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MG MGA - MGA additional cooling fan

Although (apart from a jammed master brake cylinder under repair) my MKII 1622 is running superbly right now, after a reasonably long journey when stuck in traffic in warm to hot weather it overheats.
My idea is to find and fit a second cooling fan in front of the radiator, seperately switcheable for these occasions.

Unless someone knows of a problem I have not found that could cause this? I am guessing it is fairly normal?

Thoughts, tips and ideas welcome!
If nothing else a suggestion for where to look to find a suitbale fan please?


Allan Wakefield
A M Wakefield

I will send a couple of photos of my installation. My fan is connected to the unused F switch on the dash. The fan works very well for slow going on hot days. Mine is an 12" diameter, 10 blade fan that I purchased many years ago from an automotive parts discount store. It moves an amazing amount of air. I performed a check to see if the fan in front of the radiator caused overheating and it seemed to have no effect when not used. Hope this helps, let me know if you need anything else and have a good day!


John Progess

Here is another view.


John Progess

I see you are running an oil cooler as well, as a fan. Hard to believe there is no coooling problem with all of that "blockage" in front of the radiator. By any chance do you have an overflow bottle on your rad? I run hot when warm weather and slow movement prevents air from circulating thru the rad and have considered an extra fan. Coulsd use all the "expert" help I can get. Gordon
Gordon Harrison

Over heating is usually a number of small improvements that get you to the point of success.
Small things like:
Is the fan on the right direction? Coolant 70% water 30% coolant (pure antifreeze conducts heat poorly). Water wetter(makes water conduct heat better). Seal on top of radiator to force all air through the radiator. Heater air tubes in place. Plugging the 4" air tube hole on carb side. Was you block "hot tanked" to remove all scale from inside? Proper thermostat (sleeved style). Good seal at radiator cap. Is your radiator 100% clean in and out. Is your temp gauge accurate? it is easy to verify the accuracy of the temp gauge by placing the sensor bulb in boiling water (a known constant, adjusted for altitude).
On my stock cars (4 so far) I was always able to get proper cooling without an auxiliary fan. That said I would not hesitate to use one if I felt it would help. I have a Mazda RX 7 engine in an MGA. For it I needed a oil cooler under the radiator shelf getting air through a hole in the valance. I used 2 fans,1 front right and the other back left on the radiator (no belt turned fan). The radiator was also re cored with a thicker core. Fans are hooked to fog light switch but NOT powered from the red light wires. Fused supply wire grounded through switch and red-yellow wire.
R J Brown

Allen, I have a 1622 in mine and use a raidiator shroud that I got from Moss as well as an oil cooler in front of the radiator. My temp maxes out at 200 in stop and go traffic and stays at 185df while moving. R J Brown is correct that all of the system needs to be in good working order for the engine to cool properly. With the shroud attached I have had no problems and I live where the afternoon temps reach 95-105df. Try the shroud it certainly made a difference to mine. Hope this helps....Norm
J Dick

What is this shroud?
Thanks to all for the input, I will look at tweaking solutions before an additional fan then, maybe both :)
I have the oil cooler already fitted.
A M Wakefield


You forgot to send me a mail to remind me to put the Eezibleed in the car for you for tomorrow. I have remembered!

Check you have a corect radiator cap. Check that your points are set correctly - if the cam has worn, your timing will be too far advanced and will cause overheating. Check mixture is not too lean (have you serviced the car since we tuned it last year?)

The shrouds sare for the timid (and reports are very mixed). If you want the cool factor (in every sense) go for a real man's solution and fit a SC.

If you want a thermostatically switched fan, these are available, and I can give you a source for a used one. The neatest way to fit the thermstat is with a special top hose.

see you on Friday morning (make it before 10.00!)

dominic clancy

If I could find a Judson SC I would fit one :)

Anyhow, thanks for all the advice, more work gone onto the 'to do' list.
Right off to dodge the glorious summer weather and hide under the MGA in the garage :(
The things we do for love !
A M Wakefield

I have installed a Moss fan shroud and love it. It completely removed the quick heat changes we were getting during stop start traffic and steep hill climb situations. I have included an image. This would have to be better than an electric auxillary fan as it requires no power, servicing, is light weight, stops any air re-entering the radiator and will work forever. And doent look out of place in the engine bay as you hardly see it.

DJ Lake

To shroud users: is there still clearance at the bottom of the radiator for the hand crank?
Marvin Stuart

To Marvin: Yes.
Andy Bounsall

I have done all the things mentioned plus a few to try and solve the heating problem. I have installed an overflow bottle but have not tried it yet. My engine is a 5 main 1800 and it runs 190 deg on a 100 deg outside temp day. I rarely use the fan, only is slow traffic on hot days. Have a good day!

John Progess

One thing I don't think anyone has mentioned. Have the radiator recored using a modern optimal core AND have the filler neck replaced so that you can fit a modern cap instead of the 7 lb. stock item.

Modern cars run to 230 deg. all the time with no problems at all. You just have to get used to the needle being in the top half of the gauge. With a suitable cap and a core that won't leak, it is no problem at all.
Bill Spohn

I had over heating problems when I fitted 1800 5 Bearing engine and the Moss supercharger but it always run hot before. Probably because some dick head powdercoated the core as well as the rad top so I sent it to my local Rad specialist who put in a modern core This was even worse and costly. My soloution was suggested by bob West. I sent him the rad to be recored again with a special large capacity core and changed the thermostat to a 74' one and closed all the gaps around the rad and bonnet. now the electric fan that is thermostaticly controled dos'nt even come on. it now runs at 170 on the gauge.which I thought was a bit cool so I tried a 84' thermo and then experiance running on when I switched the ignition off so I went back to the 74'its now fine. Hope this helps. dont use a modern core unlees it a high capacity one.


David swaine

With 50/50 mix of a-freeze/water and 7 psi pressure cap the boiling point is 250+dF, so you can run the temperature gauge past 230dF, up to about 85psi in the oil pressure range (where it finally runs out of mechanical travel) without boiling. As such, there is no reason to use a higher pressure cap (unless you might also install a higher range temperature gauge). I have run in this condition (well beyond 230dF) on numerous occasions with 7 psi pressure cap with no problems (except vapor lock issues at low speed). See here:
Barney Gaylord

I agree with Barney. Also, if you have a high efficiency core (there should be about 40 tubes across the front of the radiator and 3 deep, about 120 tubes total) you should not have any problems unless you have a head gasket leak or rust in the block or something. A fan in front of the radiator will help at slow speeds only and will block air at high speed. (I have a lot of experience with MG's in Los Angeles freeway traffic for 28+ years).
M. H. Dabney

Another option is to purchase a non stock radiator ( I know the purests will hate me) but i've experienced the same heat issue with my street and vintage racer. Ron Davis makes an aluminum raidator that works so well, that I have to tape off a portion of the rad to get enough temp into the motor. Hi temps are very common in our cars and can quickly damage a motor. A good electric fan is a nice option as well. See below.

My 2 centavos.

k brown

This thread was discussed between 08/05/2008 and 13/05/2008

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