Quick Summery
The 400-hour service is a comprehensive maintenance interval for the Kubota MX5800. This service involves replacing the engine oil (7.4 qt), roughly 12 gallons of hydraulic fluid, and multiple filtration components. Key focus areas include the dual engine oil drain plugs, the hydrostatic transmission (HST) magnet, and the fuel sediment bowl. Using genuine parts from Messick's ensures your machine maintains its performance and longevity.
Performing your own 400-hour service is a great way to get to know your Kubota MX5800. Pro Tip: Before you begin, ensure your brush guard is moved all the way forward. The hood on the MX series swings up high, and you can easily scratch or dent it against the guard if it isn't cleared first.
Tools Required
According to our service walkthrough, you will need the following tools gathered before you begin:
- 24 mm socket or wrench: For the main transmission drain plug.
- 19 mm socket (6-point preferred): For the axle low-point bolts.
- 14 mm socket: For engine oil drain plugs.
- Oil Filter Wrench: One capable of fitting 3-1/2" to 3-7/8" filters.
- Large Drain Pan: Must hold at least 11.4 to 12 gallons of fluid.
- Safety Glasses: Essential when using brake clean on the fuel screen.
1. Transmission and Hydraulic System
This is the largest part of the service, as the transmission holds approximately 11.4 gallons of fluid. Start by draining the main transmission plug, followed by the two bolts on the bottom of the axle low points. Be careful not to lose the washers; the main plug uses a specific washer with a rubber O-ring—reinstall it "paint side down" as it came from the factory.
When replacing the Hydraulic Oil Filter (HHTA0-37710), remember that the HST side typically features a magnet. Clean any metal shavings off the magnet and move it to the new filter. For refilling, a modified milk jug can act as a perfect funnel for the awkwardly placed red fill port. We recommend using Kubota Super UDT2 Fluid (70000-40205) for best results.
2. Engine Oil and Filter
The Kubota MX5800 features a split oil pan. You must remove both drain plugs to get a complete drain. Once empty, swap the old filter for a new Engine Oil Filter (HH164-32430). Pre-lube the O-ring with clean oil—never use old oil for this. The engine calls for 7.4 quarts; fill with 7 quarts first, run the engine, then check the dipstick to top off to the 3/4 mark.
3. Fuel System and Air Filter
First, service the fuel sediment bowl. Flip the fuel lever to "Off," remove the housing, and blast the screen with brake clean to remove gunk and sediment. After reinstalling the screen, replace the Spin-on Fuel Filter (HH1J1-43172). Cycle the key for 15 seconds to let the fuel pump prime the system before starting.
Finally, open the three clips on the air housing to replace the Outer Air Filter (R1401-42270). Wipe the housing out with a rag first, and ensure the dust boot is pointing toward the bottom so debris can collect and exit correctly.
Frequently Asked Questions
How much hydraulic fluid does a Kubota MX5800 hold?
The system holds approximately 11.4 to 12 gallons. Because of the high volume, ensure you have a large enough drain cart or multiple 5-gallon buckets ready before pulling the main plug.
Why are there three drain points for the transmission?
The main plug drains the bulk of the fluid, but the two axle bolts are at the absolute low points of the machine. Draining these ensures you remove all contaminants and water that may have settled at the bottom.
Where should the engine oil level sit on the dipstick?
After filling with 7.4 quarts and running the engine briefly, the oil level should sit between the two hash marks. Aiming for the 3/4 mark is ideal for most operating conditions.
