MG Car Repair: mgb oil pressure, oil pressure gauge, oil gauge

Question
just finished complete new rebuild on mgb started right up, sounded great, no oil pressure zero what's wrong

Answer
Hi Terry,
If you run an MGB for more than several seconds with no oil pressure you will destroy the mains and rod bearings and if you were able it keep it running for several minutes, it would destroy the pistons too.

You should always on any rebuild or any major repairs to an engine (any engine) you should spin the engine with the plugs out until you see oil pressure and if it does not indicate pressure within 10 to 20 seconds of spinning you need to find out why.

This can happen when the oil pump was not properly lubed and none of the oil galleys were filled with oil and the oil filter was not prefilled with oil etc.

If you didn't run the engine but a few seconds and shut it down you may not have damaged it so do this.

Remove the oil gauge feed pipe (rear of the block on the right side) and and the spark plugs and find a piece of either a clear plastic hose or a rubber hose and a small funnel. Fit the hose over the block fitting. Fill the funnel or the clear hose with engine oil and hand rotate the engine BACKWARDS!. (counter clockwise as you face the engine from the front. As soon as you start to rotate the engine backwards you will see the oil level in the funnel or plastic hose go down. Keep rotating the engine backwards and keep filling the hose or funnel until you have used up at least a full cup of oil. If you didn't prefill the oil filter be sure to run at least 3 cups of oil down. The oil should move down instantly because the oil pump is turning backwards and you are filling all of the oil galleys except the feed to the rocker arms which can wait. This also fills the oil pump and is important as an oil pump can get vapor locked if it was not prefilled or prelubed with a thick oil or lubed with a thin grease. After you have done this, connect the oil pressure gauge line up and spin the starter with the spark plugs still out and attached to the wires and laying on any metal part of the engine. (or you can just remove all of the wires on the (+) post of the coil.)
You should see oil pressure almost instantly. You should see about 35 PSI or better with the starter.
Howard