John Deere — Pressure Test Cooling System and Radiator Cap
Testing & diagnosis
From a John Deere operator's manual covering: 4039, 4045, 6059, 6068, RG4697. Check it applies to your exact model before use.
Applies to: John Deere 4039, John Deere 4045, John Deere 6059, John Deere 6068
Before you start
- Do not apply excessive pressure to cooling system; doing so may damage radiator and hoses
Procedure
- Remove radiator cap and attach to an approved tester.
- Pressurize cap to 50 kPa (0.5 bar) (7 psi). Gauge should hold pressure for 10 seconds within the normal range if cap is acceptable.
- If gauge does not hold pressure, replace radiator cap.
- Remove the cap from gauge, turn it 180 degrees, and retest cap.
- For cooling system test: allow engine to cool, then carefully remove radiator cap.
- Fill radiator with coolant to the normal operating level.
- Connect gauge and adapter to radiator filler neck. Pressurize cooling system to 50 kPa (0.5 bar) (7 psi).
- With pressure applied, check all cooling system hose connections, radiator, and overall engine for leaks.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Radiator cap test pressure: 50 kPa (0.5 bar) (7 psi), hold for 10 seconds
- Cooling system test pressure: 50 kPa (0.5 bar) (7 psi)
Full service-parts list: John Deere 4039 →, John Deere 4045 →, John Deere 6068 →
Source: John Deere operator'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.