simon k wrote:
Best thing to do (other than my method below) is to leave the spark plugs out and turn the engine over with the starter motor until oil starts coming out of the rocker shaft. The engine will spin fast for a little bit until it picks up oil pressure, then slows down and as it has to push against the oil pressure. Also a good idea to "reverse prime" the oil pump by taking the oil cooler/filter outlet off the block and use a funnel to fill it (the outlet from the engine that is) with oil. Put the car in 4th gear and push it backwards to send the oil back down into the oil pump and pickup pipe. Do it a few times and you can be sure that the oil pump has oil in it as they can "air lock". Early this year I hadn't used my car for a few months, I started it up and there was no oil pressure, I left it running and nothing on the gauge. I took the oil filter outlet off the block and it was dry, turned it over for a bit and nothing came up, so reverse primed it as described. Turned it over on the starter and oil pressure came up, started it and no issues.
However, I have a pressure tank I use to fill the oil galleries on a new engine build. The tank has a hose that screws into the oil pressure gauge outlet on the block. I put about 1l of oil in the tank, then pressurise it with the air compressor, then open the valve on the tank and the oil goes into the engine under pressure. You can hear it bubbling through the block and popping air pockets. After re-pressurising a couple of times oil goes all the way up to the rockers, through the crankshaft, everywhere. Basically the engine has oil pressure before even turning the crankshaft. I used to borrow one off a mechanic mate of mine, but then I bought/made my own.
However, I have a pressure tank I use to fill the oil galleries on a new engine build. The tank has a hose that screws into the oil pressure gauge outlet on the block. I put about 1l of oil in the tank, then pressurise it with the air compressor, then open the valve on the tank and the oil goes into the engine under pressure. You can hear it bubbling through the block and popping air pockets. After re-pressurising a couple of times oil goes all the way up to the rockers, through the crankshaft, everywhere. Basically the engine has oil pressure before even turning the crankshaft. I used to borrow one off a mechanic mate of mine, but then I bought/made my own.
That’s particularly clever Simon.
I have a non Mini engine to build and I think I’ll prime it this way.
I once built a P76 V8 and the “book” states to run it at 2000 rpm until the oil flows out of the rockers. It took a couple of minutes before all of the followers and rockers went silent. The engine performed faultlessly for many years. But I had drowned every part in a mixture of engine oil and molybdenum disulphide during the build to ensure everything was slippery
