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MG MGA - Testing the cooling system

I hope all the members in Adelaide, a city in the state of South Australia, are out driving their MGA cars to test the cooling system. It is 43 degrees C (109 degrees F) and even hotter in country areas.

Mick
Mick Anderson

This was shot Christmas morn. I finally drove it Saturday morning. The high that day was 20 f or a balmy -7 c.
I am happy to report no trouble with the cooling system came right up to 190 and stayed put.


R J Brown

RJ, I dont believe that!! What stops the cover from collapsing with all that snow? It is a balmy 42c (108f) here in Melbourne at 5-15pm.
Barry
BM Gannon

Looks like I got out of Australia just in time! And I came back to the right part of the US, too! Low 70's and sunny today although it's been much colder recently.
Steve Simmons

Hi RJ lovely photo I assume you do have cover on and that the car hasn't filled up with snow lol


gordon
g c pugh

Barry, it's that Colorado Champagne Powder the skiers love. Light and fluffy.
R J Brown

I'll never complain about the cold spell we are having in Santa Barbara ever again.


David Holmes

I'll never complain about the cold spell we are having in Santa Barbara ever again.


David Holmes

Sorry, I hiccupped!
David Holmes

What's in the garage RJ? I presume it must be something more valuable than your A.
Andy Bounsall

Living in the northern Sierra foothills has it's advantages! Be nice, those are my baby daughters!
We drove my A to a party and back late last night, a spectacular clear, starry 34F. Heater full blast, dry country road, ancient warm color yellow lights, and my sweet wife next to me. It was indeed a Happy New Year!


Russ Carnes

We went for a spin today as the roads finally dried out and most of the gravel has been worn off of the pavement. Not too cold, only about 40 deg. F. I must do something about the door seals that do not really seal around the doors. Warm feet, cold leg on the door side. It causes a whining noise that comes from the passinger side of the car.


Ed Bell

Brought it home Christmas eve. Took my almost 15 year old daughter over to the high school parking lot to start teaching her how to operate a clutch. Buttoned up the cover and left it out to drive for Christmas. Foolish me I actually believed the weather guessers. Small chance of flurries clear by noon. HA! Rearranged the garage and fit it in instead of driving it Christmas day.
R J Brown

HI Ed try this link for clarke spares to my knowledge the only place that does the correct door seals as per original certainly made a big difference to mine, not cheap though



gordon
g c pugh

forgot link silly boy

http://www.clarkespares.com/doorseals.html
g c pugh

Hi every one. This is my first thread. Got my first MGA in September after 30 years of coveting, some of us are slower than others! Great to be part of this wonderful world-wide family now.
I noticed on a recent run, in 40 degrees, that the temperature was rising steadily (fair enough), then alarmingly. I turned off the freeway (only took it to get home quicker)and found that the temperature returned to cooler levels. I presumed that the faster wind speed would cool more efficiently, but I guess that there is an equilibrium between engine work rate and wind speed. On a hot day faster isn't necessarily better and a lower speed is better for cooling. Any thoughts?
Phillip Hughes

It would help if we knew a few other details. What was your constant speed on the freeway? Do you have a standard gearbox and 4.3 rear axle ratio?
It is easy to calculate your RPM, but do you remember what it was?
If it is a roadster, was the top up or down?

Once you get to a reasonably low speed the air cooling effect is as good as it is ever going to get. Even at low speeds the air passing through the radiator is in contact with it for a very small fraction of a second and at higher speeds even less time. The temperature difference between the air and the radiator is the important factor, not the amount of air.

At higher RPM the water pump is working faster and this can make a difference, but the water flow is limited by other factors.

The real problem is, as you have guessed, that the engine load, and hence the heat, builds up rapidly with speed. This is mainly due to air resistance and to a much lesser degree some friction factors.

Mick
Mick Anderson

I was able to take mine out a coule of times between Christmas and New Years once the snow and salt got washed away by the rain we had. Then New Years day we got dumped on. Oh well it's -14c(+2f) today so it's back inside till spring I guess.
Happy New Year

Kris


Kris Sorensen

We are promised some snow today/tomorrow, so will be leaving car out of garage overnight to get the seasonal look!! - some hope. Rarely get snow here on the Fylde coast. Very few locals seem to know how to handle cars in slippery conditions. Good spectator sport unless you are on the receiving end of an imminent collision.

Oz certainly seems a bit hot at the moment. Looks like an imminent national drought disaster.

Went up to our Lake District last weekend. Flooded roads up to axle height everywhere. Bet we have hosepipe bans within the next few months.

Steve
Steve Gyles

Phillip, Welcome to the forum.
I have often heard MG owners comment on a hot day - 'we love to drive our little cars -- for a short distance'!!
40C is probably marginal and if you are in heavy traffic then you need to keep moving and maintain a long gap from the car in front. Any prolonged stopping will send the needle over the top.
I have fitted an electric fan as well as the original, cleaned the radiator yet again, fitted the coolest thermostat available and try to avoid stop start traffic. So far this summer all has gone well. Perhaps we could do with some of Steve's Lake District weather!
Barry
BM Gannon

Phillip,

If keeping your engine cool is a problem, following are 10 items to consider:

1) Be sure there is sufficient coolant.
a) Check that the radiator is filled with liquid. (Duh!) Install an overflow bottle to monitor loss and prevent spills.
b) Don't use an antifreeze mixture with more than 50% glycol. (Less obvious.)
Water has much better heat transfer (thermal conductivity) characteristics. (Like many people, over the years I fell victim to the marketing strategy that re-labeled glycol from "anti-freeze" to "coolant." I had gradually increased the percentage to 2/3 glycol and 1/3 water to generate the largest range between freezing point and boiling point. The reality is that water is the far superior coolant. The addition of glycol provides protection by lowering the freezing point and raising the boiling point.) Too much glycol causes the thermal conductivity to fall faster than the boiling point is raised with the result that the solution boils, which is not good.

Radiators on modern cars are much more efficient than the original style used in the MGA, so the coolant mixture in a modern car is not as critical in transferring the heat from the engine to the radiator.

2) Ensure the water pump is working.
The fan belt should be properly tensioned. While running, the pump should not be leaking or whining. There should be signs of flow visible in the radiator (cap removed) once the thermostat is open. (Of course, ONLY remove the cap when the engine and radiator are cool! And, if the engine is running, MIND the FAN!)
Note, a higher flow rate through the radiator does NOT intrinsically result in reducing the net heat dissipation. Less heat is dissipated per pass, but more passes are made per unit time. So long as the speed of the water pump is not fast enough to induce cavitation, a faster flow provides improved cooling.

3) Check that the radiator is not restricted by corrosion or design.
There has been discussion that some vintage of aftermarket radiators did not have sufficient flow or heat dissipation. (I have a c. 1990 vintage radiator obtained from Moss - I believe it was made in China or India. It provided about the same cooling ability as the old, original, partially clogged radiator, but the replacement didn't leak.) One measure of the radiator's resistance to flow is to fill it with water and time how quickly it drains.

4) Ensure that the distributor and carburetors are working properly.
Check that the ignition timing is correct. Note that the springs controlling the mechanical advance and the diaphragm controlling the vacuum advance both degrade with age. Consequently, while the static timing may be correct, at higher rpm the advance may not sufficient. Similarly, the carburetor needles may be worn and so a setup that is correct near idle may be too lean at speed. Finally, be sure the gasoline is fresh and of sufficient octane. (Try Sunoco's street-legal 100 octane racing fuel at least once – it's expensive, but if nothing else it stays fresh longer.)

5) Ensure that the air entering the grill isn't bypassing the radiator
a) Install the original style felt on the inner side of the bonnet above radiator.
b) Be sure the carburetor and interior air hoses are installed.

6) Ensure that air flow isn't restricted by an aftermarket grill.
There has been discussion that some vintage of aftermarket grills had the slats oriented at too shallow an angle, which reduced airflow to the radiator. The effect of the grill can be evaluated by removing it. Cars prepared for racing often remove every other slat, as had been done for the original factory racers.

7) Ensure the correct thermostat is installed and working properly.
Also consider installing the bellows type thermostat that blanks off the bypass port in the head once the operating temperature is reached - although only the earlier A's used this type of thermostat.

8) Ensure the proper radiator cap is installed.
This is mainly for protection against overheating.
(Note, the bellows-type thermostat runs at a lower pressure to ensure the bellows isn't crushed. The later model thermostat can be run at the higher pressure.)

The following items go beyond the original equipment configuration:

9) Use a whetting agent in the coolant.

10) Increase air flow through the radiator
a) Install a shroud for the radiator fan.
This can improve cooling at low speed.
b) Install an electric fan.
This can further improve cooling at low speed and help ensure flow at high speed, but should not be necessary for street use in temperate climates.

Steve

Steve K

Phillip,

As the Australian built MGA did not normally have a heater, do you have the blanking disc fitted to the hole to the right side of the radiator (facing forward in direction of travel)?
In the Service Parts List this disc is part number AHH5396. It is on the same page as the radiator blind.


Mick
Mick Anderson

Steve K, thankyou, that is a great list. I think I am pretty clear on all those points. Mick, still looking for that blanking disc.
I am just amazed at the depth of knowledge shown by members of this BBS. I am sure that many of you will forget more than I will ever know!
Steve's list brings me to my second query. I have to pour a lot of water into the radiator every time I use it. Is this normal? I suspect I could be over filling it and it is blowing off. However, I fill it only so I can just see it below the cap, ie. below the overflow hose. Forget american express, I never leave home without my spare water bottle. Am I alone?
Phillip Hughes

Mick.
Thanks, I leaned something new today. And it's only 7:49 AM!. I never heard of the blanking plate. But sure enough, there it is in black and white on the parts list. It is funny that it is not listed as "Optional" or "Alternative" but the description is listed under "Sundries" whch I assume is options.

A question. If a car is devoid of a heater, what was done with the slots in the scuttle that were for the defroster?

I have just looked in "Original MGA" with a new eye for this and see a BRG twin cam on pg 49 that has no heater controls but still has the defroster chrome. Were these just for show? or were they actually fed some air from somewhaere else?

Chuck
C Schaefer

Chuck, just for show!

Neil
Neil McGurk

Phillip,

If you fill the radiator to just below the overflow when cool, then it's likely that some fluid will be expelled when it's hot. How much are you losing? The system holds just about 4 quarts when full, so if you're losing more than a pint you may have a leak of some kind. By the sounds of how hot it is by you, you may wish to consider running just water and no glycol - especially until you sort out where the coolant is going. (Again, consider installing an aftermarket overflow bottle, at least until you resolve the loss, especially if you are using any glycol, as it's deadly toxic and animals are attracted to it because of its sweetness.)

Are you leaving any puddles of coolant under the car at idle or after running? Any signs of leaking from various parts of the radiator itself? Anything dripping from the water pump weep hole? Any coolant spray/mist residue in the engine compartment? Any signs of leaks around the head gasket? Any signs of vapor coming out the exhaust? Do you have a good radiator cap? Any chance you're boiling it off?

Steve
Steve K

Phillip, I have fitted an overflow tank, from an Austin 1800, which the fluid is pushed into when it gets hot, and is drawn from as it cools. It works. Steve K is right, save some cash, don't use the coolant until you seal the system. I can arrange to borrow a radiator pump to help find leaks if needed.
Good luck, Barry
BM Gannon

Neil, Thanks. Being in northern Ilinois, few cars here are without heaters so I have no point of reference. I guess having the openings cut in the scuttle make sense. That way a heater could be added if required by the dealer.

Anybody have a photo of the blanking plate? Is it just a circular with three tabs bent or spotwelded?
Chuck
C Schaefer

Chuck, The original is made from a laminated fibre board material. I made one recently, for a concour car, from a stiff cardboard and painted it rather liberally to waterproof it. It is held in place with three steel spring clips. I think Todd Clarke makes them.
Barry
BM Gannon

Guys,
Welcome Phillip - another Victorian. The blanking plate that takes the place of the Smiths heater is rectangular, steel plate with a stepped flange around the perimter, fixed with #10-32 3/4" screws - Kilmartin Sheet Metal here is Victoria make them - about $20.
Regards
Mike
Mike Ellsmore

Hi Mike,

The blanking item being discussed is not the rectangular one which replaces the heater unit if it is not fitted.
It is the circular blanking disc that fits in the hole to the right of the radiator mounting when a heater is not fitted.

Mick
Mick Anderson

Barry,

Thanks, Although I do not have the need for one because I run a heater, I try to capture any errant bits of info about the A and store them away in the dark spaces of my mind. Would still be nice to have a photo of an original if somebody has one.

As an aside, for awhile I was trying to work out some cooling issues on a coupe I had. I stuffed a wad of newspaper in the opposite side tube( the one feeding fresh air to the carbs) to force the fresh air thru the radiator. I guess this blanking plate is the factory equivalent. I now wonder if the factory used newspaper as a prototype:>)

Chuck
C Schaefer

This thread was discussed between 31/12/2007 and 05/01/2008

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