970 S oil pump problem

[Cables]

My friend is currently assembling a 7 port 970 engine and has come to halt now due to problem sourcing an oil pump. When he told the company he bought the head from what he wanted from the engine they recommended a Kent 286 and supplied a pump but unfortunately it's the wrong fitment (4 bolt not 3 bolt).

We're looking for a slot drive cooper s pump, I notice mini spares do a performance billet pump for the s but I need a slot drive

[mk1]

This is a common problem.

The best bet is to drill & tap the extra holes in the block & use a 4 bolt pump. The Minispares one is excellent, but it does take a bit of lining up, follow the instructions.

I very much doubt that you will find a slot drive 3 bolt pump anywhere!

M

[Spider]

I'm quite sure there is no such animal.

Use the '4 bolt' (which may only be a 2 bolt), just spot, drill and tap the top two holes.

[cpr1]

If you have the old one, i can supply you genuine three bolt ones, from the small bore engines, but you'll have to replace the shaft, it is removable, on the S pump it is longer but the gear and housing are the same, if I'm not wrong .

See link to photos of pump.

Guess i should have some shafts machined, my friend got and engineering shop!

http://s639.photobucket.com/user/raymus ... Oil%20pump

[Cables]

My friend actually now has a minispares evo s pump, it looks like we could change the shaft for a slot drive, but when he phone mini spares I don't think he got much sense, wonder if rich can get in touch as it looks like it just a matter of knocking a roll pin out and swapping the shaft.

[rich@minispares.com]

you can buy a slot drive (metro) minispares evo pump C-AEG412

I certainly wouldn't get involved in swopping bits around on the pumps, as it would invalidate any warranty with them and might damage the pump

[cpr1]

any one got a knackered s pump lying around or a shaft, for measurements, if I can have the shafts made, the housing supply is so to speak endless but the way if you havn't noticed they are genuine Leyland.

[mk1]

I'm not a fan of swapping shafts on pumps.

The oil pump on an A series engine is one of the most critical components & was always if anything a bit under spec for the job & prone to premature wear & failure. Once you start swapping shafts from one pump to another you are simply introducing another layer of poor fit & misalignment to the scenario.

Anyone can drill & tap 2 extra holes in the block easily, this enables anyone to use any pump on any block at any time easily & safely. This was even Mr Vizards recommendation back in the early 1070's when he wrote HTMYM.

If there ever was a no brainer, then I reckon that this is it.

M

[cpr1]

Most of the knackered pumps I've seen,it is the gear,housing that holds the rotor and the rotor that wear and get scuffed due to some foreign debris usually from the gearbox

any one got a shaft for measurements ?

[mk1]

I have if you are desperate for one.

But I would love it if you could explain to me how it is easier or more sensible to reverse engineer a DIY pump shaft, dismantle a perfectly good pump (thats not designed to be dismantled), swap the shaft & re assemble the mismatched bits. Than it is to drill & tap 2 holes in a block 1/4UNF.

[rich@minispares.com]

I have if you are desperate for one.

But I would love it if you could explain to me how it is easier or more sensible to reverse engineer a DIY pump shaft, dismantle a perfectly good pump (thats not designed to be dismantled), swap the shaft & re assemble the mismatched bits. Than it is to drill & tap 2 holes in a block 1/4UNF.

and hope that the new shaft never comes loose and kills the engine

(which I have heard of happening on a 'home made' oil pump)

for the cost a new pump, is it worth the risk?

[Andrew1967]

Whilst I'm not disagreeing with you Mark and Rich about DIY pumps, Concentric oil pumps certainly can be dismantled for inspection and tolerance checking and it's not difficult to change the shaft on the rotor. They are a press fit and if the fit is satisfactory and the shaft is pressed to exactly the same position (internally) as the shorter pin, then I can't see a problem.

Maybe I've been lucky, but I did this with my knackered S pump and a NOS Concentric 850 type pump and sold my 'genuine' NOS S pump. 7000 miles later and no problems at all.

Personally, I'd rather bolt an original three bolt pump to my block than drill another hole or two and risk a f**k up

[Cables]

There is contradiction here though with people saying it is a common problem, and then saying there is no call for such a pump?

We inspect the internals of pumps as a matter of course now as a friend of mine showed me a brand new pump he was about to fit came supplied with swarf in the pump, luckily he spotted it before fitting. I am not saying it knowingly supplied like this by any specialist but it would have destroyed the engine within seconds.

On home build engines not supplied by specialist fully built i would say it impossible for said specialist to offer any guarantee on any fitted parts, as they have no control of how it was fitted, running in etc

[rich@minispares.com]

There is contradiction here though with people saying it is a common problem, and then saying there is no call for such a pump?

I think that if your building a 'competition' engine, then a four bolt pump is a must as it ensures that the pump body is fitted tight and square to the block


the problem with a two bolt pump is that the gasket can get sucked into the pump / start to lift and cause pressure problems.

the two bolt pump its self is fine and is perfectly adequate from a pressure / volume point of view - I ran one for years on my race car, but have had issues twice with lifting gaskets (one time was my fault as one of the bolts was too long...), but a pump that is fitted with four bolts has much less chance of any issues.

whilst im sure that competent people can swop the drive pins, its just not something that I would feel safe suggesting as a viable option to 'normal' people - 'you told me it was easy to do, now my engine is wreaked as the pump failed.......'

[CooperTune]

Not to start a fuss, I have held on to just about every part I have replaced on a mini for years. When I still had a stock of NOS pin drive ST cams and no pumps to match I have pressed shafts out of old pumps and into new rotors. Some required broaching a key way into the gear. Some required drilling a small hole between shaft and gear and tapping for a small set screw. Having access to a full service auto machine shop makes such things seem simple. Sure drilling and tapping the block is simple as well. I try to give the customer what he asks for. Sure I try and lead them down a better path, some I just do as ask. Steve (CTR)

[abri]

Rich, on my newly rebuilt 1275 S motor I used the original three bolts to hold the new Minispares Evo pump in place. The bottom one didn't fit through the pump hole properly (only the thread went through), so we drilled it out to 6mm. Do you think that would be OK?

[rich@minispares.com]

it wont be an issue - as long as its all clamped down equal