Do they make a model for a 1970 MK II Cooper S? That'd fix my cooling problems !!

Yep no norries, car crushed then no overheating problems

Edit: Woopps! That was 5000 Gallons per sec ! (it was for the US)

This one would fill your avaerage olympic pool in about 30 seconds - give or take.

EDIT: Appologies one very important omission that I made (oldtimers again!). All the Minis that have had the by-pass removed were also fitted with a header tank.

It is poor engineering that these were not factory fitted to the Mini (as they were on Morris 1100's and Mokes and just about every other BMC / Leyland vehicles). A lot of 'mysterious' overheating problems which seamingly have no cause can be fixed by installing a header or overflow tank. They do not need to be particularly big (as the Morrie 1100 one is a bit hard to find a good place to put sometimes), about 150 - 200 mls usually does it.

Without a seperate header tank, the system airates. This does lead to errosion and heavy wear of all cooling system components. It also drastically reduces the efficiency with which the pump will work at.

Got more 'interesting' info on pumps and mini cooling systems and by-pass hoses coming up shortly.

Awesome We have some 2.2m diameter sewer mains that I want to walk down, but we rarely do inspections now

I don't have much experience with header tanks vs no header tanks, but I imagine having a header tank would cut down corrosion a bit by not allowing oxygen into the system. I don't have experience with closed systems either, but I agree that having air in the system would probably reduce efficiency because the air can be compressed as the pump is pumping. Maybe it is time to whack a coke bottle header tank in my car

thats what i use

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

Yeap, it'll get the job done (for a header tank) just make sure that you use the radiator cap with the correct reach (depth) and (most important) that it has an upper and lower seal.

Hi richarde,

I'll be coming back with some test results, however I have been giving some of your info some thought;-



The cooling system is a closed one, so the HP taken to drive the pump would be very small and even smaller on a race engine since it is the norm to run a blanking sleave in place of the thermostat. Also, when the pump does caviate, the HP needed to drive reduces even further, so less HP to drive but this doesn't help with cooling Yes, I agree, but the power taken would be very small in the first place so any gain would be very very very tiny, although more power would also be gained by absorbing less in the fan.



Agree 100%, although there can be a few other causes, but this is what we are all on about here. Caused through vapour presure.



I do agree with what you say here about flow and valves being around the 25% mark, however the bypass system has a cross section area of about 75 sqmm and the primary system about 380 sqmm (so about 20%) however considering flow dynamics and actual pipe flow rates, it would be less than 10% flow through the bypass system to that of the primary system.



Yeap 100% here

I've done some very simple tests and I think it fair to say not conclusive on their own as it was done on one sample, however I have had further discussions with a pump guru on the subject of the by-pass hose.

Here's what I found. I have to say that it was not what I was expecting.

When the Thermostat is closed, the flow through the by-pass is almost Nil. It does however start to flow quite quickly just as the Thermostat begins to open and the slows to almost no flow as the Thermostat gets to the 20 - 25% open. Pretty crude, but that it. What I did also find that it caused cavitation, just as the Thermostat was opening. I was not expecting this and at first I thought that the seal on the pump was faulty (drawing air). Changed and the a repeat result. Hmmmm......

I have since spoken with one of the Pump Designers (at the company where I'm involved with the testing). He did confirm that it is a very poor design to begin with and that by having the by-pass where it is will cause cavitation, it's way too close to the impeller. I then showed him the metro set up (no by pass on the pump / head) and he felt that it was because of cavitation that they moved it. He also looked looked at the mini set up on and off over a couple days and he really did feel that having the by-pass was not necessary but he did say that (after more sensibly locating it so as to not cause cavitation) it would need to be thoughly tested before he would be drawn one way or the other.

Interesting point there about the bypass causing cavitation.
I have searched on various forums, but have yet to find any actual figures on a standard mini water pump flow rate. Has anyone ever tested it? Even a figure for a fixed 3,000rpm would be great.

Some UK race cars get away with 18L/min electric pumps normally used as auxiliary pumps in some Fiats/SAABs/etc. The biggest problem with a belt driven pump is that it flows very little at idle, hence the need for at least one cool down lap to remove heat soak after a few hard laps.

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Too many cars, and too little time.

Although this has been explained to me and I've done some basic tests, I still remain on the fence with regards to cavitation and the by-pass hose. I do put it out there that I am not a 'fan' of the by-pass but then thats me, some do like them.

Someone did suggest that the by-pass could have been fitted only to provide some coolant circulation in the case of a siezed thermostat....

I don't have any flow figures for the pump, however I'll see what I can arrange. I have heard from some that the optimum shaft speed for the pumps is actually 2000 RPM.

The best place for the by-pass hose on our Aussie minis is to simply take it from the heater outlet (at the back of the head) & then add the other end of it into the top tank of the radiator (& yes that means having some one solder a pipe fitting into the top tank)

But with the original by-pass hose fittings blocked off & this new by-pass hose fitted, then 4 wonderful things happen--> One: you don`t blow/split by-pass hoses ever again & if youve even replaced a std by-pass hose before i`m pretty sure you will love me for suggesting this mod

two: you get a wonderful more "EVEN" heat distribution across the entire length of the head, far better for all things runing smooth & reliable

three: when you`re stuck in a traffic jam , in 33deg heat day, & it`s going to pop it`s head off just sitting there idling away, hardly any water moving on idle, hardly any air moving through the rad cause it`s idling , & then what-ever air there is moving is damn hot air,,, so having "HOT" water taken from the back of the head (hotest point) & having it cooled through the rad is an absolute blessing

four: instant lack of cavitation as the whole system actually flow more easilly

If anyone now trys to sugges tthat the engine will take too long to warm up,,, well 5mins is too long is it?

don`t argue with me ok??? it`s the only way to go in my books & you can retain your thermostat for correct regulation of temp,,, as it`s meant to be.

blanking sleaves were "originally" invented to help stop a thermostat failure while racing,,, not so much to regulate temp,,, cause the hole size in the blanking plate would have to be able to become smaller or larger """IF""" it were to be able to regulat the temps correctly across a whole wide spectrum of driving conditions,,, where as a race car is generally running flat out, so a "certain" sized hole is the right regulatiopn for that engine speed & """ALSO""" because there is no thermostat fited , well it can`t fail then can it??? If it got stick shut then your race is over

get it?



& remember,,, No arguing!!!!!!!!!!!!!!!!! If you dis-agree with me on this, then no matter what you say---> I won`t believe it







(unless it makes more sense)

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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.

but....but....but.....oh bugger it!!!

I haven't done the check on what you suggest here Matt, however that is pretty much what I have ALWAYS ran on the mokes and some minis.

Never ever ever ever had a problem....ever......

ever???

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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.

I was just wondering, have you ever had a problem?

Only here, but that's for another day....................................Oh and women...........................................................................