Symptoms
The temperature gauge climbs on long climbs or when towing, the truck boils at low speed, or the clutch fan roars without cooling much. GQs have a reputation for heat, and an overheated head is the expensive end of that story. On automatics, the transmission cooler is inside the radiator.
The fix, step by step
- Pressure-test the system and check the radiator for blocked cores.
- Replace the top and bottom hoses and the thermostat (TD42 trucks use a 76°C genuine unit).
- Inspect the water pump for weeping and the fan clutch for slip, and bleed the system properly.
- CarsGuide says most TD42 overheating is on modified trucks: aftermarket turbos add heat, front-mounted intercoolers and driving lights block airflow, and big tyres make the engine work harder.
- If the head has already been cooked, have it pressure-tested and checked for warp at a machine shop before refitting.
Tools & part numbers
- Cooling-system pressure tester
- drain pan
- hose pliers
- new clamps
- coolant (type per manual).
Where to buy the parts
Koyorad radiator, GQ/Maverick diesel 1988–1997 manualHD Automotive ↗Amazon ↗
Genuine TD42 76° thermostat 21200-58G04HD Automotive ↗Amazon ↗
Gates radiator hose set, GQ TD42HD Automotive ↗Amazon ↗
Asahi TD42 water pump, GQ/GUHD Automotive ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Nissan Patrol Y60 (GQ) parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.