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MG Midget and Sprite Technical - Priming The Oil Pump

Being in the process of resurrecting a 1974 midget that has been in storage for four years, I'm about ready to try to crank the engine over to see if I can get some oil pressure. The new oil filter was filled prior to installation, plus the valve stems and cylinder bores have had oil poured into them and the engine turned over by hand, just to play it safe, but I'd prefer to prime the oil pump before trying the electric starter with the spark plugs removed and the power to the fuel pump disconnected. I've done this before with an A-Series engine on the bench, but never with one in the car. Any tips on how to prime the oil pump with the engine in the car?
Stephen Strange

I've been told that the pumps don't need priming. However, when I was desperately trying to get oil pressure (see below*) in my reassembled MGB engine I squirted oil down the top oil cooler hose orifice (have the A series got one of these - maybe an outside pipe connecting to the oil filter housing?), and also the block oil gauge take off.

* I was never going to get oil pressure in a million years because I'd used the wrong oil pump gasket that was letting in air, which meant back off with the sump........
Peter Allen

Steve. Nice to see that you still visit from time to time. Hope all is well.
Like Peter, I have never had to prime an oil pump, either in a newly rebuilt engine or in one being brought back on line.

Les
Les Bengtson

Stephen,

On the left side of the engine, behind the carbs at the back just above the water drain petcock is a little hex bolt. Unscrew that, pour in some oil, replace the bolt and crank it. Although, since the engine hasn't been apart, you shouldn't need to prime the pump. It may take a few seconds but you should get pressure using your method.
Martin

For info only, a (UK at least) 1974 will have an engine block drain plug and washer rather than a draincock. Number 2 in image below.


Nigel Atkins

Stephen, I couldn't get any pressure when I first tried turning over my 1275 following its rebuild. I thought I was going to have to take it out again to prime the pump (I'm sure I've seen filling with petroleum jelly recommended somewhere as an aid to priming after a rebuild) but I decided to sleep on it.

The next day I detached the banjo union at the rear by the distributor and poured oil in. I even remembered to tighten it up again before trying the starter! The pressure came up immediately and I breathed a big sigh of relief!

The banjo's easier to get at than the plug behind the carbs.

Colin
C Mee

The oil priming port was deleted on later 1275 blocks so it's unlikely to have one so banjo bolt the easiest option.
David Billington

Yes, the banjo bolt. If the engine is original, it will be a 12V lacking the priming bolt behind the carbs.
Bill Bretherton

Les-
I lost your Email address years ago when my computer got a virus. Do you mind risking posting it here? We've got some catching up to do!
Stephen Strange

Stephen there's an email addy on Les' custompistols.com website, should work?
David Smith

Does anybody out there know the torque specification for the banjo bolts? I don't want to foul everything up by over-torquing!
Stephen Strange

I don't think there is one Stephen.

Just good and tight, noting there is a flat copper washer either side, which does the sealing.

I've never torqued mine, and never had it leak, or stripped the thread.
anamnesis

This thread was discussed between 03/03/2022 and 04/03/2022

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.