HOW TO: 4WD Transmission Service

Regular fluid and filter changes are vital in keeping your 4WD’s automatic transmission in tip-top shape. Maintenance schedules differ between vehicles, but automatic transmission fluid and filters generally need to be replaced around 190,000km under normal usage or at smaller intervals if you do a lot of heavy-load driving, such as towing. However, if you’re starting to feel like your transmission isn’t performing how it should be, a transmission service should be your first course of action. Gremlins such as transmission slippage, strange noises, or poor shift feel are all signs that your transmission might be overdue for a service.

In this article, we look at servicing this Mitsubishi transmission using a Ryco Auto Transmission Filter Kit. To complete the job, you’ll need some fresh automatic transmission fluid and a transmission filter kit. 

This particular transmission uses a Ryco RTK290 Transmission Filter Kit which includes the transmission filter, new washers, a new o-ring, and a fresh transmission pan gasket. Visit the Ryco website to find the correct Transmission Filter Kit for your vehicle.

Ryco Transmission Filters work by removing contaminants to ensure that clean transmission fluid flows throughout the system at all times, which in turn maintains transmission life and overall performance.

The following procedure is a base guide for automatic transmission servicing. To begin, you’ll need to lift the vehicle on the hoist and position your drain pan. Transmission fluid drains better when warm, so idle the vehicle for a few minutes before lifting the car, making sure to not let the fluid get too hot.

Next, undo the drain plug on the transmission pan and allow the fluid to drain. Once drained, undo the transmission pan bolts and drop the transmission pan, making sure to catch the remaining fluid with your drain pan.

Once you have the transmission pan off the car, clean the pan mounting surface and transmission housing.

From here, it’s a good time to inspect the pan for any metal shavings or any other signs of internal damage.

Next, we can look at replacing the filter itself. To do this, undo the mounting bolts and remove the old filter and o-ring.

The old filter will have some fluid in it, so have your drain pan ready. From there, install the new Ryco transmission filter in reverse order with the new o-ring. When fitting up the new filter, take care to make sure everything seats up as it should.

With the fresh filter installed, it’s time to start putting everything back together. Take the new transmission pan gasket from your kit and fit to the transmission pan.

Then, refit the pan to the transmission pan with the supplied washers. From there, thread all of the transmission pan bolts finger tight, then torque to spec in a spiral pattern, starting from the centre of the pan.

With everything back together, the next step is to fill the transmission with fresh fluid. Look at the amount of oil that’s been drained, and refill the transmission with the same amount of fresh fluid plus a bit extra.

Then, refit the fill plug, start the vehicle, and take it through the gears two or three times to cycle the oil through and get it up to temp before draining to the correct level. To get the correct level on this transmission, there is a secondary plug that is removed to drain the excess fluid.