John Deere — Pressure Testing Cooling System
Testing & diagnosis
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
- Explosive release of fluids from pressurized cooling system can cause serious burns. Only remove filler cap when cool enough to touch with bare hands.
Procedure
- Test radiator cap: remove radiator cap and attach to D05104ST Tester.
- Pressurize cap to specification. Gauge should hold pressure for 10 seconds within normal range.
- If gauge does not hold pressure, replace radiator cap.
- Remove the cap from gauge, turn it 180°, and retest cap.
- Test cooling system: allow engine to cool, remove radiator cap, fill radiator with coolant to normal operating level.
- Connect gauge and adapter to radiator filler neck and pressurize cooling system to radiator cap specification.
- With pressure applied, check all cooling system hose connections, radiator, and overall engine for leaks.
- If leakage is detected, correct and pressure test again.
Tools required
- D05104ST Tester Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Radiator Cap Holding Pressure (Not Opening For 10 Seconds) 70 kPa (0.7 bar) (10 psi) minimum
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.