Oil pump 3 or 5 lobes

[Theo_NL]

Did not want to risk anything with the oil pump (severe grooves on the 2 moving parts), so ordered new one. I've seen some discussions here about the 3 lobes or 5 lobes, so took the new one apart. 3 lobes!

What would be best: Reuse the old one (acceptable wear?) or use the new one (3 lobes)?
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Thanks,

[bmcecosse]

3 lobe pumps went out many many years ago. Maybe that's old stock - maybe it's a repro ?? Someone reported recently that they got a 3 lobe (I think from same supplier) and internally it was less than a quality product. What do the lobes look like on the 5 lobe pump ? If not bad - that's what i would be using - and return the 3 lobe for refund.

[Theo_NL]

It is repro. It is marked Powertune. Googling leads to PS Autoparts, and they mention County as the manufacturer.

I will make some pictures of the 5 lobes part, think it's ok, but I'm more concerned about the leakage that occurs due to the grooves in the backplate. Will check axial dimensions of housing and inner parts.

[frame][/frame]

[bmcecosse]

I wouldn't worry about the grooves - they probably fit together like a labyrinth...... I suppose you could smooth it all out with a piece of plate glass and grinding paste - and a lot of patience.. It seems that 'County' made your pistons and rings too... never heard of them before.

[les]

I'm sure I've seen a measurement quoted somewhere for the tolerance between the rotor and housing.

[philthehill]

The problem with cleaning up the front and back faces of the rotor is that there is a risk that you increase the face to body clearances allowing more leak past.
Unless you are wanting to shift vast amounts of engine oil I see little problem in using the 3 rotor oil pump for your proposed use and application.
Yes it would be better to use a 5 lobe oil pump but in reality the only difference between the two for your use and application is that instead of having three surges of oil per cycle you have five so a steadier flow of oil and the capacity of the three lobe I would suggest is more than adequate for your needs.
Personally I would not even spend time trying to clean up the old oil pump. As you have the three lobe oil pump I would use it. The alternative is to put the three lobe oil pump to one side and spend out on a reputable make of oil pump. Good quality oil pumps are not that expensive and as I have said before the oil pump is the heart of the engine.
See Mini Spares web site:

http://www.minispares.com/search/classi ... pump.aspx-

[philthehill]

Les

The oil pump clearances quoted are from the Haynes Manual . MINI 1969 - 1982 No: 646 of 1982 and are relative to the five lobe oil pump.

Outer rotor end float.......................................0.005"
Inner rotor end float........................................0.005"
Outer rotor to body clearance.............................0.010"
Rotor lobe clearance........................................0.005"

There is a very good section No: 37 which gives a good description on measuring and checking the pump with illustrations on how to and where to take the measurements but to is to large to post on here and any smaller it is not beneficial.
Phil

[les]

Just found where I'd seen the spec Phil, in the Haynes Morris Ital manual. The only difference from your figures is the rotor lobe clearance---0.006''

[philthehill]

Les
Yes in the Marina Haynes Manual ISBN 990550 73 2 of 1972. But NO nice photos of how to do it.
I notice the illustration is of a six lobe rotor so may have some bearing on the rotor lobe clearance.

Phil[frame][/frame]

[bmcecosse]

I would hope that clearing up the ridges would reduce the clearances - indeed - need to check that a clearance still existed after the 'clearing up'. This is something I have seen discussed in Mini forums - where that end float is intentionally reduced (although 5 thou is not a lot anyway..) to improve pump performance. The previous issue with the type of 3 lobe pump here (I think) was references to the poor quality of manufacture... I would use the 5 lobe - after a bit of clearing up... But as Phil says - if the 3 lobe pump appears to be well made and conforms to the end floats - it will have plenty of performance for this standard engine.

[biomed32uk]

It was the powertune that I sent back, didn't like the look of it.

There is one listed in the Moss catalogue, and I did ask about it, that's a four lobe pump and looks a better quality option. If my fleabay bargain goes wrong that's where I will go back to. Kent cams list one as well, but they cant be bothered to get back to me.

[Theo_NL]

Outer rotor end float.......................................0.005"
Inner rotor end float........................................0.005"
Outer rotor to body clearance.............................0.010"
Rotor lobe clearance........................................0.005"

Measured following (not sure I have the right understanding of the definitions);
Outer rotor end float[frame][/frame]
Inner rotor end float[frame][/frame]
Outer rotor to body clearance: by feeler between outer rotor and housing
Rotor lobe clearance (2 positions):[frame][/frame][frame][/frame]

For the 3 lobe pump:
Outer rotor end float: 0,05mm = 0.002"
Inner rotor end float:0,05mm = 0.002"
Outer rotor to body clearance: <0,05mm = <0.002"
Rotor lobe clearance 0,05-0,1mm = 0.002-0.004"

For the 5 lobe pump:
Outer rotor end float: 0,1mm = 0.004"
Inner rotor end float: 0,1mm = 0.004"
Outer rotor to body clearance: 0,2mm = 0.008"
Rotor lobe clearance 0,15mm = 0.006"

Also calculated the displacement volume of both pumps:
3 lobe: 11,128 cc = 0.67 cubic inch
5 lobe: 11,174 cc = 0.68 cubic inch

[bmcecosse]

Well done with that displacement volume calculation! I guess I would just use the 3 lobe....it looks ok. PROVIDED the shaft is keyed to the rotor? Can't see in these pictures.... Some pumps are only 'interference fit' between shaft and rotor - and not unknown for the shaft to break free..obviously a disaster for the engine - so not worth the risk.

[Theo_NL]

The shaft is NOT keyed to the rotor

I think I have search for a new one. None of the suppliers show any detail of the pump in their online shops.
Anyone a good suggestion?

[bmcecosse]

Do a deal with Phil for his 'Cooper S' pump... http://www.mmoc.org.uk/viewtopic.php?f=8&t=58357 Or - carefully tidy up the 5 lobe pump you have - it will be fine.

[Theo_NL]

Well.. bought a new pump thru a Dutch supplier who sells stuff from Moss. It looks much better than the Powertune.

New and Old (original):[frame][/frame][frame][/frame]

And (sorry no picture): it is a 4 lobe pump...
Measured the clearances, and where OK:
The rotor lobe clearance is < 0,05mm = < 0.002" in all positions.

It fits good, only had to adapt the cover for fitting the original lock tab.[frame][/frame]

[biomed32uk]

That looks OK, I was going with the moss one had my ebay find in the states not come good.

That Powertune thing looks a total piece of junk, many of the parts are of doubtful quality, I have just had to weld a new clutch pedal up to my liking !.

Good luck with the rebuild, finished mine tonight, head fitted and last few bits done. Now awaiting refitting to the car once I have done the gearbox and everything else I want to do.