David Brown 990 Selectamatic service schedule

1. Stop the engine and take the key out. Keep naked flames away.
2. Remove the water trap and sediment bowl, empty them and clean them out.
3. Refit the bowl, then bleed at the inlet to the first fuel filter to get rid of all the air.
4. If a lot of water or dirt has got into the tank, drain the tank from the plug underneath.

Tools: Spanner, Container, Rags

1. Stop the engine and take the key out.
2. Take off the oil bowl, tip out the old oil and dirt, and clean the bowl.
3. Clean the wire mesh element in paraffin or diesel if it is dirty, and let it drain.
4. Refill the bowl to the level mark with engine oil. Too much oil can be drawn into the engine.
5. Refit the bowl and check all hose clips are tight so no unfiltered air gets in.

Tools: Drain tray, Paraffin or parts cleaner, Rags

1. Lower implements, stop the engine, take the key out and chock the wheels.
2. Wipe each nipple clean, then grease: rear hubs (2 shots only), clutch cross shaft (2 points), PTO clutch lever, sensing unit and its cable, handbrake cables (1 point each), lift ramshaft (3 points), lift rods (2 points), levelling lever (3 points) and top link.
3. Grease the front hubs until grease shows at the inside of the hub, and wipe off the surplus.
4. Oil the controls and pivots with engine oil (leave them dry in very dusty work).
5. Check the gearbox sight glass is at least half full, and the power steering oil with the wheels straight.
6. Top up the radiator to within 25 mm of the neck, only when cold. Release the cap slowly as the system is under pressure.
7. Top up the battery with distilled water, check tyre pressures and check all wheel nuts are tight.

Tools: Grease gun, Oil can, Rags, Tyre gauge

1. Park on level ground, lower implements, stop the engine, take the key out and chock the front wheels.
2. Clutch (not 996): the movement at the end of the master cylinder push rod should be at least 5 mm. To set it, unlock the nut and turn the screw adjuster anti-clockwise for more free play, recheck, then lock the nut.
3. Brakes: raise the rear wheels clear and support on axle stands; never work under a tractor held only by a jack.
4. Release the locknut and tighten the adjusting bolt until the brake starts to bind, then unscrew until it is just clear and lock the nut. Do the other side the same.
5. Lower the tractor and test both brakes together at low speed; it should stop in a straight line.

Tools: Spanners, Jack and axle stands, Wheel chocks, Rule

1. Run the engine to warm the oil, then park on level ground, lower implements, stop the engine, take the key out and chock the wheels.
2. Let it stand a few minutes. Hot oil burns, so wear gloves.
3. Remove the sump plug and drain the oil while it is still warm. Refit the plug.
4. Undo the bolt in the end of the filter and take off the cover. Throw away the old element.
5. Wash the cover in diesel with a small brush, not a cloth: fluff can foul the bypass valve seat.
6. Fit the new element, check the rubber sealing ring in the block, and tighten the bolt to 1.4 kg m (10 lb ft).
7. Fill the sump to the safe mark on the dipstick.
8. Turn the engine on the starter to fill the filter, start it, check the cover for leaks, stop and recheck the dipstick.

Tools: Drain tray (10 L), Spanner for sump plug, Spanner for the filter centre bolt, Small brush, Diesel for washing, Torque wrench, Gloves

1. Stop the engine, take the key out and chock the wheels. Keep naked flames away.
2. Clean the outside of the first filter.
3. Unscrew the centre bolt while holding the filter body with your other hand.
4. Throw away the old element and flush the base until clean.
5. Fit a new sealing washer under the bolt, and seat the new element on the rubber rings in the cover and base.
6. Do the same with the second filter.
7. Clean out the sediment bowl on the fuel lift pump.
8. Bleed: loosen the connection at the lift pump (and at the inlet to the first filter) and pump until fuel comes out with no air, then tighten.

Tools: Spanners, Container for fuel, Clean diesel for flushing, Rags

1. Park on level ground, lower the linkage and any implement fully to the ground, stop the engine, take the key out and chock the wheels.
2. Move the hydraulic lever to lower and work any spool valves to let out trapped pressure.
3. Let hot oil cool to warm before draining, and wear gloves.
4. Drain the oil from the drain plugs into a clean container (both plugs to empty the rear axle case).
5. Change the full-flow element and clean the nylon bypass filter and the magnetic plug.
6. Pour the clean oil back in, but throw away the last 3 litres with the sediment, and top up with new oil.
7. Run the engine at idle for 30 seconds with the hydraulic lever in lower so the system bleeds itself, then check the level.

Tools: Large clean drain tray (30 L), Spanners, Funnel, Gloves

1. Stop the engine, take the key out and chock the wheels. Work on a cold engine.
2. Remove the bonnet and rocker cover. The engine is easiest to turn by the fan belt with the injectors out.
3. Number the valves 1 to 8 from the front. Turn the engine until one valve is fully open, then adjust the valve whose number adds up to 9 with it (1 with 8, 2 with 7, 3 with 6, 4 with 5).
4. Slacken the locknut, turn the screw until a 0.25 mm feeler is a light drag between rocker and valve stem, hold the screw and tighten the locknut.
5. Work through all eight valves, then refit the cover and check for leaks.

Tools: Feeler gauges, Ring spanner and screwdriver, Spanners for rocker cover

1. Stop the engine, take the key out and chock the wheels. Keep naked flames away.
2. Clean around each injector and pipe union, remove the injectors and cap the open pipes.
3. Have them tested and set by a diesel specialist.
4. Refit with new washers, then bleed the fuel system before starting.

Tools: Spanners, Caps for open fuel pipes

1. Work the tractor so the oil is warm, then park level, lower all implements, stop the engine, take the key out and chock the wheels.
2. Work the hydraulic lever and any spools with the engine off to let out trapped pressure.
3. Wait a few minutes so the oil is warm, not scalding, then remove the main frame and rear axle drain plugs.
4. Change the hydraulic filter element and clean the bypass filter and magnetic plug.
5. Refit the plugs and fill with new oil to the mark.
6. Drain the belt pulley (where fitted) and refill to its level plug with the same oil.
7. Run the engine at idle for 30 seconds with the lever in lower, then recheck the level.

Tools: Large drain tray (30 L), Spanners, Pump or funnel, Gloves

1. Park level, lower implements, stop the engine, take the key out and chock the wheels.
2. With the oil warm, remove the drain plug on each final drive housing and let it drain. Wear gloves.
3. Refit the drain plugs and fill each unit to its level plug with new oil.

Tools: Drain tray, Spanners, Oil pump or squeeze bottle

1. Stop the engine, take the key out and chock the wheels.
2. Clean around the steering reservoir thoroughly before opening it.
3. Fit a new filter element as the handbook shows.
4. Top up with new oil, start the engine, turn lock to lock to drive out air, then recheck the level with the wheels straight.

Tools: Spanners, Lint-free rags, Drain tray

1. Only work on a cold engine. Take the radiator cap off slowly to let any pressure out.
2. Open the radiator drain tap and the cylinder block drain (two points), with the cap off so it all drains.
3. Flush through with clean water, then close the drains.
4. Refill with the antifreeze mix, run the engine to warm up, let it cool and top up to within 25 mm of the neck.

Tools: Drain tray, Hose, Antifreeze tester