Priming the MG Engine Oil Pump
By D.P. Houser
Medina, OH
Let's say that you've just put that rebuilt engine in the car, finished the wiring, and are ready to crank it over. All of the normal checks were done and all that remains is to fire the engine and set the carburetors, and the final adjustment with the clutch. Now if this were a domestic V-8 you could prime the oil system with an electric drill and an extension thru the distributor, but you've got a British Leyland motor (MGA, MGB, or Midget) which doesn't allow such priming action. With the ignition off, pull out the starter knob and allow the engine to crank until you see normal oil pressure (normally five to ten seconds). But what happens if the oil pump has lost it's prime? The pump resides above normal oil level and once it is really dry it may not draw the oil upward. Now what? DON'T PANIC! Try this trick that a B/L mechanic and ex-Midget racer suggested:
1. Remove the rearmost external engine oil connection on the right side of the engine. This will be the external oil line or oil cooler line.
2. Remove the spark plugs.
3. Place the gearbox in a forward gear and release the parking brake.
4. Jack up and support the rear of the car so the rear wheels can turn and block the front wheels (for safety's sake).
5. Now with a helper feeding oil into the engine oil train though the rear oil hole in the block that you exposed in step 1, rotate the rear wheels in reverse. Your helper can squirt oil in the hole with an oil squirt can or through an overhead can with tubing. The object is to reprime the oil pump by backfilling the gallery.
6. After feeding at least a pint of oil into the engine, reconnect the external oil line and to crank the engine (ignition off). If you still do not get any oil pressure, disconnect the oil line and again backfill the gallery.
If, after several times of backfilling the pump, you still do not get any oil pressure, good luck. You may have to drop the engine pan and remove the pump.
This trick of backfilling the oil pump worked for me after adding only one pint.
Also, be sure to check the oil level after you get the engine operating. You may need to drain some oil to reach the proper level depending on how much oil you added in the backfilling process.
(David will receive a gift certificate for his contribution.)
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