water pump,

when fitted can you still shift the impellor by hand,

or can it only move by pulley and fan belt with fan fitted to harmonic balancer

It should spin easily by hand without the pulley or fan.

any causes for not spinning.

Siezed bearing, engine sitting for long time and coolant has solidified and locked it up, or plastic fan has deformed and is rubbing on timing chain breather - I've seen all of those before.
Those would be more normal - not sure if say fitting a 1275 pump to an 850 would lock it though.

Whats yours doing? new or old and is it tight or locked completely?

when i fitted mine i was advised to check if it spun after install as you sometimes have to get a file out to enable it to spin freely

lucky for me mine just worked i have a 1275

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1968 Morris Mini Cooper S

I can not spin it by hand, I just bought the engine from someone who said it has a brand new water pump installed.

There is coolant in it from previous owner, I have just fitted a heater blanking plate, can see coolant in it

no fan fitted, just the pulley, and it is not moving.

can you store the engine without coolant to stop this happening again?

just ordered a new pump.

this ^^

take the pump off, it'll start moving as loosen the bolts

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did I tell you that I won a trophy?

you probably have the large impellor type water pump fitted
often they need a couple of gaskets behind, or grind out the offending section of the water jacket/wall behind the pump where it clashes with the impellor

typical situation of someone "thinking" they`re fitting a better pump but not recognising the need to make sure the impellor clears the number one bore/wall/jacket

easy fix tho & better off with the large impellor pump anyways

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

the bolts are to long through the pulley touching the pump even with the fan on

If the bolts are too long fit shorter ones!

hacksaws work really well too...

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did I tell you that I won a trophy?

Should the fan have a spacer too explaining why the bolts are too long?

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"