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MG Midget and Sprite Technical - Who's oil pump for a 1275?

Just took apart and inspected the oil pump from my 'other' spare engine. Although it was giving good pressure before the strip, it's got a lot of scoring, and since it will be in a long time, I'm going to replace it.

So. Who's oil pump to buy.

The last one I bought was the original 4 bolt concentric engineering pump. Who's are as good as the originals?

Sussex are £23.78 (inc delivery £6.50).

MED are £35 (inc £10 delivery).

Has anyone used a sussex pump recently and is it good, well made and delivers good pressure?

Is there any reason not to save 11 quid by buying from Sussex? The Sussex and med pumps look the same pattern.
Lawrence Slater

Hi Lawrence
I had all sorts of oil pressure issues when I changed my pump which was as a result of replacing the camshaft with a new one and I had to go to slot drive rather than star drive. The engine prior to changing pumps ran 70 psi at 3000 plus rpm and 40psi at idle.

I fitted a pump from mini spares (£17.00 plus pp) and pressure went down to 60psi (just) even at 5K rpm and 20psi at idle. Not bad figures but the original pump was at least 12 years old so I expected better. A problem with the incorrectly supplied thrust release bearing(sound familiar!) meant another engine out so I bought a pump from MED (£30.00 plus PP)

The two pumps looked identical even carrying similar blue stamped identification markings. BUT, the MED one delivered the same pressure as the original star one. I have no experience of the sussex ones but can confirm the MED ones seem ok. You pays your money etc etc!
Bob Beaumont

Ive got the med in mine, never had an issue

Prop
Prop and the Blackhole Midget

Lawrence,
I recently fitted a Sussex pump and have now got HEALTHY oil pressure:)
Had no concerns with the fitting either.
Glynn
Glynn (1275RWA) Williams

Hi chaps,

Like you Bob, I'm used to having high oil pressure, and might worried if it dropped to 'only' 50 psi. But that's actually 'normal'.

I rang Sussex, and from the description, they sound like the same steel backed pump.

Since I only ever use on the road, I'll probably go with the Sussex pump, as I need other stuff too, and if that does cause trouble, I'll buy the MED pump.

Btw. What's so special about having a steel backed oil pump? Is this because they are only 2 bolt fixing now, and the steel back keeps it flat or something?
Lawrence Slater

""Btw. What's so special about having a steel backed oil pump? "

They are blessed by the love of kittens before leaving the factory

Prop
Prop and the Blackhole Midget

I think they are all steel backed for the 1275 now. I did have a NOS BMC star pump made by Holbourn Eaton until recently and that was a two hole fitting with a steel back. Perhaps cheaper to manufacture?
Bob Beaumont

Cheers Bob.

Pussy pump Prop? ;)
Lawrence Slater

We sell quite a lot of pumps and find that there's can be a lot of production variability in the clearances in a minority of pumps. We have found we need to check them all and bin the sloppy ones and mutter the C word to our suppliers.
So I'm not surprised at the varying results stated above.
Paul Walbran

What do you check Paul? Is it the internal clearances between rotor and annulus? Being serious, so no smutty remarks please. lol.
Lawrence Slater

got a workshop manual Lawrence? - it's in there...
David Smith

Annulus brings to mind its immediate mate in an overdrive set-up ... the sliding member.
(Sorry Lawrence, I couldn't resist!)

OK what I check: bigest variation is mainly in the end-float: grab the shaft and see how much is moves in and out - too much would let the pressure escape round the sides. Then yes, check the rotor clearances if the end float is OK.
Paul Walbran

Sliding members? What are they then? MG owners on ice? lol

Hi David. Yup I know about the clearances, but wondered what area of the new ones was suspect.

Cheers Paul. If the endfloat is too great on the new ones, I might as well stick to an old one.

5 thou" quoted endfloat max. Mine is less. Also in the w/s manual, it suggests that the pump cover and body can be lapped to reduce endfloat.

Rotor clearances are, -- outer to body 10 thou max, rotor to annulus 6 thou max. Again mine are within limits, but the rotor and annulus are badly scored.

I've seen a new rotor/annulus set on sale, but it's expensive. Doesn't seem worth it.

Well I've ordered one from Sussex, so I'll see how it spec's up against the w/s manual, and my old one.

It used to be so simple running these old bangers, but if now all the spares are being made substandard, I'm getting close to getting shot and buying a modern.
Lawrence Slater

This thread was discussed between 10/06/2015 and 12/06/2015

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