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MG MGB GT V8 Factory Originals Technical - Oil pump priming

Iím having trouble priming the oil pump on my 3.5 Rover engine after a complete rebuild. Iíve packed it with petroleum jelly 3 times and cranked the engine on the starter with the plugs out, plenty of oil in the sump but no pressure and the pump is dry. Does anyone have any ideas to try before I take the sump off to check the pick up?

Geoff King


I took out the distributer and used a short lenth of 15mm copper pipe with one end squeezed to lock over the top of the oil pump drive (through the distributer hole) and the other end squeezed in so that I could put it into the chuck of a battery powered drill. Sounds a bit barbaric but after about 90 seconds spinning the drill started to struggle and up came all of the hydrolics. I dont know if the starter could easily deliver this spin rate even with the plugs out.

frank swinton


Thanks for that. Iíll give it a try before taking the sump off as Iím sure there is nothing wrong with the strainer and pickup pipe.

Geoff King

Did you also top up the oil filter pipe with oil.


I didnít bother, expecting the pump to pull the oil from the sump I wasnít worried about turning the engine over for a few revs with no oil pressure as it was built with cam lube and bearing anti scuff. Now Iíve turned it enough, although probably no more than a total of a minute on the starter motor in 7 or 8 second bursts.

Does filling the oil filter pipe with oil somehow help the pump prime when the flow is in the opposite direction?

Geoff King

One method which I have used to ggd effect a couple of times is to disconnect the pipe from the pump to the remote oil filter at the oil filter end. Then fill this pipe with a really viscous oil and wait for it to drain down the pipe and into the oil pump itself. When the gears in the pump are covered in this really thick oil it doesn't take long to get the pressure up when turning the motor over without spark plugs. Good Luck.
David Daw

There are two pipes running to the remote oil filter. Fill the long one running towards the front of the car with new cold oil (this goes via the oil cooler back to the oil pump base) and keep filling it as it goes down. I even blew down mine to make sure the oil was being pushed back into the pump.
You may like to fill the oil filter filter as well but this wont help prime the pump only possibly speed up the oil pressure gauge or light on initial start up.
The other short pipe from the remote oil filter is the return and you can fill that with oil if you want but it wont make any difference.

Thanks guys,

The drill did the trick, oil pressure almost immediately. The engine fired up for the first time in more than 3 years, runs fine and sounds fantastic but the fans blow their fuse so I couldnít run it for too long. Not long now and the í72 GT, saved from the scrapyard, will be back on the road as a V8 roadster.

Geoff King

This thread was discussed between 17/07/2002 and 18/07/2002

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