Hello All, Just picked up our refurbed head looks great! So about to put it all back together again, i hear some people blank off that small by-pass hose from the water pump to the cylinder head, Any advice for or against??

Cheers
TSB

Either, entirely up to you. I have a metro head without the bypass at all. if you decide to go with no bypass you can buy a radiator bottom hose with no bypass. Also you need to drill a few small 1/4" holes in your thermostat as apparently running no bypass will create cavitation in the water jacket. I've drilled 3 holes in my thermostat. No issues in 4 years.

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Lillee - 1969 Morris Mini K

It was found that the location of the by-pass caused cavitation of the pump, so in the later cars it was redesigned and in doing so moved away from the pump.

Some here like to run with them, but I haven't had one in a few of our cars for over 20 years now with no ill side effects, other than having to check a few times after refilling to be sure all the system is full and not having to deal with that pesky hose.....

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blank blank blank blank

I run one and have never had a problem, but I use USA made 1/2" heater hose there, not that damned concertina rubber thingy.

lillee it's the water pump that has the bypass connector, NOT the bottom hose (that one is for the heater)

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I love that paint job, so psychedelic

pain in the ass to replace too if it bursts. i have mine in there, but its heater hose not the flexible hose.

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Aussie Leyland, Aussie Factory, Aussie Mini S.

mine's in there but it's a kevlar hose from minispares....

when the head comes off i think i'll blank mine...

Isn't it there for a reason?

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

Yes, design error

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Too many cars, and too little time.

It's there to circulate the coolant through the block and head before the thermostat opens. Hence the reason Vizard etc say drill a 3mm hole in the thermostat's flange if you block the bypass off.
Metros blocked it off true, however, they have a sandwich plate bypass setup under the thermostat- which Minis don't.

If there was ever a pump cavitation problem with the original A series bypass arrangement, it took BMC/BL/Rover 30 years to find it... it was used on everything from 1951-198?.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I've not had a by-pass hose since 1968. I used to swap in the BL comps blanking sleeve, then when they became unfashionable, just drilled holes in the thermostat.

Can't say I've ever had a problem with this. I run the heater return into the pipe on the water pump and use the UK non heater 850plain bottom radiator hose - the one without the heater pipe sticking up out of it.

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

The trick to the bypass hose ( i believe ) is to change them out before they sh!t themselves, ie: just prior to summer would be a good time , that way you can flush your system out, put on any new hoses that you might need, refill the system with coolant/ inhibitor and you should have trouble free running for years.
Granted ,they are not the best job to do , but if you plan it out and take your time, the
whole job can be done in a couple of hours, and let me tell you the bypass hose is a lot easier to change in the shed than on the side of the road in the middle of summer .

red and yellow and green and blue.

i can see a ....... see a ... water pump.

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Aussie Leyland, Aussie Factory, Aussie Mini S.

I am changing the radiator and hoses, should I do this hose at the same time? Does the water pump/head have to come off to do it?