Todd:

Do you have an oil temp gauge?

It is pretty hard to tell if you need a cooler unless you have a accurate gauge.

Terry

Maybe this is just me but so many people told me to take out the oil cooler that I did it and now almost never go above half on the temps.  A substantial reduction.  I did water wetter at the same time so can't say for sure, have no explanation for it.

Err let me think for a minute and re cap if you lived up to your part of the deal hmmmm ????. The answer is NO YOU DIDN"T so i will hang on to it until someone else more deserving can use it.

I have a theory about common sense...sense isn't that common.

Mal , send me the abutement plate that you promised to send and we'll be friends...

Bull$hit .............

mal, i use common sense over theories.... (Theories are made by Humans and only humans can correct these theories using his common sense)

don't get intimidated by theories or worse, worship them.

Last of the carbed cars and the early spi's Terry.

Boison you are wrong again, imagine that !!!!!! As you have not researched any of the information on the threads you jump into why don't you at least google this stuff before you post misleading crap up on the board.

extreme heat within the engine needs to be regulated to maintain the optimum temperature, an oil cooler with fan and connected to a thermostat is the way to go.  if the oil in the engine gets too hot, the thermostat kicks in and turns on the fan to blow air to the oil cooler and maintain the temp.. 

jizz, zip, how can an oil cooler damage an engine?? it expels extreme heat out of the engine.  heat is fine, but extreme heat is another story.

it's not that the oil cooler can make the oil cold if that's what you think, it regulates heat fyi...

and wait, i'm at work, as soon as i get home i will post pic of my controversial,sought after 38year old spanking rock solid sump guard.  BTW the steel used on my sump guard is same quality of  steel used in the Alcatraz prison cells in san francisco...so durable, you can't even saw it.

I think there is no question that an aux radiator is warranted in some situations.

I would love to see more detail of the 1275 Gt radiator in this BAT listing:

//bringatrailer.com/listing/mini-clubman-1275-gt/

I am wondering if that is the stock aux radiator:

I do think that during the 40 years of production, cooling systems benefited from factory modifications.

At some point an aux fan was added for idle assistance, not sure when and what models.

The last version used the front mounted radiator which seems to be more efficient and it uses an electric fan.

My front radiator car has been through 108° F(42-34 ° C) temps. No question it was hot, but the stock temp gauge sat above the middle line and the oil temp(stock electric) got to a little over 120° C.

In the bay area we rarely see temps over 100° F. Yesterday; about 85 degrees, 45 minute cruise on the freeway, 3800-4000 RPM. 62 psi oil pressure, about 100° C oil temp and temp gauge just below the middle(stock gauge really only useful for relative values).

Terry

An indicator of when an oil cooler may be helpful is falling oil pressure while under load when driving in hot temperatures.

NOTE -That 998cc short block is still going strong today...18 years after the oil pressure fell & coolant temperature rose while climbing in the hills of southern Oregon on the I5 enroute to MMW 1997...with the original main & big end bearings...35 years after the engine was built.  It was after the 1997 trip that the power unit was treated to an extra rad and oil cooler for the heavy work on long trips...in hot weather.

I agree an oil cooler may NOT be the right solution, ought NOT to be an automatic solution...however, they are so easily blocked off that they can be exposed to the airflow when needed.

Before tossing sparkly oil coolers at the car, you have to detirmine the actual oil temperature in the sump.
Most likely, you would do more damage than good by installing one.

 www.minimania.com/Oil_Coolers

How about maybe you do some research before tossing out bad advice.

BTW, Still waiting on pictures of the multi colored sumpgaurd attached to the pink wonder..... Doubt if we'll ever see that.
 

Jwakil,

Once you sort out a solution, please share it with us  I'm in FW and I'm facing basically the same situation as you.  It's bad enough driving in and around Dallas when it's 104 degrees.  But what do you figure the temp is when traffic stops on I-30 under the mixmaster?  110?  120?  I place stock in what Hunter described, similar extreme temps in AU or Death Valley.  And he noted a 1275 based motor.  Recently I had a good look at a well sorted Mini race motor and that guy used an aux heater core up front.  Not because of high compression, timing, jetting or non stock fan shrouds.  Because he ran several times per year at Texas World, now closed.  The Chinese Wok of racetracks.

So I'm thinking aux heater core plus electric fan and for good measure, another look at a way to shroud the header from the side mounted radiator. 

Please for everyones sake get back in the box.

you know what, instead of putting your time and money on installing an auxillary radiator why not install an oil cooler with fan?

just think, the cooling system only involves cooling the sides of the combustion chamber,that's only where the coolant travels in the engine, WHILE the oil travels from the sump ,crankshafts, cams etc. so in effect if you cool the oil down,lots of engine parts heat will decrease dramatically., although oil coolers cannot work by itself, it needs to work with the conventional coolant radiator side by side. imo

thinkin' out of the box

Why didn't you say you designed pumps and coling systems?

You are over-thinking the issue. The Mini engine was designed in the 1950's and was based on a much older engine - some say from a tractor. I'd bet it was designed more by trial and error than by calculation using formulas. You probably won't get  the cooling flow parameters for the engine, unless you measure them yourself.

Perhaps you should consider the engine as the pump housing, with one input (the lower rad hose connection) and two outputs - the t'stat net opening when fully open, and the heater valve. From there, you can see all of the coling circuits if you open the bonnet. You can calculate the resistance in each hose based on its inside diameter. Other than that, you probably won't find a cooling system diagram or resistance parameters - Minis just are not that sophisticated.

I've worked many years designing pumps and cooling circuits.  We always measure the flow resistance or impedance of the circuit by measuring the pressure drop across the points we are interested as a function of the flowrate of water through it (measured via a flow meter), so we generate a deltaP vs flowrate 'impedance curve'.  You can then superimpose on top of that your pump curve which is basically the flowrate the pump can generate for given pressure differentials across it.  The intersection of these two curves gives you your operating point.  Now if you have a multiple channels in parrallel, the flow will be divided amongst the channels based on the flow resistance curve for each channel. I agree the radiators are probably very low resistance, and the hoses are probably the dominant components, but not too sure about the engine block.  If I introduce a low resistance path in parrallel with the engine block, I might be decreasing the flow in the engine a lot.  Anyway, once I look at the diagram I think I can figure it out.  I will be looking at the non-cooling causes as you suggested as well.

OK. The gist of your thought is "resistance to flow" and water taking the easiest path. Lets look at it this way:

• The water pump in an A-series engine produces very little pumping pressure. It is an "open faced' pump where the the impeller is actually inside the engine block. It basically sucks on the return hose from the bottom of the rad. Resistance to flow is proportional to the velocity of the fluid, not pressure.
• resistance to flow in a pipe or tube is a factor of both its length and diameter. A long hose will have more resistance than short hose of the same diameter. As noted previously noted, the cross sectional area of a Mini heater hose is about 1/12 that of a rad hose. Ignoring radiators for the moment, rad hoses are maybe 18" to 20" long. The path of heater hoses from heater valve through an aux. rad, then back up around behind the head and down to the connection at the main rad return hose (I'm guessing) is about 30" to 40", or probabaly at least twice. Through the heater would be about the same.
• Radiators: Assuming the radiators have the same size core tubing inside and the same spacing (and the heat transfer efficiency per square inch to be the same), we could consider the number and length of the core tubes. For simplicity lets assume the man rad is 4 times the size of the auxilairy rad and both have two rows of tubes. The main rad's tubes would be twice as long, but there'd also be twice as many tubes. So, the resistance to flow might be considerd about the same.
• Conclusion: 
  • The water pump moves fluid through the engine but does not generate a significant pressure differential.
  • Fow rate is slow enough that resistance from velocity is negligible.
  • The size of the radiator (assuming same construction) does not significantly affect resistance.
  • The hoses (the portion of the circuits outside the engine) are the predominant source of resistance to flow, and the heater-size hoses would produce much more resistance.
  • The engine designers selected heater hose and rad sizes to suit the engine's main cooling system.

Thus, the only way an auxiliary cooling circuit could significantly reduce the effectiveness of the main rad cooling circuit would be if it was larger: a larger rad (or one with more tubes) and hoses of equal greater size.

Since you reaffirmed that your engine get hotter the faster you go, I'd suggest you look at the tuning of your engine in detail: if it is running too lean or with the spark timing incorrect it will run hotter the faster you go. Or, if you have a coolant flow restriction inside your block - rust buildup, sediment, a gasket incorectly installed, or a defective pump impeller... things like that.

I don't have a handy diagram, but as stated before, the water pump draws coolant from the heater return and the lower rad hose and pumps it into the engine. While you are correct that the coolant will take the line of least resistance, it is a closed system and the coolant is being pulled as well as being pushed.

I have run a second heater under the back seat, and the engine did not struggle to pump the coolant that distance with the thermostat open or closed. The heaters were in series.

I drove across Texas with an early four core rad, an oil cooler, a plastic fan and an Austin America heater core. The temp would drop to 160° F while at highway speeds and get warm in traffic, etc. this was in July of 1992.

If you can find Rob Fram's electric fan based cooling system description on here, Tin Box is his user name, read it. He has things figured out. A huge part of his system must be the air deflector that keeps hot air from the exhaust from being drawn through the rad. 

Your car does sound like a plastic fan being on backwards, as that causes lousy air flow at highway speeds but appears to work at lower speeds.

my own road trip mini has a super two core rad, large water pump pulley, 195° F thermostat and a great expansion tank. Note that an expansion tank is NOT an overflow bottle. This strong 998 pulls a 2.95 final drive at modern highway speeds all day long through the deserts of Southwest U.S. Without issue. The heater tap stays closed, the heater blows ambient air into the car, the engine runs a bit below 200° on intensely hot days, but will run cooler with the ignition splash shield removed, and cooler still with the grille removed, but I wouldn't want to look ghetto like that! It does have the restrictive Morris Cooper grille though.

As a kid, I had some lousy moments on road trips in minis and I learned the hard way. Would I ever sacrifice having a proper heater/demister/venting in a mini to make room for an aux rad again? No. Would I run oil through an oil cooler when it isn't needed? No. Am I thinking of buying a high performance Spal Fan from Amazon? Yes! That eleven inch one that draws forty amps seems to be the one to get. Will my next header get Jet Hot coating? Yes. Will I make a shield so that air can't travel from the header to be drawn through the rad? One of these days. 

My next mini road trip car will have AC, cruise, and a very happy 1380, and it will be as comfortable at -40°C as it will be at +40°C.

A few points of clarification:

1.  As my original posting said, my temps get hotter at highway speeds, high rpms.  This is why I was thinking that the the side mounted radiator was not benefitting from the extra airflow and reaching capacity, and so I wanted a front mounted auxiliary radiator which would benefit from the flow at speed and would also not need a fan on it.

2.  I agree with the statements that I should check and make sure everything else is functioning properly: timing, fan orientation, etc.  However, based on how well the car runs, and reading of heating problems for years from many folks, I suspect the car is not designed for Texas heat, so I want to improve it regardless of other issues.

3.  I agree with tmsmith when he says the thermostat has nothing to do with cooling once it opens completely (assuming it is opening completely at operating temp).  After that, the capacity of the other components are what determine the cooling capacity of the car.

4.  I respectfully disagree with the statement that pressure drops are not an issue in a water cooling system.  I didn't mean that the pressure drop & phase change transfers heat like in an AC system.  By pressure drop I meant the resistance to water flow through a device or channel.  Water flow is driven by pressure.  Water flows from higher pressure to lower pressure.  The water pump is what builds pressure to flow the water.  Now, if you had two parrallel channels, one with very low pressure drop (low resistance to flow), and one with very high pressure drop (high resistance to flow) most of your flow would go to the low resistance side.  So imagine I attach a very low resistance flow path in parrallel with my side mounted radiator or engine block.  Most flow would bypass the side radiator or engine and I would be making the cooling worse there.  This is what I want to avoid, and was wondering if anyone had a flow diagram that showed how the water flowed from water pump to engine, to heater core and radiator, and where the thermostat and temp sensor were located.  And ideally if anyone has made any measurements of the pressure drop across the radiator, engine block, and heater core of the existing design with the engine running at various rpms (doubting but wishfully thinking).  This information would help me decide on properly connecting the aux radiator and what kind of flow resistance would be acceptable.

5.  Finally, if you are commenting about how your car temp behaves under various conditions, please clarify if your factory radiator is mounted on the side, or in the front (like the newer cars) and it if is side-mounted do you have the shroud between the radiator and the inner fendor (mine does not).  If you are mounted on the front and telling me that you run cooler at speed, then I'll be less skeptical.