sorry, had head up *** syndrome. the heat issue still applies. check releif pressures and if there is heavy usage of any attachment you should look into a flow divider. toyota's hydraulic system far exceeds the gpm tolerance of most attachments and what is not used goes through the releif valve and HOT happens. check the temp of the oil in the tank. i have seen oil temps over 200 degrees and oil does not cool as readily as water does. if heat is the issue adding a second cooler / replacing the cooler with external one usually lowers air flow and leads to more problems with related systems. unless you a can find a cooler that fits somewhere other than the radiator area you may not gain much.