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Auxiliary Radiator

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77_MG_Midget

77_MG_Midget

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I've read about midget owners putting an auxiliary radiator (usually just a gm heater core) to assist in keeping the engine cool. Well, my PO had done just this. It is (was as I pulled the engine this weekend), located behind the grill and in front of the radiator.

My question is, he ran the lines for the aux. radiator between the heater core and the water choke on the carb /ubbthreads/images/graemlins/confused.gif. As the water choke hose is quite a bit smaller than the heater core, I'd think this restriction would reduce a lot of the cooling capacity of the aux. radiator.

Has anyone else done this conversion and if so, what is the best way to plumb the aux. heater. I'm thinking of keeping it just because it gets so hot here in the desert during the summer.
 
In my opinion, auxiliary radiators are a poor substitute for a "good" radiator core. Also your old core may be restricted by junk that cannot really be economically removed. Your core can be replaced with a much more efficient design that fits in nearly the same space as your old one. After fooling around with add on stuff, you may find that it cost nearly as much as a recore & doesn't work as well. Radiator shops do this sort of modification every day.
D
 
I'm with Dave on this one. If your car overheats, even in desert temperatures, there's probably something wrong with your cooling system.

If the engine is in perfect tune, I'd start diagnosing the overheating with the radiator. Often, a good recore will do the trick. If it's the original radiator, you can almost bet it needs a recore. And sometimes if the engine has not been carefully overhauled, your water passages may have calcification or scaling that retards coolant flow. Also check the water pump.

But, in a street (not racing) car, I'd never consider an extra radiator.

My tuppence worth, I hope it's helpful!

Good luck, let us know.
 
Spridgets are obviously different than Minis, but the A- and A+ series (particularly large bore) engines in Minis have always had temperature problems when operated in warmer climates than the U.K. BMC/BL/Rover recognized this and created a whole series of different fan types to address this. They also changed the radiator core design as mentioned above. If you were shopping for a Mini radiator today you're faced with three different types/styles which you have to select based on available space, budget, and fan type.

Perhaps Spridgets don't have the same number of options that Minis do... but they run the same series of engines which will likely have the same temperature problems. I've always thought the auxiliary radiator looks awful... but it does work both by increasing the system capacity and the surface area for cooling.
 
Hi John,
If you decide to get the radiator re-cored, there are a number of improvements available in core design. More tubes in the same space, more fins in the same space, different fin types, better materials. You can frequently get 70% more cooling capacity in the same space as the original. TransPro is one of the better core suppliers. They will often supply a custom core to your specs & size in a few days. Most local radiator shops have a connection to TransPro & can advise you on what will be best & will fit your car. They will order the core & install it in your tanks/brackets.
D
 
Thanks to everyone that replied to this post. I agree, the aux radiator doesn't look all that good. I had planned on having the original radiator re-cored as I am in the process of refreshing the engine.

I'll check around locally on having more cores/different fins put in.

That's what I like about this board... so many knowledgable people!!! Thanks again!!!
 
If you want additional cooling, why not consider an oil cooler? It looks good and does aid in cooling the engine.
As a side point, it tends to help the bottom end of the engine.
 
This my be a little off topic, but if you add an oil cooler do you have to run more oil to make up for what is in the cooler lines and the cooler itself?
 
Yes, but it usually doesn't drain out when you change the oil ... My car (a 1500) takes about 5 qts (actually roughly 4.5), but the 1 qt or so in the oil cooler doesn't go out. Since I change the oil quite frequently because I autocross it, it isn't really a problem, but I'd recommend frequent oil changes if you have a fresh engine (but then again I'm a little hypersensitive). I used to change the oil 500-1000 miles, but now I change it every few months (which amounts to a few autocrosses or about 50 miles). I know it's a lot, but oil is cheap when compared to rebuilt engines ... and I haven't had occasion to drive on the street in a long while, or it'd go further between changes.
 
[ QUOTE ]
If you want additional cooling, why not consider an oil cooler? It looks good and does aid in cooling the engine.

[/ QUOTE ]
An oil cooler that does not have a thermostatic bypass creates a few problems. The oil MUST get above 200 degrees F. to evaporate the moisture that collects in it as a natural result of combustion byproducts. Water, combined with the sulphur byproducts can make sulfuric acid which is hard on bearings. Ideally the oil should run at 210 plus degrees. If you add a cooler, be sure that it has a thermostatic control.

An oil cooler provides no where near the improvement that a "good" radiator core does.
D
 
All, good thread, makes me think of adding an oiltemp gage. are ther any? must be. Here's one. So if oil must reach 200, how high is too high? i would guess by looking at this gage that 250 is upper end? I spoke once with a gent from one of the supply companies at work and he basicaly said the same as Dave. It needs to get to temp, thats why short drives are hard on an engine.

why dont more cars have oil temp gages?

mark
 
I don't currently have a thermostat on my oil cooler, but am looking for one. My oil cooler adapter is of the sandwich type and the threads are BSF. Where could I find a thermostat which would not require two additional hoses (for a total of 4). The fittings were outrageous at like $35 each, so unless I find a better source, I'd rather avoid paying that much for fittings and rather keep my engine bay less cluttered. I haven't had time to pursue this as of yet, but I would like to know if anyone has any sources.

Matt
 
Hi Matt,
There are sandwich type cooler adapter plates with built in thermostats available. I have used one on a Mustang. I realize this won't fit your engine. You may have to do some research.
D
 
I am researching oil coolers right now for my 77 midget. I found that this site https://www.batinc.net/main.htm has a lot to offer, though I am still trying to find out if the prices are competitive. They are a US partner of https://www.thinkauto.com/index.htm. My cousin has a Mocal setup and is very happy with it. I think the one for the 1500 is the SP1A which is available with and without the thermostatic feature.

**I agree with the comments above, however, that an oil cooler is should not be installed in lieu of rectifying any issues with the collant system. Clean cooling and oil systems, working in conjunction, will be very nice, but an oil cooler will not take up all the slack of a blocked up radiator.
 
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