MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Keeping engine cool

Hi
I took my 1600Mk2 out today for its first proper run this year. Ran like a dream but at times the temperature guage got pretty high.
I must admit with embarassment, that I discovered afterwards that it took a litre and a half water. I think (hope) it was not leaking but low from the start as I had drained it some months ago, and there was probably some air locks when I filled it.

Most of the time the temperature was OK but interestingly as well as the normal problem in traffic, I noticed when I was on the motorway doing a constant 60mph, the temperature went up.

I realise the lack of water didn't help, but was wondering if there is a heat problem at speed because I do not have that piece of felt on the bonnet above the radiator. Just wondering if at speed, as the exit routes from under the bonnet are not that great, whether the air just recirculates over the radiator and so the fan is sucking in hot air rather than cool stuff?
Be interested to hear what you think, Graham
g Victors

Pretty hard to judge if you were low on coolant to begin with.....
Assuming that your cooling system was properly maintained, and your water pump is working as it should,
slight changes in temperature , going up and down hills, is normal....
My thermostat is 165 degree F., and my temp gauge usually stays at about 90 degrees C....
I have an electric fan, and a "B" 7- blade fan, with the Moss fan shroud....
Another suggestion is twisting the grille bars so they are more toward the front.
Edward
E B Wesson

1.5 litres is about the normal loss of coolant from expansion when engine temp reaches 200F. I would be looking at all the ways to lower operating temp as discussed on this site many times. Search archives and read mgaguru re cooling.
Mike
Mike Ellsmore

Thermal expansion is about a pint or half liter.
Barney Gaylord

Hi
Yes I have read loads on the archives but couldn't find any discussion on the "bonnet felt".
My normal running temperature is about 195 but it went well above the 212 mark. It was a very hot day

g Victors

I was out driving in similar conditions yesterday and earlier in the week (about 28 - 30 ambient) and my gauge never went above 175 - 180. In my opinion you have some serious airflow/cooling issues. Perhaps you could tell us a bit more detail about your system. For example, what radiator you are using; original or a modern re-core layout - my pet theme as all on this BBS will tell you.

As an aside, I have seen MGAs with any number of car badges bolted to the grill. I often wonder what their cooling is like?

Steve
Steve Gyles

Graham, you also need to check the cap and make sure it is the long reach type. I ran for a couple of years with a shorter cap without realising it. Found it after one day in hot standstill traffic coolant was boiling out of the overflow.

Never had any problem over the years since and I don't have the bonnet felt (yet).
Neil MG

I went out for a twenty mile run last week when it was around 26 deg C here and I only just made it back due to overheating. On return the front body shroud next to the grille was too hot to touch!

I do have a felt bonnet seal but also had my radiator recored by a local shop during the restoration. My favourite cause of the problem is the radiator but it's an expensive solution to change it so I've been looking first at my next favourite which is the radiator grille.
Looking at the total grille gap from the direction of air flow the open area on mine is only 50 sq. inches whereas the area of the radiator itself is 200 sq. inches. Without the grille slats in place the open area is around 150 sq.inches so the grille is clearly a big obstruction.

The gaps between my repro. grille slats were 1/4" wide and its quite easy to twist them at top and bottom to get them 3/8" without it affecting the front appearance too much. I'm sure that 95% of people wouldn't notice any difference. It's only a ten minute job using a pair of pliers with tape wrapped around the ends. This will increase the open grille area by 50% but whether 75 sq. inches will be enough I'm doubtful. At least it should be going in the right direction.

Strictly speaking I really need to wait for another 26 deg day, doing the same run to see what difference it makes. The past few days have only been 23 deg! ..........................Mike
m.j. moore

Graham
We are 3/4 of the way across our Pyrenean traverse from the med to the Atlantic and we have experienced some pretty high temperatures on the way. (Mid 30s)
have experimented with fitting my car with twin electric fans and I have risked removing the engine driven fan to see if it would cope.
When I first tried it in the uk the car seemed to run about 10 degrees hotter at 185 degrees than it used to. I then opened up the vanes of my repro grille and this brought the running temp down to 175 which is the temp it used to run with the NTG engine driven plastic fan I had on before.
On really hot days (35 degrees plus) the temp has reached 195 degrees F on long climbs up the mountain passes and on 70mph plus runs but has always come down again when descending.
I am trying to adjust the stat so that it only switches on when the car Is either stationary or in slow traffic.
It is working well so far and keeping the car cool but I did bring the plastic fan wlth me just in case the electric fans didn't cope.

I think I can safely leave it behind in future.
Will update you all when we get back next week.
Colyn





.
c firth

Thanks for all the feedback.

I know that Steve has runs the coolest MGA in town!

Neil, my radiator cap has an internal length of about 1 inch (approx), and when I screw it on I can feel the spring compressing, so pretty sure it has a long enough neck. It has a number "4" on it, which I assumes is 4lbs - but according to Barney's pages, the 1622 engine should be 7lbs. I realise if I switch to a "7" that will increase the boiling point, but will it have any effect on actual temperature? Is it worth swapping?

Mike, I have a Mk2 (so different grill to most) and cant see it can be easily adjusted.

Colyn, You are certainly testing your cooling system! I have often thought about fitting an electric fan, but I had thought its real benefit is at low speeds rather than high loads? Enjoy your trip

Graham
g Victors

Graham
I personally do not think that 4 lbs is enough....You have to be loosing fluid at that pressure...(I know it's hard to tell)....
Go to the correct length 7 lb cap, before you do anything else.
Edward
E B Wesson

By and large we all have the same or similar configurations under the MGA bonnet, so I am always bemused that in similar environmental conditions (UK in this thread) we can have such a variation in running temperatures. What are the most obvious things that change under the bonnet over a period of time that could have an impact? Assuming all cars came out the factory the same, the list, in my opinion, is quite small if we disregard deliberate modification factors such as bending slats:

1. Silting up of the engine/radiator.
2. Wrong radiator cap.
3. Replacement radiator.
4. Malfunctioning thermostat.

Over the years I have become convinced that the radiator is the prime suspect. My reasoning is not without foundation. I have an original spec radiator. My 1500 engine never had an overheating issue. When I changed to an 1800 it was identical; no overheating. Meanwhile my near neighbour had a 1600 that ran hot just like Graham's. He tried everything, including flushing through, different themostats, fitting an electric fan, bending the slats etc, all to no avail. Then one day, while I had my 1800 out for a repaint I lent him my radiator. Instant success. So off he went to Bob West for an exchange radiator and has not had a problem since.

The MGA radiator core was designed into the car. Most modern core designs do not work in our cars.

Steve
Steve Gyles

I agree 100% Steve.
Neil MG

Ditto, ditto, ditto. Original cell core radiator is good stuff, always run cool. Modern VT (Vertical Tube) cores are pretty lame by comparison.
Barney Gaylord

One of the things that I have discovered in my quest for
"cool", has been the difference in the heat coefficients,
between copper and aluminum.....
The modern core replacements are frequently made of aluminum, with plastic tanks, while the old radiators were copper, with metal tanks....Copper has a much greater ability to dissipate heat than aluminum, which is why aluminum radiators are almost always multi-cored, to make up the difference....But they don't work nearly as well as the original radiators....
I don't know if this is the problem here, but my vote is always to go back to an "old-style" radiator.
Edward
E B Wesson

Interesting reading. Any idea how I can tell if my rad is original MGA type or not?
Graham
g Victors

http://mgaguru.com/mgtech/cooling/cool_100.htm
http://mgaguru.com/mgtech/cooling/cool_100a.htm
Barney Gaylord

What is the correct thermostat to use?
Nigel Munford

I have just read Barney's notes for the first time that he has linked above. I zeroed in on the comment about a none standard core: "......but I did note that the faster I drove the higher the temperature went - a sure sign that not enough air was getting through the radiator. "

There you are Graham, somewhere along the line your car has been fitted with a repro radiator with a non standard core. I am not sure which suppliers, other than the one Bob West uses, still do the 'original' (or similar spec) cores. Give Bob a ring and see what he advises you.

If there are other suitable core suppliers in the UK it may be worth making a list here for our benefit in future.

Steve
Steve Gyles

Yes that's the point - what is it about the normal present day cores that make them worse for the car? Are they more resistive to water flow (smaller diameter tubes) and require a better water pump with more force? I could believe that over the years water pumps in general have improved and that radiator core design has changed to take advantage.

When I took my radiator for a new core years ago I wasn't given a choice on core design; I don't recall them even asking for what car it was intended.

Assuming my radiator core is not up to scratch what would I ask for if I got a replacement. Has anyone disected an original core? Does anyone know how the Bob West cores are constructed? Any measurements?

Yesterday I tried to see if opening my grille slats had made any difference so I removed the radiator cap and stuck a thermometer in the water and idled the engine at about 600 rpm until the temperature stabilized. The thermostat opened at about 77 deg C but the radiator coolant temperature kept climbing to around 92 deg C; the Jaeger gauge read 206 deg F (97 C) and the ambient temperature was only 20 deg C.

I then blanked off the right hand half of the grille and it made no noticeable difference to coolant temperature. To me then it looks like bending the slats is not really worth doing if your problem is when the car is stationary................................Mike
m.j. moore

Steve - Yes that sounds like me. I am not sure I can justify the cost of a different rad bearing in mind it was (very sadly) only my first outing this year, and of course we dont normally experience so much warm weather.
I think I can live with the temp increases at speed, but on a hot day, I always get nervous in traffic. So I am thinking an electric fan would be a more sensible investment for me? I assume Kenlowe is the way to go. Do most people remove the belt driven fan for extra mpg etc?
Graham
g Victors

Graham

You are talking about going the route of so many others: treating the symptoms, not the cause. You will end up spending money and time on needless modifications instead of biting the bullet and sorting the source of the problem once and for all.

Steve
Steve Gyles

I have been resisting changing my radiator for some time as it is an early re-core, i.e. not modern, so is probably better than modern ones. Looking at Barney's pages, and now having an 1800 engine, I realise though that although my radiator is early 70s or earlier it is not re-cored as an original A radiator.

I am taking Steve' advice and spoke to Bob West yesterday. I decided that I can see this season out on the current set up with suitable tlc but come late October my radiator will be off to Bob for a re-core.

Does anyone know how aluminium radiators can be sold as an improvement considering aluminium's poorer thermal copper compared to copper? I realise that they do have a weight advantage hence cooling per pound weight is probably better, but cooling per cubic inch of radiator will surely be poorer and that is what we care about under an A bonnet.

Paul
Paul Dean

Although I can't be certain, I think my car has an original radiator. It has the Morris Motors badge and the core looks like the one on Barney's site. The top tank, under the paint, looked at first like steel but will not attract a magnet so I suspect it is brass tinned in a solder bath. The brackets and fan guard are steel.

The car does overheat in standing traffic but is fine when moving. I can see no light through the air passages when putting a lamp behind but on idle there is a good suction on the radiator front face easily holding a piece of card in place so they are not completely blocked but I guess are now partly obstructed with 50 plus years of dead flies etc.

I suspect that my overheating problem is caused by partially blocked water ways and not helped by the repro grille. I have tried a couple of the standard liquid additives that "clean" out radiators and in my opinion/experience they are a complete waste of time. I have not risked the more robust treatments.

Its probably time for a new radiator.

Malcolm Asquith

Malcolm, I tried the 'card' test on mine during idling the other day - actually I used a core sized piece of paper and like you I found the suction to hold it in place was good but only in the area corresponding to the fan area. Beyond the fan area there was no suction, in fact air was actually blowing in the opposite direction from the engine compartment towards the front of the car witnessed by the edge of the paper pushed outwards and fluttering.

This would suggest that the air pressure in the engine compartment is quite high or that the tip of the fan is actually causing air to be pushed back through. I don't think this is good news because this air will be again sucked through the core and get even hotter and so on. Maybe this is why fan shrouds can be effective.

When you say yours overheats on idling do you mean that your temperature also gets to over 200 F similar to mine?
My radiator core however is effectively brand new so it's unlikely mine is partially clogged. Maybe this behaviour is quite normal during idling in summer temperatures. Like yours when moving I have no problem. The trouble I have is that when the temperature gets to 205-210 the engine starts to falter and is clearly unhappy. I've put this down to vapourization but maybe it's something else...........................Mike
m.j. moore

I've just tried the paper test again and in the extreme corners of the radiator the paper blows back. The area affected is about two inches from the corner so the area "sucked" is quite a bit larger than the fan. I also noticed that the core is a slightly different colour (cleaner) in the reverse flow areas presumably because the radiator is not having dirt drawn in.

At idle on a hot day the temp will reach 200F and then problems with fuel vapourisation set in. I don't have a fan shroud or a bilge blower. The fan is standard. I do have an oil cooler with thermostat - not sure why, just seemed like a good idea at the time.

Serious overheating happens relatively rarely and the engine has never boiled. I have lived with it for years but I think the problem is getting worse so this winter could be time for a swap.

Are Bob West's radiators a rebuild, exchange or an outright purchase?

Malcolm
Malcolm Asquith

Steve..re your comment below about treating the symptoms and not the cause. This is not a disease... it is a cooling problem ..and there are a few factors involved incl....radiator efficiency/heat transfer capability, fan coverage ,airspeed , road speed, hot air recycling etc etc.
I am not a purist re the MGA and have made many mods ( as I recollect you have ) and many of the mods have been directed to getting more umph to the wheels ( ie reducing inefficiencies ). The mechanical fan is one such..it has weight and therefore rotational inertia, it flies around at engine speed pumping air at quantities unrelated to need allowing a wide range of coolant temps. and has poor radiator area coverage..in other words the standard original mga cooling set up is an inefficient product of its time. I do not see that electric fans ( I have had a twin set up for years ..it is great ..even here in Oz ) are treating symptoms. They are improving on antiquity and giving more horses and economy .I would suggest they can cure the problem irrespective of the radiator configuration or material . By all means change the material and core configuration but the fan looks like it was designed by Isambard K B..( my favourite Victoran ) ..and unless you are a purist it should go ( or be kept in the boot with the elastic band if you are a nervous Nellie.)
Neil Ferguson

Its true that aluminium has about half the conductivity of copper, but both are streets ahead of other metals such as stainless steel. I do not think that the wall conductivity of the tubes is a significant factor. Resistance to heat transfer is greatest in the air film outside the tube, hands down. So, factors are overall fin area and air flowrate through the rad opening.
Art Pearse

Art..I agree totally...... basic heat transfer coefficients show this ...
Neil Ferguson

Malcolm

Bob West's radiators are a re-core of your own radiator hence this is why I am waiting until I take the car off the road for the winter, and my problem isn't that bad.

Paul
Paul Dean

The Moss fan shroud is meant to take care of the lack of corner cooling on the "A" radiator....It is primarily meant to reduce heat due to slow or traffic conditions....
As I mentioned earlier, I have this shroud, and it does work as intended....I would buy it again, if needed. I also think the "B" fan is more efficient than the original...It is lighter, and has more air movement.
Finally, I have installed an electric fan, that kicks on at about 92 degrees C., and it brings the temp down almost immediately.
For me, anything that can be done to keep the engine in the thermostat range, is a good thing.
Edward


E B Wesson

I have to disagree with assertions that the MGA cooling system is not up to scratch. Mine is completely standard with 82C thermostat normal radiator and cooling fan. I have never fitted the felt strip above the radiator. The gauge comes onto 100C in boiling water. Engine temp on an average day is 75C. The system is all working fine (I know this because the fan belt disintegrated a few weeks ago and the car DID overheat).

Even with a supercharger, charging up mountains on hot days (28-32C) does not lead to overheating. Fitting the supercharger dropped engine temps by 10C! And I have to use a radiator blind in winter to eliminate overcooling problems.

I suspect the main reasons that people have cooling problems are:

1. Fitting denser cores into the radiator that impede airflow and actually make the system performance worse.

2. Never having cleaned out 50 years worn of dead insects: Use a pressure washer folks, it may take a bit of loose paint off as well, but it will improve the cooling. I do this every year before the annual service as I clean up underneath to make working under the car pleasanter in winter so that my rad never gets gummed up.

3. That the engine waterways are full of calcium or rust and not circulating the water as designed. That's why it's a great idea to have an engine go into the caustic tank when rebuilding. Maybe if your engine is that silted up, you can try a decalcing fluid in it, but be careful as it's pretty aggressive stuff and will need a good flush afterwards.

but mainly

4. Running a shade lean on the mixture and / or running timing that is not correct for modern fuels. Even two flats on the carb can make a major difference to running temperature.


So, old as it is, if everything is in order, it should work fine. I agree with Steve, if you need extra fans or shrouds, that's treating the symptom, not the cause. It's a perfectly valid short term solution, but it's not doing anything to rectify the underlying problem.

BTW the experience I have with the Moss repro radiators says stay well clear: Three leaked inside the guarantee, the fourth overheated so badly we switched it for a $10 ebay used unit in desperation and it was fine immediately.
dominic clancy

Dominic...There is nothing intrinsically wrong with the MGA bog basic original cooling system...it does its adequate job if all kit is as original . It is just that it is inefficient for the reasons I mentioned in previous post below and the world has moved on . Unless you are an MGA purist ( and as Seinfeld said " not that there is anything wrong with that") to upgrade to a wee bit of more modern technology is not 'treating the symptoms' any more than using a mobile phone is treating the symptoms of poor antiquated communications. It is called improvement.
EB Wesson below has it right.....
Neil Ferguson

Dominic..on another subject did you end up staying with the same SU needle we discussed many moons ago ..
Neil Ferguson

Although I agree with most of what Dominic says I have a couple of comments.

Firstly be very careful clearing the radiator of insects etc. with a power washer as if you get too close it can damage the thin radiator fins. I found out the hard way!!!!

Secondly I do wonder if modern fuels run hotter. Thinking back to my 30k miles a year days I only remember overheating when I had hose problems (my car was a banger in those days as most As were).

Thirdly when quoting actual temperatures I am not totally confident in the accuracy of 'rebuilt' dual gauges. Someone saying they run at 180 may perhaps be the same as someone else saying they run at 190. I am more interested in variations with running conditions.

Paul
Paul Dean

Just seen that July over here was the 27th hottest since 1659!! And that August is also forecast to break heat records so I guess there will be a lot of MGAs overheating this month as well! .................Mike
m.j. moore

Out of interest I have two rows of louvers in the bonnet of my 1958 Coupe...20 louvers per row 4"[inches] wide...I estimate this has reduced the running temperature 10 degrees from 180-190 down to 170-180...I have no felt seal above the radiator....I know there is a originality issue here as is pointed out to me every time I take the car on a club run!!!.........Rex
Rex Thompson

It is interesting to note how many people think that running 'cool' is good . From both engine and fuel economy perpectives the objective should be to run as hot as possible but never boil..ie leave a margin below boiling ..and also maintain a narrow max min range irrespective of driving conditions.
Neil Ferguson

I did mean to add..but lost control of my button finger....
Wild temperature variations are also certainly not good for the engine. I would suggest that 185 to 195 degreeF, or even 190 to 200 , are good target ranges. ( I use latter ) and that to be running at 170 DegreeF (75c) and from this up to near boiling is too low a start and much too wide a range. The latter is created by a cooling system whose characteristics do not match the needs of the engine very well.. ie it cools too much in normal driving and does not have the capability to effectively reduce the engine temp. when under max load and reduced road speed ( ie uphill).
Neil Ferguson

Hi Neil

Yes, I did use the same needle, and have been OK with it, have you changed?

dominic clancy

I don't think people are worried about water temperature as such but rather petrol temperature. When you see the thermometer edging above 200 and you are expecting the engine to pack up any minute from vapour lock it's no fun driving!................Mike
m.j. moore

Good to hear . I have not changed or experimented ..and it continues to give me approx. 30mpg ( 9.4 m per litre )when I bother to measure plus good response . Very pleased with whole kit...I found a good supplier of the magic lubricant over here in Oz from Aviation supplier...they also use!
Neil Ferguson

Mike... Fair comment ....and that is just another of problems of fan driven by engine speed and producing an airflow characteristic very poorly matched to need. When stationary in traffic at 40c in Melbourne ...whewwww!!! I don't think the mga designers considered that condition.
Neil Ferguson

Hi

Have found this thread very informative, thanks.
I took my car for a 100 mile round trip today. For the first 30 miles, the guage didn't pass the 190f mark, but then I got stuck at traffic lights, not for very long and the temperature started increasing. Eventually when it got to about 220f, I decided to pull in and go for a stroll. The water loss was minimal.
On the return journey, strangely enough the reverse happened. The temperature kept building until after about 20 miles, it was getting close to 230. I was about to stop and then noticed the temperature falling. Eventually it went right down to the 190 mark!

Do you think this could be a faulty thermostat or pump? Also, I read the tips above such as make sure the radiator is free of squashed flies, and consider widening the grill openings, but this seems academic in my set up as my car has an oil cooler sitting in front of the radiator that must restrict flow to the face off almost 40% of the radiator. Is this also likely to be a problem do you think?
Graham
g Victors

Hi, me again!
One other symptom is that I do get a small amount of pinking. So I think that means my timing is too advanced and engine will run hot? But not sure that would contribute to the symptoms mentioned in previous post?
g Victors

On a related topic, I have religiosly followed the fuel consumption of our G*lf TDI and V*lv* wagon and there is a very pronounced summer to winter difference, cold air being the main factor. Here the air temp varies from -30 to +30 C.
I think the main effect is air density being higher in winter causing more drag, but I also think that a hotter engine uses less gas.
Art Pearse

Pinking is caused by advanced timing, weak mixture or both.
dominic clancy

For pinking there is also the possibility that the fuel you use, or the last fill, does not have a high enough octane rating..but the factors listed by Dominic are more likely ..
Neil Ferguson

Thanks I will check out the timing and mixture.
And do you think the oil cooler could effect the cold air flow to the radiator?
g Victors

I have an oil cooler that spends most of its life under a cardboard cover (except in high summer). It doesn't have any effect on the cool running I experience, so I don't believe it has an adverse effect on airflow.
dominic clancy

Dominic
Is your air cooler in front of the radiator, or down underneath?
Graham
g Victors

it is in the standard place in front of the radiator
dominic clancy

Oh ok, thanks. So that's not the answer for me then
Graham
g Victors

This thread was discussed between 27/07/2014 and 07/08/2014

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.