Some of you may have seen my thread about my oil pressure problems I’ve been having here. http://www.ausmini.com/forums/viewtopic.php?t=54835&postdays=0&postorder=asc&start=0

It now seems like we have an answer but it is a little conserving as it could affect a lot of people. After all the testing we did it left no other real option but to be a defective oil pump Now there are not too many things to go wrong in one as they are a very simple devise, in case people dont know what is inside one.



The problem looks to be that the input shaft that is driven from the camshaft is slipping on the ‘impeller gear’ that creates the pressure as it rotates Now there is no way in any shape or form that this joint should slip.

We have looked at four oil pumps two old, two new and this is what we found:
The new one that I had in the motor when I was having problems when put in a vice you could slip the impeller on the shaft with a shifter at room temp.



The second new one was no better if not worse, the second one was out the packet hadnt been in a motor yet. We tried this with a worn STD rover item out of a old A+ 998 and there was no way in the world you could turn in, even leaning into it with two hands on a 12” shifter. And the last pump was a three or four year old pump out of my last motor and that was a lot tighter then the brand new ones but not as good as the STD rover item.

So we decided to take a look at the shaft to work out if we could pin it someway. So we pressed them out and found something that explains it a bit more.


The STD A+ Rover item has splines on the shaft to ‘lock’ the impeller on were as the aftermarket pumps are just a smooth shaft. Now I do appreciate that if done correctly a shrunk fit item like that should hold no problems but I think the proof that it can be turned by hand shows that it’s not tight enough and to be a bit of a concern.

Even if this is not the cures behind my oil pressure problems I can’t see it helping anything being like that when you think of the force that needs to be transmitted through that shaft to make the oil pressure.

In the end we pressed the Rover shaft into the new impeller with some locktight just to make sure. I’m really hoping that this and the new modified centre oil pick up with fix my oil problem

Thanks Nathan.

yeah, I guess that'd do it - the splines are there for a good reason, oil isn't that easy to push around

I just put a new pump in my 1275, I hope they don't have the same trouble

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did I tell you that I won a trophy?

I believe that GR may have seen the same problem as mine in a big bore race motor not too long ago. GR agreed that there is no way that you should be able to spin the shaft and this could leed to bad things happing.

So this may not just be a problem with small bore pumps as they all may come from the same supplier

Nathan.

WOW

May I ask who makes it??

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Out of the two new ones I got one was from Swiftune in the UK that i got sent over (not made by the tho) there “OE spec high flow oil pump for a 998” and one was from a local supplier in ADL as the same discription.

Both pumps were identical, but no brand.

Swiftune were good about it, they are cheaking some of there stock to see if others are affected, but can not do anything with the one I have unless I send it back to them, and I think that is fear.

For me tho not worth it as I'v used that one to make this good one. Still waiting to hear back from the local supplier.

Nathan.

That would explain it,as we were thinking it may be the shaft slipping could not think of anything else.
Hope it all works better this time around

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4efte powered Clubman
supercharged 998 race car

In the old days they had a key/keyway on the shaft. No way they would slip. They are probably saving $1.00 not putting that in. It's disturbing.

Pete

I am sure GR will post, but his Race motor suffered loss of oil pressure for other reasons, none of which are due to the Oil pump. We pulled it down today and found all was well in the pump and things not so well in the box.

I have had no issues with the two motors i have built of late with there new oil pumps. So maybe you have caught a couple of bad ones. I dunno.

Cheers
Aaron

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the one I pulled out of my motor is sitting on top of my rubbish bin - I'm going to pull it apart to check, I'm pretty sure it's the same as the new one I just put in

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did I tell you that I won a trophy?

Bit of a noob question when it comes to oil pumps but why do we put a new one in when we build an engine?
Would we be better off pulling apart the old one and rebuilding it so we know it's good?
And with those new ones you have I'm sure you could either machine in a key-way or simply weld it.

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Respect mine and I'll respect yours.

The oil pump relies on internal clearances to be effective. Once it wears it will pump less pressure. Most of the pump wear in Minis comes from swarf from the gearbox passing through the pump as it is before the filter on the oil's path. It is much cheaper to buy a new one than it would be to try re-metalling and re-machinig an old pump.

Pete