procedure
- Loosen upper and lower alternator bracket cap screws. Keep lower cap screw snug enough to prevent excessive play.
- Insert JDG1520 Belt Tension Tool behind belt and over alternator mounting screw.
- Place torque wrench on belt tensioning tool at 90° to tool. Pivot alternator until desired torque is achieved.
- While holding tension with torque wrench, scribe a reference mark on alternator in line with notch on upper alternator bracket.
- Continue to hold tension and tighten upper alternator bracket cap screw.
- Check position of reference mark to see if alternator moved while tightening.
- Remove belt tension tool and tighten lower alternator bracket cap screw.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- New Belt—Tension 535—715 N (120—160 lb-force)
- Used Belt—Tension 400—580 N (90—130 lb-force)
Full service-parts list: John Deere 6068TF250 →
Source: John Deere owner's 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.