John Deere — Manual Belt Tensioner Adjustment
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
Before you start
- Do not pry against alternator rear frame.
Procedure
- Install JDG1341 Belt Tension Gauge on belt, halfway between pulleys.
- Loosen cap screws.
- Slide alternator or tensioner bracket in slot by hand to remove all excess slack in belt.
- Stretch belt by prying outward on alternator front frame or tensioner bracket until specified tension is achieved.
- Tighten cap screws.
- Run engine for ten minutes and immediately re-check belt tension per used belt specification.
- Reset belt tension as necessary.
Tools required
- JDG1341 Belt Tension Gauge Amazon
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)
- Old Magneton Alternator New Belt (Option Code 3101) Tension 470—650 N (105—145 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.