While staying at Overlander Oasis in Mexico (https://www.overlanderoasis.com) I took the opportunity to work with Calvin to improve the engine and gearbox cooling by installing some baffles and a heat shield.  Having installed a snorkel, the original space in the grill for the air intake was allowing air to escape into the engine compartment.  We therefore made a simple baffle to cover this space and direct more air through the intercooler.

Next we installed a couple of baffles, one on each side between the radiator and the bumper.  These will prevent the air coming through the front grill from ‘spilling’ around the sides of the radiator.  The left baffle also made a good location to attach a new air duct running to the fuel cooler, see Fuel Cooler

The final item was fitting a heat shield between the exhaust system and the main gearbox. I had previously found that during long, slow, steep, hill climbs the main gearbox temperature increased to very high temperatures, over 120°C (I had been stopping on climbs to allow it to cool down once it reached 110°C).  The new heat shield stops the heat from the turbos and exhaust from heating the side of the gearbox.

Having test driven with these modifications for 850 km (driving from 1500m amsl to 3000m amsl on slow steep roads, then down to sea level, then back up to 2500 m amsl on fast steep dual carriageway, all with the vehicle loaded between 5800 kg and 5900 kg, with outside temperatures of 25°C to 35°C) the ECU data is showing it has helped significantly.  The gearbox cruising temperature has now reduced from 85°C to 70°C, and the modification has had a similar effect for the transfer gearbox too, which is a bonus.  On steep, slow, climbs the main gearbox still gets hot, but regardless how hard the vehicle is pushed, the temperature no longer rises above 105°C. The gearbox temperature also reduced far more quickly than before the modification.

The baffles have also resulted in a noticeable increase in power, although I don’t have data to quantify this. My guess is that the extra cooling through the intercooler must be making a difference.

Another benefit I have noticed is that the cooling-fan cycles a lot less frequently and the highest temperatures recorded by the ECU have also reduced.

Overall, I am very happy with the modifications and the effects they have had to the truck’s cooling systems.

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