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MG MGA - Am I overheating?
|I took the car for a good drive the other day. It was an unusually warm day and temperature of car stayed more or less steady at 190 degrees. However towards end of drive I came off a fast road and straight into a traffic jam. Temperature started to climb to just under 212 but then traffic cleared and as I drove off, within a few minutes, the temperature had dropped back.|
My question is whether the increase to 212 is normal, or should the temperature have stayed at 190?
I should add, though not sure its relevant, that by then the idle, etc was not as smooth as normal. But when I got home I found one of the dashpot lids had worked its way off.
|Graham M V|
The temperature will climb as you slow down because your water pump has also slowed,and air flow through the radiator decreases also. The water will continue to absorb heat from the engine wut with decreased circulation will increase in temperature. With reduced air flow through the radiator, it will take a little longer to dissipate the extra heat. When I shut off the engine on my old Ford, I find that the block temperature usually rises about 15 degrees F. before coming back down.
What you describe is pretty normal. When the engine gets very hot like that the carbies can be suffering with vapour lock which will muck up the idle, so you need to get going ASAP to cool things down. I did all the little things which would help with cooling but found the only thing that really worked for me was to fit a Kenlowe fan. I discarded the unsightly thermostat control and switch it manually independent of the ignition (using the fog light wire in the loom), then I'm in control. I'd probably switch the fan on approaching a hold up and things asually stay around a max of 190. My "A" will normally run around 180 on a hot day with its summer stat. When you switch off on a very hot day the temp can reach 230 and boil over - so having the fan running after shutting off does seem to help prevent this too.
|Graham, if you havn't already got a coolant recovery system, fit one, that will solve the boil-over problem that Pete mentions. My A certainly runs hot like yours, I just ignore it and carry on driving, Nothing seems to happen when the needle hits the high numbers. I think if we all stuck a piece of tape over the temp gauge, we'd be a lot happier!|
|My previous posting may have been misleading. By "boil-over" I didn't mean literally as I am sure Pete didn't either. With a 7lb radiator cap, the cooling system shouldn't boil at 230 degrees, merely expand and loose coolant.|
|The overheating saga again. No so prevalent in the milder airs of the UK as the hot climes of the USA and Australia. I have always been a strong supporter of the original spec radiator and that many refurbishments and replacement designs are not so efficient.|
My radiator is the original specification or as close to it as possible with no additional electric fan, and I have the larger 1800 engine under the hood.
I too was out the other day in the 'hottish' weather. The temperature gauge sat at 160 while cruising and struggled up to 175 in queuing traffic.
I have tested the sensor. It is accurate.
In short, it seems to me that 190 as a standard running temperature in the UK climate is too high.
|Hi. I haven't a coolant recovery system nor an electric fan. Both are probably very good ideas for me to consider, but I think I will wait until the winter and avoid traffic jams in the meantime!|
|Graham M V|
|Close to the end of a 250 mile trip coming home this past Sunday we ran into a traffic jam just north of NYC. Air temp was in the high 80's but on the highway blacktop I'd guess about 100. With the electric fan mounted on the radiator blasting away and the heater on full I was just able to keep the car at around 212 until we got moving again. The car has a five-year old Moss radiator that I think is getting more clogged each year, as this didn't happen when I first installed it.|
In general, the equilibrium point during hot weather driving seems to be about 190 even though I have a 160 thermostat installed. In cooler weather it stays right on 160, so I think the guage is accurate.
But, back to Graham's question: is 212 "too hot" - definitely not!. In Key West parades we have seen above 230 without harm :)
|So how high is too hot? What reading on the guage says "Switch me off I need a break"?|
|Graham M V|
Despite what I said above about my relatively low temperatures, my recent 250 mile mirrors Ken's experience exactly, other than I do not have an electric fan. The deciding factor for me about what is too hot is as much about my own comfort as it was for the engine (It was extremely hot in the cockpit). I also found that in the stationary traffic after almost 250 miles the engine ran rough as the fuel started boiling off. Once through the scene of the crash it took about 3 miles to get the temperature down to to 165 again.
I don't think there is any cut and dried answer to your question. I think you get to know your engine over a period of time and sense what is ok and what is not. It's called experience and gut feeling.
|Graham, Sunday afternoon, after about ten miles of running at about 190; which I consider normal for my car, the temperature went up to just north of 212 and stayed thereabouts. Engine ran sweetly with no ill effects. After stopping the engine, the temperature rose to over 230, but nothing boiled over. I had the heater on "hot" but the air valve closed and the flap in the "defrost" position. My radiator is new, the block waterways are clear and my thermostat is the original "sleeve type". Ignition timing is spot-on and the mixture perfect, so I think the cause of my car running hot is not enough air flow through the rad or inefficient cooling properties of the same. Steve says he has the "original" type radiator, and I think that could be the key to good cooling. I am considering turning the radiator grille slats to allow more air through as they do present a slightly "flat" attitude to the airstream (Moss Motors grille, see picture), but have been a bit reluctant so far. What do you think?
|Hmm. Not sure about changing the radiator grille. Wouldn't an electric fan be kinder on the eye and less drastic?|
I have an oil cooler in front of the radiator and that must restrict air flow significantly I guess?
|Graham M V|
My MGA runs at 170 for most times -on the Scottish tour on some of the steep rally sectioms the temp rose to 200 but soon cooled down on the downhill sections.I have noticed that during this hot spell the guage was showing 190 during a lomg run- it hit 200 after a 90 mph burst for a few minutes. I have a Kenlowe set to come on at 195 doesnt help much when running fast but helps in traffic.It is important I find to keep the Grill clear as on the Scottish tour the Rally plate (which covered around 10 % ) increased the temp by 10 degrees until I moved it
|P D Camp|
you may recall that I fitted one of the new larger diameter moulded plastic cooling fans a few months ago that I had bought from NTG online.
It is significantly larger than the metal bladed fan, I still havent measured its actual diameter but it only just clears the safety finger guard on the back of the radiator.
I also mentioned that the extra diameter and the more efficient curved blades created a much increased air flow, so much so that when I blipped the throttle with my head under the bonnet (hood), it blew my baseball cap off! (ok, it is a loose fit even on my big head)
It has definitely dropped the running temperature by 10 degreesF from 175 to 165 on the gauge.
It is of more rigid construction than the older plastic fans which have round ended blades and are smaller in diameter. So Im confident that it will not flex and damage the radiator. Also I dont intend driving the car through deep water which was another concern as it was suggested that the water may cause the fan to flex forward and damage the rad.
Last weekend during the hot weather I was caught up in traffic for 20 mins or so and the temp went up to 185 / 190 degrees which always slows the tickover down a little, but once I was back on the move it went back down to normal in a couple of miles.
The only downside is that it is distinctly noisier than the standard fan, especially at higher revs and second to the noise from the tappets, it is the most predominent sound from under the bonnet. It sounds a little like the fan cooling you hear on a double decker bus, which is a shame as this not quite the image I wish to project!
Im thinking about the twin electric fans for the future which could be worth experimenting with. They seem to work ok in Australia so you would expect them to cope over here.
|I sometimes wonder if there are variations in the standard MGA fan. i.e. did MG alter the pitch of the blades at some stage. It seems strange that some of us appear to run noticeably cooler than others. I know I harp on about the original spec radiator, but the thought occurred to me that there could be another simple reason. Colyn's comments about his plastic fan could be a clue that the fan blade pitch was increased slightly at some stage.|
|Some years ago I fitted a plastic fan approx 13" dia and it solved my slow moving overheating problem completely. The fan is quite close to the radiator that I had to move forward on packing for clearance. But for me cooling at high speeds on a hot day can still be a problem where the fan has little or no effect. There's a long fairly steep hill just outside Exeter on the A30 that is a test for my car and the temperature rises to around 220F, and about the only time I resort to the heater.
|J H Cole|
|I have encountered persistent overheating in over 40 years of MGA ownership. Both of my 1600's (roadster and coupe that I have owned for about 30 years) have overheated on warm/hot days. All sorts of theories have been advanced, core type, fan blades, etc. I think it is an airflow problem, the factory took out a few grille slats at Sebring on warm days. Suffice it to say that I have the radiators rodded out every two or three years and this (temporarily) overcomes the problem. When we entered our 1600 roadster at Silverstone some years ago all of our rivals had electric fans! With their attractive aerodynamic shape, I don't think that enough air comes through the grille/radiator, MGB's have a vertical grille which dams the air!|
|I stopped for a new MGA owner with the bonnet up just last Friday just off the ring of Brussels. He had a car that had obvious overheating symptomes which had come on due to sitting in the traffic jam that is the bane of my homeward journey.|
Looking at the car I could see that overheating was not new to this car. The kenlowe type fan fitted to the rad is always a give-away.
Looking at the radiator I saw immediately that it had been given a modern re-core, "much more efficient with all those extra cooling surfaces sir". My advice, scrap it and buy an original cored radiator. I have run mine for 10 years now, after 10 years of problems with a modern re-cored unit, and the temperature remains where it should. I bought mine from Brown&Gammons in the UK but I am sure that others supply the correct unit.
A Kenlowe fan is good if you only travel in town or at low speeds but should not really be required if you are driving the car in a normal manner.
Making sure the engine is in correct tune and using a rust inhibiting coolant is also good practice. See many other posts in the archive.
|Neil, like you, I don't see that electric fans are of any use other than when the car is in slow moving traffic. Surely having two fans in front or behind the rad is going to hinder airflow at normal road speeds to a certain extent. I always understood that thermostatically controlled electric fans were used to get a better control of engine temperature, i.e. allow quicker warm up and release a couple of extra bhp by not having to drive a fixed mechanical fan all the time. Nearly every MGA fitted with an electric fan that I have seen, still has its water pump mounted fan as well! My car seems to get hotter when I'm belting along on the open road, and drops when I'm poodling along at 30mph. As I said before, it is as if the radiator is not cooling the water sufficiently. The first 5 or 10 miles of the journey, it doesn't matter how fast I drive, the temperature stays at 190. It seems that in this hot weather, once all the water in the rad has been warmed up it then climbs to 212 plus. In cooler months the water temperature rises rapidly to 190 and stays there.|
|Picture of my plastic fan which shows how it differs from JH's fan shown above.|
|Forgot to add that on the drive home at the weekend at a continuous very high speed run over 4 miles, the temperature rose from its normal 165 to about 180 or so. It rapidly dropped to normal once I slowed down.|
Does anyone think that the mechanical fan actually restricts the air flow through the rad at higher speeds?
Or do you think that is more likely that the engine compartment will only allow so much air to flow through it at high road speeds and the resulting build up of pressure stalls the air flow?
Does anyone have a spare wind tunnel to check this out?
|Lindsay/Neil..interesting to read about your comments on electric fans.|
May I illuminate you on how,if they are properly fitted,they are supposed to ( and do) work. I myself fitted twin fans and removed the belt driven unit that consumes energy through the whole speed range whether needed or not.. I did it because I found the temp varied quite wildly with the old system..but you do have to get the system spec right.ie enough air being forced through the radiator.
The fans are designed to cut in and cut out after order of 1min and control the water temp over a limited range..which is excellent for engine efficiency( and wear, structural deterioration ..whatever!!) . I have set mine to come in at about 195f and they cut back out after they have cooled order of 8F..I use a 185f water thermostat.
When I garage tested them they created on almighty blast.
So here in Oz ( it is occasionally hot here as well..i se you are suffering in Blighty) I find that the engine very rapidly gets up to the above range and stays there whether in slow traffic or at speed or even climbing through the Great Dividing Range of mountains near where I live.
They must create some limited extra friction when not on but this becomes irrelevent if they have enough capacity when they are on.
|Sorry to move slightly off thread, but whilst we are debating air flows through the engine bay, what does the air hose on the left (carb) side do? Is it important, is it to keep the carbs cool? - Needless to say, mine is missing.|
|Graham M V|
|It takes cool air from well in front of the radiator to the air intakes of the carbs and cool air means more oxygen etc ,more power. Without it the air would be mostly from backside of the radiator and much hotter.|
|It almost certain that it is airflow through the radiator that is the problem. The faster you travel, |
the more overheating problems arise, as has been said (and from experience) reducing speed brings the temp down! With cars fitted with heaters, there is large trunking just behind the grille but hardly any air reaches the cabin. I think that confirms the theory.
|I followed Barney's fixes: Got rid of the original 4 blade fan, got the 6 bladed plastic fan, installed a radiator/fan shroud, coolant recovery tank, etc. Even at 94 degrees Fahreinheit air temp, pulling a long mountain grade (with one almost dead cylinder) and carbs on the lean side, I never went over 212-215 degrees with a 185 degree thermostat. After about a quarter of a mile after reaching the top, it was back down to about 190-195. |
But my radiator IS the original design (maybe the original that came with the car?) and has just been recently cleaned out/checked out. I'm using a Stant 10 lb. pressure cap and 50/50 anti-freeze mix.
I believe I could expect even better results by adding Water Wetter.
I thought MGA original fans were 6-blades, not 4.
|Steve--the one I took off of mine had 4 blades. In fact, it was a 2 piece fan. 2 separate blades bolted together in an X pattern giving 4 surfaces. I assumed it was original, as the rest of the car seemed to be original. |
If the original fan was 6 bladed, I can't imagine someone putting something like the 4 blade unit back in as a replacement. What a step backward! But maybe that's what "aftermarket" blades looked like back in some dim past?
|Jack, what year is your car? Mine is a '56 (built mid April of '56) and, when I bought it 6 years ago, it had the same type of 4 bladed fan that you describe. Like you, I have no way of knowing if it was original to the car.|
I asked about the fan some time ago and was informed that those 4 bladed fans were used on the Magnette. Could they have also been fitted to some of the early MGA's as well? Might it have been a case of using up some extra Magnette fan blades on the MGA production line? Or did a PO replace a faulty fan blade with whatever he could find that fit? No real way of knowing.
By the way, I have since put a "propper" 6 blade fan on my car. I flushed out the original radiator, use a 50/50 anti-freeze mix with Water Wetter, have fitted a radiator shroud, replaced the missing felt pad on the underside of the bonnet, have both carb and heater side duct tube fitted, and use a blanking sleeve along with the thermostat. I have no problem with overheating.
|Andy--mine is a '59 1600. So that's quite a spread. What year did Magnette production end? I'm not even sure I can recall what a Magnette looks like. They would be very rare in this part of the country.|
But perhaps an MG dealership would have had the 4 blade unit as a cheaper replacement alternative to the 6 blade unit? Like you said, no real way of knowing.
I know one thing, though: I'll be a little more careful with the word "original" from now on! :) (Unless I'm dealing with the suckers on e-bay--LOL. After all, you and I have RARE, original, 4 blade fans!!! Only installed on a few, very select vehicles!!!)
I don't have Clausager in front of me for reference on originality. It is still in a packing case somewhere in England, so someone else will have to advise if 4 blades were ever fitted on early cars. My original engine on my 1958 car came to me with 6 blades. Diagrams on-line with Moss and Barney's site also show 6 blades.
|I have in my hand an original yellow MGA workshop manual for 1600 and 1600 MKII.. The fan shown in the cooling section is steel with the blades riveted on and there are 6 blades.|
This is publication AKD600D.
|My bet is that the early ’55-’56 were fitted with the four bladed fan leftover from TFs and ZA Magnettes.|
|Only 6 blade fans shown in 1500 parts book. 4 blade fans came off other BMC and other makes of cars.|
All fans are only useful at low road speeds, and can block airflow at higher speeds, but the MG ones are not of the blocking sort generally.
Back long ago, we never had problems with high speed overheating, but replacement parts were good - ie, to spec. It might be good to ensure that the air ducting is arranged correctly, ie not disrupting the airflow to the rad, especially if you have an oil cooler on top of the shelf.
I will point out that having the heater "full on" but the air valve shut is pretty pointless.
Restricted exhaust is the primary cause of high speed overheat, assuming the car is fundamentally right, so suspect your muffler, or the mousies. Flattened exhaust pipes are good for this too. The only real way to tell is to fit an exhaust backpressure measuring device, but simply removing the muffler for a test run might tell you something. I note that stock MGA size (1 5/8) pipes are marginal on stock engines at full throttle/high speed and definitely undersized for 1800. Best to go to 1 3/4 OD (MGB size).
Jaguar XK120 had a very small air intake for a big rad/engine, and a rudimentary fan - they gave you about 4 traffic lights before the temp was in the OP section; over 40 mph no overheat ever. For the US XK140, they fitted a 12 blade fan, which worked great at crawl speed, but caused overheating on the highway. My 120 overheated at both ends, traffic lights for sure, but also over 60mph, when the temp gauge was just like a speedo. Turned out the DPO had reduced the twin 1 7/8 XK120M pipes to a single 1 1/2 at the (early Healey) muffler, then back up to twin for the tailpipes. A couple straight through glasspacks and 1 7/8 pipes cured that, and it went a whole lot better too.
|Fletcher R Millmore|
|Clausager states on page 64 " The same six bladed fan was found on all cars including the twin cam.It was painted black on early 1500 models but was changed to red in 1958.Most twin cam and 1600 models had red fans.On the 1600 MK2 and possibly some late 1600 models the fans were yellow. BMC replacement fans were typically black"|
|P D Camp|
|I would imagine that there is nothing worse than "a Mousie in your Muffler" Fletcher.|
I cant see why anyone would stuff long tailed ice fishing bait maggots into their silencer (imagine the smell!), or a bunch of childrens whimsical porcelain figures (imagine the noise!). Or even a family of mice, sounds a little cruel to me although I suppose a little extra squeaking on an MGA would probably go unnoticed!
Doesnt sound so much fun but we tend to use glassfibre wadding and other similar materials over here. Or is there yet another meaning for mousies that I have missed?
Interesting about the exhaust pipe diameter Fletcher. My car has an 1800 engine fitted and it does get between 15 and 20degrees warmer after a (very)high speed run.
I will check on the diameter of the pipe to see if it is MGB size.
The grill was mentioned earlier, I find all the MGA repro grills appear to be blocking air flow to the radiator, some seriously I'm sure; they have a curved look from the front view. I gently twisted mine round in stages using pliers at the top and bottom until the grill 'blades'(?) looked more or less vertical and straight from the front. Then you will see the curve nicely fits the body profile shape - surely what was originally intended. This is a lovely clean little job and you can take even longer with your MG bonding getting all the gaps just perfect. This has to let in more air. ...and you will find it easier to poke something through to release a jammed bonnet!
Steve I'm convinced you are right about the original spec rad, when mine gives up the ghost I'm going that route. My rad is newish but thinner than what I believe the original spec rads were - 2"? I keep my cleaned system dead clean by only using filtered distilled water from the de-humidifier in my garage - why chuck it away when you can top up batteries, steam irons, etc. I use 1:2 A/F mixture with this and water wetter. I have made up a rad to bonnet seal, timing and mixture is good, but it still needs the electric fan in a jam on that hot day with its standard engine driven six blader too. The distilled water would also gradually clean-up a furred-up system each time you refill, the anti-freeze with its inhibitors keeps the corrosion to nil. Change the anti-freeze every two years, only topping up with the correct mixture too.
Something else I must check out is the fuel we have to use now. I understand ethanol is used a lot, certainly in V-power. I have seen mention that you need more fuel to get the same sort of power and that richer needles might be needed - this just might make sense to keep things cooler at speed when mine certainly gets hotter...
I still very well remember that two year old "A" I had in 1963 - absolutely no overheating, no electric fan; thrashed the pants off it, (110mph indicated with the hood up) flat everywhere, she never missed a beat and temperature wasn't an issue! Magic, that's why it had to be done again.
It's Bob West and his mechanic James who converted me to the original spec radiator. They see a lot of overheating issues with customers and many are caused by the 'slim-line' cores etc. Bob has done much research on the subject and has sourced a supplier who does all his re-coring - close as possible to the original within modern metric availability. For this reason I only ever use his exchange radiators.
I run the 1800 with an MGA diameter exhaust. 155 to 165 degrees on routine runs. Standard radiator, no electric fans, no oil cooler, fairly open slats, cheapest basic thermostat. It's all down to the radiator, believe me.
|Pete, I have looked at lots of head-on pictures of MGAs and notice that many have their grille slats twisted to give a more vertical rather than cuved appearance, indeed the three front end comparison pictures on page 21 of Clausager show almost vertical grille slats. Personally, I think they look better than the flatter, curvy ones on my repro grille. I also have a standard grille which has quite a pronounced curve to the slats when looked at head-on, but probably not as pronounced as the repro grille, the standard grille also shows more "daylight" between the slats. So I have removed the the grille from the car and will perform the slat twisting operation tommorrow and report back on the difference, if any, that it makes.|
|Looking forward to your observations on your cars running temperature once you have modified the grille slats Lindsay.|
I have always thought that the slats on my car look as if they are competely blocking the airflow.
|Meant to upload a picture of my grille but pressed the submit button by mistake|
|Some years ago an Australian core manufacturer was making "finned" replacement cores (similar to an MGB) for MGA's but, to allay complaints of overheating, recalled them and had new "cellular" (as per the original design) cores fitted free of charge. One of my cars was one of them. In my case, at least, it made no difference whatsoever!|
|I have been considering Lyndsays earlier observation that almost every car he has seen that is fitted with an electric fan also has mechanical fan fitted and my thought that maybe the airflow through the rad stalls at high speed due to air pressure build up in the engine compartment.|
(I know there has been a couple of days between the posts but my thought processes must work very slowly nowadays)
I wonder if the maybe mechanical fan becomes the sole provider of airflow through the rad when the air pressure builds in the engine compartment at higher road speeds?
|Colyn, your grille slats look very much like mine, and as you say, they do look like they block the airflow. Does your car overheat? If it doesn't, maybe I should be looking in another direction. I have tried tweaking the grille slats and don't seem to be able to make any impression on them, I am a bit reluctant to resort to brute force on my shiny and relatively new grille! Is there a special technique to this procedure, anyone?|
|No Lindsay, I am lucky like Steve in that my car runs relatively cool according to the gauge, 165 F is its normal setting. It rises to 185 ish when I push it very hard (at say well over 4000rpm in top gear) for a long period of time or if I push it hard up hill for long periods. Stationary in traffic it sometimes shows 190 and seems to be quite stable at that though I sometimes use the heater to bring it down. The tickover slows noticeably at this temperature to about 500rpm.|
My new "big yellow fan" has certainly made a difference as it has knocked 10 degreesF off the normal running temperature but the double decker bus noise it makes does get on my nerves a bit.
So my main interest here is to improve airflow through the rad at higher speeds, to reduce the power losses that my big fan must be causing and to get rid of at least one source of the continuous whining noise in the car!
(Hope my wife doesnt read this !
The irony is that my wife, who is quite fond of talking at length, was horrified to find that the faster I drive, the less I can hear.
And now with the new fan, the faster I drive, the worse the fan whine becomes.
So I suppose it serves me right! )
|Well I have read it! Fond of talking at length.... thats a nice way to talk about me in front of all these nice people!|
There will be no dinner for you tonight. And as for the other stuff, you may as well move into the spare room!
LOL - only joking, not your wife - just having a laugh!
do the fans on your ventilator have sharp edges? If so try to soften or round them with emery cloth or a fine file. This cured the noise on the fans of aircooled engines back in the 50s.
|Managed to tweak the slats on the repro grille so that they match the original grille I got with the car, and have seen an improvement in temperature. On the open road today, the temperature at 60 mph was just above 190 degrees, before the grille modification i was seeing 212+. Interestingly, before I modified the grille, the temperature would drop to about 200 when I slowed to 30 mph or less, now I find the temperature rising to 200 when I slow down or stop and decreasing to just above 190 when on the open road again. I tried, but was unable to get the temperature to 212 degrees today, whereas last week I was seeing highs of 220+. So although it is maybe not quite as hot today as it was last Sunday, it would appear that the grille slat angle does have a significant effect on the radiator's ability to shed heat. The picture shows the slats after modificatoin, still maintaining their "correct" curve but with more space between them. |
|Phew Siggi, just for a moment there I really was going to pack my things and move into the spare room! you had me worried there!|
Thanks for the info about the fan noise, I should have realised that someone from the country that gave us the air cooled Volkswagen should know something about cooling fans!
I will have a look at the fan over the weekend.
Looks like you have done a fine job there, what did you use to open up the gaps between the grille slats so that they end up with such even gaps?
|If anyone's curious about the "rare" 4 blade fans that were discussed earlier, here's a photo.
|Colyn, used a small pair of flat nosed pliers with tape wrapped round each jaw to stop them marking the vanes, then just tweaked the top and bottom of each slat a small but even amount. I ran through all the slats, compared them to the original grille, then repeated the operation until after three times through it looked right. I think the secret of getting them even is to do a little at a time rather than trying to do it all in one go. I am very pleased with the result, gave the car a really good thrashing through the heat of today and could not get it any hotter than half way between 200 and 212 (heater off). Judging by what Barney says about temperature, I would say that is about normal for an MGA with a standard engine and cooling set up. Also noticed more hot air through the heater when it turned a bit chilly this evening.|
Graham, I don't think you have got anything to worry about! Your tickover problem was most likely caused by the loose dashpot screw. Even when mine was getting stinking hot, it still ran ok. It was only when I came to re-start the engine while it was still very hot that it faultered for about 15 to 30 seconds and then settled, presumably once the carbs had received some cool fuel.
|I beg to differ Lindsay. I cannot see how, in the UK, hot as it is at the moment, that 200 to 212 can be considered normal for an MGA.|
I have never had my 'thrashing' temperature above 185 over the past 10 years. My 250 mile run the other day in very hot temperatures was done at 70mph all the way with the occasional excursion to 80. Temperature sat at 165 at these speeds.
There has to be something awry with your cooling.
|Steve..given the age of our beauties and the numerous kit differences etc I am not surprised at the differences in energy heat balances and therefore water temps.. I am also of the belief that there is nothing untoward about an occasional temp of over 200f. The system is pressurised and whilst I dont have the precise fig to hand i would believe the temp could go up to 235f or thereabouts before boiling. I also believe warmer is better for most aspects of engine system performance ..although you should keep a deltaT margin for very arduous driving conditions.|
My belief is that your 165f is the other end of the extremes...ie it is too low!
|Does anyone know what the optimum temperature of the engine should be for either max power or efficiency? I ask this because sometimes the issue comes down to the avoidance of boiling and any other consequential problems like vapour lock and at other times its the pursuit of the lowest possible running temperature such as around 170F (totally unachievable for me). The normal running temperature of my engine working moderately hard on a warm day is around 190F and it seems happy at this level. However the works manual says it should be 160F! If the manual is correct it goes to show how far most MGA setups have moved from the original spec -or possibly how differently we drive our cars, motorways etc.|
|J H Cole|
|Also Steve.. your car isn't exactly standard. You have a "modern" underworked 1800 striding accross the country with its high 5th gear, I have a poor little 1500 running its legs off to keep up! As Neil says, 200 is about normal, check the temperature of the MGA in this YouTube video at about 5:20 http://www.youtube.com/watch?v=Ny88QHG-PuI. Looks like over 212 to me!|
|Barney's temperature takes some beating though! http://www.mgaguru.com/pic89/trmont.htm|
|Barney has an excellent note ( Co-101) on this and the unnecessary 'worry' by citizens over water temps.. I use a 185f thermo so only on take off can temp be below this level . I set my system up after reading the above.|
JH Cole..I suggest your thermo is aroung 185f as well so under op conditions it can never get down to the actic levels of Steves as all your coolant would be taking the short circuit.
NB do you operate just with a blanking sleeve ,Steve ?
According to David Vizard the best compromise operating temperature for efficiency and power is 180 degrees F.
You need the higher temps to help boil off condensates in the oil.
|JM So can anyone suggest why we have moved so far away from the advice in the workshop manual? page: 'general info 3' thermostat opening 158F to 167F, running temp 160F.|
|J H Cole|
|My stab at the subject would be that the cooling water normal temp setting has always been a compromise between a number of factors..and talking just about the major directional ones...|
..The higher the temp ( and the more constant such is )the better for combustion and differential temp.thermal stresses etc in the engine block etc.
..the lower the temp ( within reason ) the higher the bearing properties of the lubricants.
The second has changed with much better viscosity versus temp properties in oils today ..allowing higher temps without loss of oil bearing properties.
My underworked 1800 is still filled with the pure soft water of the North West. Better than Yorkshire and Fens water. May be that accounts for the lower temps. Let's see what London water does for me next time I flush through.
Perhaps we could start marketing our pure Lakeland cold running water to the States and Australia.
Alternatively, I have been running fully synthetic oil (10-40), so may be I have less friction.
Seriously though, I used to run a Smiths sleeved thermostat and I ran at 175 to 180 degrees. About 15 months ago I noticed the average temp creeping up to 190 to 195. I changed the stat to a bog standard one and the temp has sat at 155 in winter and 165 this hot summer (hot for the UK).
|I am a bit confused. I thought the idea of the thermostat was to help the engine to heat up quicker. What am I missing? If I just removed the thermostat, would it run cooler?|
|Graham M V|
|Steve, my water is the distilled stuff out of the de-humidifier, so I don't know exactly where it came from, probably something me, the wife or the two dogs breathed out; what a horrible thought! Engine oil is Castrol XL 20/50 ( contains ZDDP - missing in modern motor oils - needed in classic car engines http://www.ttalk.info/Zddp.htm ) Engine oils are designed to operate at a temperature between 180F and 220F (upper viscosity measurement is taken at 210F) so my engine is now running in the middle of that range, so as long as it continues to run as sweetly as it does now, I won't start worrying untill it crosses the 230 line!|
|As an additional thought regarding temps--oil temps will be roughly 10 degrees higher than water temps. So a 185 degree water thermostat puts the oil temp close to the sweet spot that Lindsay notes.|
My shielded Smiths thermostat was giving up the ghost by not opening. I spoke to the supplier and apparently it was old stock when he supplied it to me some 8 years previously. It was quite possible that it had never worked properly. Once I put the new winter thermostat in the temperature dropped like a stone. I was somewhat surprised at these low temperature the car was now running at, but when summer arrived I fitted another thermostat and it still gave the same low running temperatures.
|Graham - I too am confused. I have a 185 winter thermostat fitted (yes I know it is summer now)and my temp gauge sits at around 190 most of the time. So I thought that the normal running temp gauge reading was dependent entirely on the thermostat ( which holds the engine temp at the minumum set on the thermostat).|
|The thermostat does not control the temp..it sets the minimum temp ..not the maximum.|
Whilst the engine ( and coolant ) is heating up the thermostat diverts much of the water directly back to the radiator until the thermo setting is reached ..and then the thermo opens and more water goes through the engine ..if too much heat is being generated by the engine the temp continues to increase until it reaches a thermal balance at a higher temp ( hopefully !!).
As an additional thought on the subject and based on Steves and other experiences on this thread and presuming about the same heat load to the coolant as Steves machine it is possible that some cars with pulley driven fans and with a higher thermo setting ( eg 185f ) have a condition where the thermo is only partially open....or is opening and closing because at the higher temp it needs less coolant to maintain the thermal balance.
This thread was discussed between 19/06/2010 and 06/07/2010
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