948 Oil pump question

[MsRose]

Morning all

I’ve been watching a few engine rebuilds (as I’m in the middle of one) and my question is regarding the oil pump. I notice a lot of people mention de burring them.

I purchased mine from ESM and wonder if I really do need to do this?

Help and advice very much appreciated please.

[philthehill]

Whilst it is nice to do - there is no real benefit in just de-burring the oil pump. It does not increase the oil flow to any great extent. Flow as well as the ability to create oil pressure is required.
Reprofiling the inlet and outlets of the oil pump does increase flow and the ports of the oil pump fitted fitted to my Minor were reprofiled by Manx Racing to increase the flow but that is on a high performance engine where flow is a major element of the oil cooling process/requirement.
If you feel the need to de-burr the oil passages just do it as you have nothing to loose. Just make sure that you remove all de-burring rubbish otherwise the pump and engine will not last long.
Good luck and please let us know how you get on.
Phil

[MsRose]

Thanks Phil for such a quick response.

I did buy the good quality one, which stated no modifications required. It's just that many people were saying the same thing and it kind of got me worried.

[oliver90owner]

Please can you explain how a positive displacement pump, pumping an incompressible liquid can be increased volumetrically. It just seems a bit difficult to do that by just removing burrs - unless cavitation is occurring on the inlet side.

[philthehill]

Personally I would not worry about the pump just fit and forget.
I would prime the pump with some engine assembly fluid before fitting. When the engine is fitted and ready for starting I would remove the spark plugs and turn the engine over to get the oil around the engine and the oil pressure up before firing up the engine.
You will not increase the capacity of the pump in removing any burrs but with a bit of extra work you can help the flow of oil into and out of the pump.

[Sleeper]

Oil Pumps, you may enjoy this... Mr A.C.Dodd

https://www.youtube.com/results?search_ ... d+oil+pump


John ;-)

[philthehill]

John
A good video.
Though for normal road use a good quality oil pump is adequate but saying that always fit the best oil pump you can procure.
The oil pump fitted by the OP:-
https://www.morrisminorspares.com/engin ... it-p830266
By all means check the clearances as per the video and if the clearances are considered excessive send the pump back to the supplier.
For the home mechanic without engineering & machining facilities there is little they can do to get to zero tolerances other than order a AC Dodd zero tolerance oil pump.
As stressed in the video and in my comment above - make sure that any dirt/swarf including if necessary any burrs are removed from the pump before use and prime the oil pump with engine build lubricant.
As an aside - I always try and fit a oil pump which has the rotor Woodruff keyed to the drive shaft as there have been cases where the rotor being just pressed onto the drive shaft has come loose causing a total loss of oil pressure.
Happy oil pump selection and fitting.
Phil