The average ute takes a pretty heavy beating in the course of its duties, especially if it is frequently used off-road or for carrying heavy loads, and the various components that enable it to run smoothly are not immune to this punishment. A ute's gearbox and transmission system, while robust and constructed with ruggedness in mind, is no exception, and a variety of issues can affect the function of a ute gearbox over the course of its working life.
One of the most common problems that affects ute gearboxes is chronic overheating, and getting to the root cause of these persistent heat issues can be a challenging. A wide variety of malfunctions can cause ute gearboxes to overheat, and having the gearbox inspected and repaired by a professional gearbox repair tech is generally the fastest and most reliable option. However, you can attempt to rule out some of the more common causes of gearbox overheating yourself by checking for the following problems:
Gearbox fluid problems
Automatic and manual gearboxes alike are heavily reliant on the fluid surrounding the gears themselves. This fluid services two functions; its lubricating properties educe friction and wear of the gears, while its heat conducting properties allow it to draw excessive heat away from moving parts. As you can imagine, problems with this fluid can rapidly lead to overheating issues.
Your first port of call should be to check the fluid levels inside your gearbox, but sufficient fluid does not entirely rule out gearbox fluid problems. Ascertain the original colour of your chosen gearbox fluid (most brands are dyed red, but green and blue variants are also sold) and compare it to the colour of the fluid in your gearbox.
If the fluid in the gearbox is darker, it may have aged and become less effective, necessitating fluid replacement. Significantly paler fluid may have been contaminated with water, and will also have to be replaced. Water-tainted fluid is generally caused by a leak somewhere in the gearbox housing or fluid lines, so if this problem presents itself you should conduct a thorough search for the leak that allowed the water to enter your fluid supply.
Gearbox pump failure
All automatic gearboxes, and some manual models, are fitted with a pump to pressurise the fluid inside. This pump ensures that the gears receive a ready supply of cooling fluid, and is also vital for proper functioning of the clutch, so a malfunctioning pump can cause both overheating problems and noticeably slugging and laboured shifting between gears.
If this combination of problems affects your gearbox, inspect the pump for malfunctions; if you are lucky, it may simple be clogged with sediment, and removing and cleaning the pump filters can solve the issue. If the problem is more mechanical in nature (such as a burnt-out motor), professional repairs are in order.
Your gearbox's solenoid controls the valves that allow fluid to flow from the reservoir to the gear housing, and is frequently one the first components of an older gearbox to fail. Without a functioning solenoid, these valves remain closed and your gearbox is deprived of fluid, causing rapid overheating issues. Solenoids are generally small and inexpensive, and replacing them is usually more economical than repairing them.