MGB Maintenance Schedule

[Ed. Note- Not sure how to perform the procedures listed below? Read the Basic Servicing Articles in the MG Experience Tech Library or purchase some of the how-to books in the MG Experience Book Store such as the Haynes manual or Lindsay Porter DIY Guide.]

The maintenance instructions listed below are basically those recommended by the manufacturer. They are supplemented by additional maintenance tasks which, through practical experience, the author recommends should be carried out at the intervals suggested.

The additional tasks are indicated by an asterisk, and are primarily of a preventative nature in that they will assist in eliminating the unexpected failure of a component due to fair wear and tear.

The levels of the engine oil, radiator cooling water, windscreen washer water, and the battery electrolyte, also the tyre pressures, should be checked weekly, or more frequently if experience dictates this necessary. If not checked a home it is advantageous to regularly use the same garage for this work, as gauges vary. Tyres should be checked cold.

Note the engine oil change for the engine is put at 3,000 miles. The manufacturer recommends changing the oil at 6,000 miles but changing the engine oil more frequently will extend the life of the engine.

3,000 Miles Service
EVERY 3,000 MILES (or every 3 months if 3,000 miles not exceeded).

1. Unscrew the tops of the carburettor dashpots, lift out the damper assembly 'A' in Fig.3 and top up with SAE 20W50 engine oil to within 1/2 inch of the top of the pots (arrowed). Oil the carburettor controls.
2. Fill a grease gun with LM grease or a similar recommended multi-purpose grease and thoroughly lubricate the following through the appropriate grease nipple, which should first be wiped clean. Give 3-4 strokes of grease gun to:-
   1. The front suspension upper and lower swivel pin bush and the lower swivel pin (2 or 3 nipples on each side of the car). See Fig.4. Total no. of nipples to grease - 6.
   2. The universal joints on the front and rear of the propeller shaft (early cars only) and the sliding joint. Se Fig.5. Total no. of nipples to grease - 3.
   3. The handbrake cable. See Fig.6. Total no. of nipples to grease - 1.
3. Check the level of the hydraulic brake fluid in the clutch and brake master cylinder resevoir and top up if the level has fallen to 1/4 inch or more below the bottom of the filler neck, with Castrol LMA or DOT4 brake fluid. See 'A' and 'B' in Fig.7.
4. Check the steering column clamp bolts for tightness.
5. Adjust the rear brakes, and on the front disc brakes inspect the friction pads for wear. Check the hoses and pipes for loose joints, or leaks or wear. Check the hoses and pipes for loose joints, or leaks or wear caused by the suspension or tyres rubbing against the flexible piping.
6. Wash the bodywork and chromium fittings with clean water and a small amount of dishwashing detergent and clean out the interior. Apply a coat of wax, it will not only beautify but gaurd against rust formation. *
7. Check that all the lights are functioning correctly and replace blown bulbs as necessary. *
8. Lubricate with SAE 20W50 oil the door hinges, bonnet lock operating mechanism, and the safety catch.
9. Lubricate the boot catch and hinges with SAE 20W50 oil
10. Check the battery cell specific gravity readings, and clean the terminals.
11. Lubricate the dynamo (generator) rear bearing.
12. Examine the fan belt and adjust as necessary for the correct tightness.

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6,000 Miles Service
EVERY 6,000 MILES (or every 6 months if 6,000 miles not exceeded).

1. Run the engine until it has reached its normal working temperature. Then drain the oil from the sump by undoing the drain plug (arrowed in Fig.9).
   Undo the filter and renew the element (or replace the spin-on filter). Refill the sump with 7 1/2 pints of SAE 20W50.
2. Perform all the maintenance tasks listed for the 3,000 mile service.
3. Check the condition of the heater and cooling system hoses and replace as necessary. *
4. Lubricate with engine oil the pivot point of the brake and clutch pedal shafts. *
5. Check the fuel lines and the union joints for leaks and replace defective parts as necessary. *
6. Remove and clean the filters in the carburetters and fuel pump where these are fitted. *
7. Check and adjust the valve rocker clearances.
8. Remove the distributor cap, pull off the rotor arm and apply three drops of engine oil to the head of the large screw in the centre of the distributor. See 'B' in Fig.11.
9. Allow three drops of oil past the cam to the automatic timing mechanism. See 'A' in Fig.11.
10. Lubricate the four-sided cam by smearing a faint trace of grease over it. See 'C' in Fig.12.
11. Apply a tiny spot of oil to the moving contact breaker pivot pin. See 'D' in Fig.12. Any excess might get on the points and cause misfiring.
12. Check the condition of the contact breaker points, clean and regap them, and if necessary fit a new set and check the timing and advance and retard mechanism.
13. Check the level of the oil in the gearbox and overdrive unit and replenish as necessary.
14. Remove the combined oil filler and level plug from the rear axle (see Fig.13) and top with Castrol Hypoy (SAE 90 EP).
    After topping up allow sufficient time for any excess to drain.
15. Adjust the carburetter slow running and tune if necessary. *
16. Examine the exhaust system for holes and leaks and replace defective components as necessary. *
17. Balance the front wheels to eliminate steering vibration as necessary. *
18. Check and adjust the steering 'toe-in' of the front wheels.
19. Check the suspension nuts, and the steering nuts for tightness.
20. If wished, change over the tyres to equalise wear and inspect the walls for damage. *
21. Lubricate the washer round the wheelbase spindle with several drops of glycerine.
22. Clean and adjust the sparking plugs.

12,000 Miles Service
EVERY 12,000 MILES (or once every 12 months if 12,000 miles not exceeded)

1. Perform all the maintenance tasks listed for the 6,000 mile service. In addition carry out the following operations :-
2. Remove the carburetter float chamber and empty any sediment present, check the contition of the needle valve, clean and refit.
3. Remove the speddometer cable, clean, and lightly lubricate the inner cable with LM grease or similar. When reassembling the inner cable should be withdrawn approximately 8 in. and the surface grease wiped off. This is so none will work its way into the speedometer head.
4. Steam clean the underside of the body and clean the engine and engine compartment. *
5. Remove the sparking plugs, and fit new ones, correctly gapped.
6. Inpect the ignition leads for cracks and perishing and replace as necessary. *
7. Remove the rear brake drums, blow out the dust, and inspect the linings for wear. *
8. Examine the dynamo brushes, replace them if worn, and clean the commutator.
9. Renew the windscreen wiper blades. *
10. Check the headlamp bulbs and renew them if slightly blackened or if the element sags.
11. On later models fitted with a crankcase closed circuit breathing system, change the engine oil filler cap and clean the crankcase breather valve. All the metal parts can be washed in petrol. The diaphragm should be cleaned with detergent or methylated spirits (denatured alcohol). See Fig.14. Key:- 1. Filler cap. 2. Spring clip. 3. Diaphragm. 4. Metering valve. 5. Cruciform guides.
12. Lubricate the water pump. To do this unscrew the oiling plug behind the pulley wheels and grease sparingly with LM grease. Replace the plug. If the pump squakes a few teaspoonfuls of hydraulic fluid in the cooling system will silence the carbon sealing ring. Fig.15 refers.
13. Take out the air cleaner elements by unscrewing the bolts on the side of the cleaners, and removing the covers and cleaner elements. Clean out the inside of the air cleaners and fit new cleaner elements. Replace the covers and bolts.
14. Tighten the nuts on the rear leaf springs seat bolts.
15. Give ten trokes of an oil gun filled with Castrol Hypoy, to the lubricating nipple (arrowed in Fig.16), on the rack and pinion steering housing.
16. Remove the overdrive (if fitted) and gearbox drain plugs and drain off the old oil. Clean the overdrive filter and refill the gearbox and overdrive with SAE 20W50 (engine oil). Fig.17 shows a funnel in the position normally occupied by the gearbox dipstick. The overdrive drain plug (arrowed) and filter are shown inset.

24,000 Miles Service
EVERY 24,000 MILES

1. In addition to the maintenance tasks listed previosly carry out the following operations :-
2. Check and adjust any loose play in the rack and pinion steering gear. *
3. Examine the ball joints and hub bearings for wear and replace as necessary. *
4. Check the tightness of the battery and engine earth lead on the bodywork. *
5. Renew the condenser in the distributor. *
6. Remove the starter motor, examine the brushes, replace as necessary, and clean the commutator and starter drive.
7. Test the cylinder compressions, and if necessary remove the cylinder head, decarbonise, grind the valves and fit new valve springs. *

40,000 Miles Service
EVERY 40,000 MILES

1. Drain the brake fluid from the hydraulic system. Renew all the rubber seals and flexible hoses. Examine the brake pistons and their bores for scratches and renew as necessary. Refill the system with Castrol LMA or DOT 4 brake fluid and bleed the brakes.

100,000 Miles Service
EVERY 100,000 MILES

1. Give yourself a pat on the back for owning such a great car!

Based on "Routine Maintenance", MGB Owner's Workshop Manual, Portions © Haynes Publications Inc., 1973.