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MG MGA - My Running Temp

I am aware that I am renowned for harping on about having the correct spec radiator for cooling the MGA. I also suspect there are a few of you who doubt my claims about running at 170 to 173 all day. So, I went for a quick 20 mile run round the area as the sun was shining and it was a warm and pleasant 20dC and took a photo of the dashboard. When I got back I sat idling for 10 mins. See photos. I then took off the radiator cap and took the temperature with my digital gauge. It showed a corresponding reading to the gauge.

Steve

Steve Gyles

I know what the problem is...your gauges are in the wrong place!!!
Gene Gillam

Steve - I'd be more than happy to send you a gauge that works...no charge...
Bayard DeNoie

I think you must have fitted an extra end stop which prevents the needle going past 175 Steve!☺

Either that or you are really good at Photoshop!

Stay Cool Steve.

Cheers Colyn

Colyn Firth

Steve, I'm interested in your observations as, at the moment, I'm doing tests on my radiator (3 row tube and fin) comparing it with an original style cell core type.


Can you tell me what temp. thermostat you are using?
Also do you have a standard MGA water pump?

What is your idling rpm and during your idling 10 minutes was the bonnet raised and did you take the temperature with the engine still running?

I am currently monitoring temperature (thermocouples) at four different points under the bonnet and I have a flow meter inserted in the top radiator hose.

I have found that after ten minutes idling the coolant temperature on mine has not stabilized. In fact it is still slowly creeping up after 30 minutes idling at 6-700rpm!

It's early days but one interesting finding so far is that there is a large temperature difference between the front and rear carburettor bowls with the front one being 10-15 degC hotter than the rear after 40-50 minutes idling.

It's a slow process as I have to wait for 20 degC days to take measurements! .....................Mike
Mike Moore

Mike

I was struggling to believe my cool running hence some of my basic observations today. I run the 1800V with an 1800 short pump. I also run an MGB expansion tank with 50/50 antifreeze and the 7-blade asymmetric fan. Other than that all else in the cooling is standard. I can't remember what stat I am running but am going to have a look to check it's working okay.

I did have some interesting observations when I switched off the engine and checked the water temp at the top of the rad. It remained at 175 on my digital thermometer, whilst the MGA gauge maxed out at 190. When I fired up again with both rad caps still removed both temps stabilised once again at 175. In other words I could not get the water at the top of the rad to rise above 175.

Idled at 800 to 900.

Steve

Steve Gyles

Steve, I too rarely get past 175 F even at 30 C ambient. Original rad, 1622 cc. But lots of heat from the heater if needed.
Art Pearse

Steve
I have never really understood this. My car was definitely running too hot, especially in traffic, which I have been working on.
But my question is, should our cars really be running as cool as 170dF or 175dF? What should the optimum temperature be? Engines run best when up to full temperature, whatever that is.
As I understand it, the standard MGA thermostat doesnt open until it reaches 82dC (180dF) which means to me that the car was designed to heat up above that.
And then there is the radiator cap, putting the system under pressure so the water doesnt boil at 212 dF.
I am absolutely certain your car runs very well indeed, but I am uncertain that we should all be striving to be that cool.
Have I missed something simple?

Graham
Graham V

Steve,
Peter Burgess (How To Power Tune MGB) recommends 190f (88c) for developing max power in the 1800 engine. My own runs at 180 flat & idle but will climb to 190 on hills. I really think 170 may be a bit chilly if that is max.
Bayard DeNoie

Steve......I Agree with other posts ....170 is too cool. Temperature should preferably be above 180 ..better still 190 .I suggest a change of thermostats ....
Neil Ferguson

Steve..do you have a blanking sleeve in the thermo housing? I have a 160 thermo and after putting my new plastic fan on my car I found I was running at 160 or just over even in summer but during recent head work noted I had put a blanking sleeve in a long time ago. Took the sleeve out and the car now runs at 180 to 190...air temp about 18. Taking it out means the car warms up more quickly but does mean more water by passes the radiator .
...or as an alternative have you considered swapping that efficient over sized radiator for bog standard Moss unit ( tongue in.....)
Neil Ferguson

Better yet, Steve...add air conditioning...I can guarantee your engine temp will reach, and probably exceed, that optimum zone 8^)
Gene Gillam

Consulting a bible, Vizard , ( for the A series engine ) advises me that max power is at 160f and max economy at about 212 to 220f ..so averaging gives 188f. ..very very close to Bayard's comment re Peter Burgess above. I have also read same about other engines of the period ...
Neil Ferguson

I'll stick with max power then!!!!

Steve
Steve Gyles

Not surprised at that answer from an ex Lightning pilot..wonder if a Ryanair pilot would go for the 212f
Neil Ferguson

Re my previous post about removing the blanking sleeve (with some drilled holes ) ckoke-in and warm up is now much faster ..not surprisingly..
Neil Ferguson

The way I conceptualise it, right or wrong, is
1) The denser (cooler) the inlet charge, the greater the density of combustable hydrocarbons in any inlet charge. (i.e. the more molecules of fuel for a given intake volume), and, potentially, the bigger bang.
2) The higher the temperature at which combustion takes place, the more complete the burning and, again, the biggest bang.

Hence the carburettor cold air duct needs to be in place, as most of us have, and, I'd have thought, as a high a thermostat opening as is practical for otherwise satisfactory running.

For what it's worth, I recently had my exhaust manifold "Jet" (ceramic) coated, and at the same time swapped my 72C thermostat for an 82C opening type.

Can I notice the difference?
Well, the engine bay temperatures are definitely down (no more fuel vaporisation when restarting soon after switching off (previously manifested as irregular running for 20-30 seconds after re-starting on hot days and after longer runs), and palpably less heat conduction into the cabin).
Can I sense a greater power output through the (admittedly subjective) "seat of the pants"? To be honest, no. Perhaps an exhaust analyser and rolling road/dyno might demonstrate a difference, otherwise, no practical difference in regards to the higher running temperature.

T Aczel

Just had a look at my thermostat. It's an 82dC (179dF). Functioning okay, but on calibration it's opening at 76dC (170dF). Ties in very accurately with my gauge readings. It's only a few years old. Makes you wonder?

Off to motor factor for another. May be I can get the engine back up to 175 to 180. Will report back.

Steve
Steve Gyles

Motor Factor (Halford) does not keep them in stock so ordering from MGOC. Of interest I noticed that the MGOC spares showed 74, 82 and 88 stats for the 1800 engine. Anyone ever used an 88?

Decided to also change the expansion tank cap. I did a few measurements and it seems the cap only comes under about 2mm of linear compression (7lb cap). Is this about right or should they compress further?

Steve
Steve Gyles

I just cooked 3 off my store of thermos on the stove( they did not soften) and found little correlation between the stated opening and actual opening temp. I have replaced the one in the car ( 160f) with one that starts to open at 180f and is fully open at around 187... Though it says 195f on its body.. I wan to operate around 190 . I have the plastic fan and the twin fans cut in at 195 ...so after it is fully open a gale starts if temp keeps rising.
Neil Ferguson

Neil
have you refitted the engine driven fan to run with your Twin fans then?

I'm still running twin electric fans with no engine driven fan fitted and they seem to cope well with the cooling of my 1950cc engine without it.

Colyn
Colyn Firth

Tom,

I'm happy to hear of your JetHot experience with the MGA exhaust. I had the extractor manifold for my TC JetHot coated and it's amazing how quickly it cools after a run so I've been thinking about doing it for the MGA this summer.

Yours looks great, btw.

Gene

Gene Gillam

Colyn...indeed I have .i did it after a hot incident about 5 months ago..not the fault of the twin fans ..but just disturbed wiring after my hands being under the bonnet. I don't have the twins cutting in until 195 . Thwassymetric plastic fan is very good ss well. ?.so belt and braces.
Neil Ferguson

Not so long ago I bought a cooler thermostat, 74degC (165degF) to replace an 82 (180).

Checking them both I found that although the 74 stat started to open at 74 the one I had in (82)was opening at 70.

Also the temperature range from start to fully open is around 20degC................Mike
Mike Moore

Mike

It does make you wonder about quality control with the manufacturers. I will certainly be testing my new one before fitting.

I have answered my own question about radiator cap linear compression when fitted. Just measured up my MGA cap that I don't use with the expansion tank system. It too compresses about 2mm when fitted - the width of the rubber sealing washer.

Steve
Steve Gyles

Just got the MGOC thermostat. Calibrated it. Spot on. Started opening at 82 and fully open by 90.

Seems that these are items to be watched. I wonder how many others have checked theirs out? My other 82 stat opened 6 degrees early. It would be interesting to see if any open, say, 6 to 8dC late. this could give base-line operating temps of 190+ on the gauge before we get into the issue of radiator originality!

Steve
Steve Gyles

The difference a correctly calibrated thermostat makes. Settles at about 178 to 180 but I was watching it jump up and down between 178 - 190 as the stat opened and close during the warm-up cycle combined with rapid cooling with the 7-blade fan.

Steve

Steve Gyles

Steve,
That makes me feel much better: maybe I don't need to change my radiator, fan or thermostat, except when in very heavy traffic or driving faster than I should.
Shane
Shanerj

So Steve, after all this time of discussing your cool running, original radiators, etc., are you now saying it was all down to a thermostat setting? Just to be clear!
Bruce.
B Mayo

The question is, I think, not what coolant temperatures one sees cruising around, which most of our cars manage ok, even the ones with marginal cooling capacity, rather what happens to the coolant temperatures in more difficult conditions such as when idling when caught in traffic jams for longer periods and long uphill gradients (mountain passes etc) in hot weather. Does the temperature then start to climb significantly above the temperature at which the thermostat has opened fully?
T Aczel

Steve
I think they are teasing you. And whilst I have always argued the engine should not be too cool, we need to remember that all the thermostat really does is determine the temperature at which the cooling system starts to kick in.
Graham V

Steve, In your setup you seem to have three items 1. an original style radiator 2. a (presumably) higher output MGB water pump and 3. a seven bladed fan all of which could have a bearing on your engine cooling.

I guess from what you've said in previous posts that you believe 1. is making your cooling system ideal but do you have any evidence that 2. and 3. might also be having some effect?

I wish I had the luxury of being able to control the running temperature by changing the thermostat. All a lower temp stat would do for mine is delay the inevitable..................Mike
Mike Moore

Bruce

Lol. What it has shown to me is the efficiency of the radiator and the 7-blade fan. The old thermostat was behaving like a 74dC version and my system worked at a rock steady 170 with hardly any discernible needle movement throughout the operating range. With the calibrated 82 stat the variations are noticeable. You can observe the stat opening with sudden drops in temp as the 'supercooled' water is released back into the system. The stat then closes and you can see the temp creep back up to opening time again etc. Once fully warm the variations dampen a bit but the top temp has not gone above stat opening time (180 to 182 ish) regardless of speed and load. It's normal running temp is looking like 178 when fully warm. Still looking for that elusive traffic queue around here, but idling in the garage has not shown any rise above the norm.

Steve
Steve Gyles

Steve

Interesting to see you are now very near to my figures also with a Bob West radiator core. Yes I did get an improvement, probably around 5 - 10 degrees, on my radiator change 2 years ago.

You may find it difficult to find the conditions to get the temp to go up. It is very rare for me but it can happen, only once this year in a very long steep uphill jam in Whitby coming back from the Register's north weekend. I guess you don't have many long steep climbs around you?

Paul
Paul Dean

I have a few good climbs on the doorstep. My car goes all day without overheating even in 30c plus temperatures.

dominic clancy

I would be interested to know what temps others run at who are using the 74dC stat. My datum for that was of course just a tadge over 170 with the out of tolerance 82 stat that was acting like a 74 to 76.

Dominic. You used to run cooler than me. Did you ever resolve it or just go with the radiator blind?

Steve

Steve Gyles

I have a radiator blind. But with Steve's extra testing I am intrigued - I think I have an 82c stat and since I took the oil cooler out of service (the connections got in the way of the new sway bar) my car is now running at a steady 80C, which is great - I have just come home from a run and its 30C outside and the temp rose quickly to 80C and stayed there, even in a traffic jam in a tunnel. I suspect that it will still need the blind to be used in winter, but that is what it's there for.

Next engine change (I'm still waiting on a few carb bits before the new Judson engine goes back in after it died last year at 30km because of a strange bearing problem- mains and cam bearings were shot on dismantling, so there was some crud left behind somewhere after the first rebuild) I'll test the stat before fitting it.

Dominic
dominic clancy

I have just fitted a new 82 degree status to my car to replace the 8 year old similar one.
Mostly out of curiousity I tested them both together in hot water and whilst they both opened at more or less 82 degrees, I noticed that the new one opened far wider than than the old one.

So I am pleased that I changed it.
Colyn
Colyn Firth

Just to clarify my post, my predictive text decided to change my intended word "stat" for "status"!
Colyn Firth

20c? Any car should run cool at those temperatures. Try idling in city traffic at 45c! That's what I drove through the other day. In case you're wondering, yes it ran hot. 1798cc btw.
Steve Simmons

Steve ...your temp is now striving to get up to the vizard and burgess recommendation...go the whole hog and buy a 88c unit .

I do also recollect reading that changing thermos depending on climate was a mg recommendation.....the higher thermos for colder air temps. ( ie uk summer,winter and during EU referendums)
Neil Ferguson

Steve S

I totally agree with you and I always say in my rantings: 'UK temperate climate'. The truth is, though, that many, many cars in the UK still run unacceptably hot.

In this thread I have been playing around with my car that already runs nice and cool and I have proved to myself that I can control my temperature quite happily with a choice of the appropriate thermostat.

Tried to find some traffic queues yesterday but basically failed. 5 mins was the best I could manage. They all seemed to notice me joining at the back and got a move on! The car behaved just like it does in the garage and the temp stabilised at 178, cycling up and down by perhaps 4 degrees as the stat opened and closed. My impression is that the 7-blade fan works really well at idling rpms.

Steve
Steve Gyles

This thread was discussed between 17/06/2016 and 23/06/2016

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