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Best Answer Captain Mainwaring , 07 August 2013 - 01:45 AM

Hey guys, just a quick one: I took he mini for a short drive yesterday and then I took the rad cap off and put a temp sensor in the top of the rad, the temp read 90 degrees and the gauge inside the car was just below he red line. my question is: what is the normal running temp?

 

 

You shouldn't have taken the cap off, though in this case it doesn't matter, the car wasn't boiling. You have however answered your own question and solved your own problem - a car isn't in the red at 90C :-)

 

anything between 82 and 92 degs is quite normal temp

in the cylinder head temp will be slightly higher, so i'd expect the gauge reading a bit higher, when temp outside gets above 30° minis tend to run quite hot, but if temp goes quickly above 95-98 degs while driving, then you have a problem somewhere

 

Well not really once you are above the stat opening temperature. 

The circ water temp will increase once the balancing point of the cooling system is reached - given a certain ambient temp with the engine under a certain operating condition, the circ cooling water temp will increase until their is sufficient differential in the circ water temp and the ambient air temp to effect a change in the heat balance and allow heat energy to flow from the cooling system to the surrounding air. Heat transfer is expressed as W/(mK) so a cooling system water/air will loose 1/(273+new ambient temp-original ambient temp) *100% efficiency for a given change - it won't suddenly get worse at 30C.

 

I don't  reckon an engine is excessively hot at 90C and the gauge certainly shouldn't be in the red - unfortunately these are hardly calibrated instrumentation and I think there may be a huge difference between calibration of gauge head units and PT100's (i'm guessing that they are 100's)

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#16 Rog46

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Posted 21 July 2013 - 08:09 PM

After the flush put the antifreeze in sooner rather than later because 1. If you leave it you could forget it and 2. It contains a corrosion inhibitor.

#17 Pog49

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Posted 06 August 2013 - 01:38 PM

Hey guys, just a quick one: I took he mini for a short drive yesterday and then I took the rad cap off and put a temp sensor in the top of the rad, the temp read 90 degrees and the gauge inside the car was just below he red line. my question is: what is the normal running temp?



#18 Frisco

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Posted 06 August 2013 - 02:27 PM

Don't waste money on antifreeze at the moment - plenty time for that when summer blows away.....  

 

 

Well that's terrible advise.

Coolant/antifreeze has corrosion inhibitors in it so as well as stopping things from freezing it stops the inside of the engine from rusting which causes silt and the silt has a habbit of blocking rads and heater cores.



#19 jaydee

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Posted 06 August 2013 - 02:27 PM

anything between 82 and 92 degs is quite normal temp

in the cylinder head temp will be slightly higher, so i'd expect the gauge reading a bit higher, when temp outside gets above 30° minis tend to run quite hot, but if temp goes quickly above 95-98 degs while driving, then you have a problem somewhere



#20 Rog46

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Posted 06 August 2013 - 03:41 PM

Put the antifreeze in straightaway. It contains a corrosion inhibitor as well. Everything corrodes fast enough as it is , do your best to slow it down!

#21 DILLIGAF

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Posted 06 August 2013 - 11:13 PM

Certainly good advice - but don't mess around borrowing one - just buy a new one. Also check the seat inside the cap.....You can pressure test a system by filling it up and the putting a footpump on the rad overflow and clamping the schrader shut over it - it's close enough to hold pressure.

 

 

Bring it up to 15 to 20 psi and leave it...see what happens.

 

 

 

LOL Classic.............



#22 Captain Mainwaring

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Posted 07 August 2013 - 01:20 AM

 

Certainly good advice - but don't mess around borrowing one - just buy a new one. Also check the seat inside the cap.....You can pressure test a system by filling it up and the putting a footpump on the rad overflow and clamping the schrader shut over it - it's close enough to hold pressure.

 

 

Bring it up to 15 to 20 psi and leave it...see what happens.

 

 

 

LOL Classic.............

 

 

What's "LOL Classic"? - it works - it's an easy way of pressurizing a cooling system - moreover the cap has a NRV/vacuum breaker built in so it can be left under pressure.

 

Have you nothing better to add to the discussion? Nearly 3500 posts and this is the best comment you can make?

Please don't derail a thread where an OP is looking for advice, go play on the "my cooper brake pedal fixes all braking system problems" thread .


Edited by Captain Mainwaring, 07 August 2013 - 01:23 AM.


#23 Captain Mainwaring

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Posted 07 August 2013 - 01:45 AM   Best Answer

Hey guys, just a quick one: I took he mini for a short drive yesterday and then I took the rad cap off and put a temp sensor in the top of the rad, the temp read 90 degrees and the gauge inside the car was just below he red line. my question is: what is the normal running temp?

 

 

You shouldn't have taken the cap off, though in this case it doesn't matter, the car wasn't boiling. You have however answered your own question and solved your own problem - a car isn't in the red at 90C :-)

 

anything between 82 and 92 degs is quite normal temp

in the cylinder head temp will be slightly higher, so i'd expect the gauge reading a bit higher, when temp outside gets above 30° minis tend to run quite hot, but if temp goes quickly above 95-98 degs while driving, then you have a problem somewhere

 

Well not really once you are above the stat opening temperature. 

The circ water temp will increase once the balancing point of the cooling system is reached - given a certain ambient temp with the engine under a certain operating condition, the circ cooling water temp will increase until their is sufficient differential in the circ water temp and the ambient air temp to effect a change in the heat balance and allow heat energy to flow from the cooling system to the surrounding air. Heat transfer is expressed as W/(mK) so a cooling system water/air will loose 1/(273+new ambient temp-original ambient temp) *100% efficiency for a given change - it won't suddenly get worse at 30C.

 

I don't  reckon an engine is excessively hot at 90C and the gauge certainly shouldn't be in the red - unfortunately these are hardly calibrated instrumentation and I think there may be a huge difference between calibration of gauge head units and PT100's (i'm guessing that they are 100's)



#24 jmmini

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Posted 07 August 2013 - 01:48 AM

What I have recently dine is fit one if those £20 eBay radiator fans cable tied it to the inner wing, and wired it to the switch, my engine is far from standard and also have a heater matrix from an Audi a3 by the grille in series to the original rad. But when thrashing the car around the leccy fan keeps the temperature at 1/2-3/4 and never exceeds this.

#25 Yoda

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Posted 07 August 2013 - 05:00 AM

Hey guys, just a quick one: I took he mini for a short drive yesterday and then I took the rad cap off and put a temp sensor in the top of the rad, the temp read 90 degrees and the gauge inside the car was just below he red line. my question is: what is the normal running temp?

 

So, I assume that you used a spare mini temp sender or was it some other type of thermometer? If it was a spare sender, then fit it to the car and see what the gauge reads? it does look like the one on your car is going too low resistance or short once warmed up.



#26 Frisco

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Posted 07 August 2013 - 07:09 AM

 

 

Certainly good advice - but don't mess around borrowing one - just buy a new one. Also check the seat inside the cap.....You can pressure test a system by filling it up and the putting a footpump on the rad overflow and clamping the schrader shut over it - it's close enough to hold pressure.

 

 

Bring it up to 15 to 20 psi and leave it...see what happens.

 

 

 

LOL Classic.............

 

 

What's "LOL Classic"? - it works - it's an easy way of pressurizing a cooling system - moreover the cap has a NRV/vacuum breaker built in so it can be left under pressure.

 

Have you nothing better to add to the discussion? Nearly 3500 posts and this is the best comment you can make?

Please don't derail a thread where an OP is looking for advice, go play on the "my cooper brake pedal fixes all braking system problems" thread .

 

 

How does it work?

 

The top of the rad cap doesn't seal so if you lift the seat it will just leak out to atmosphere


Edited by Frisco, 07 August 2013 - 07:11 AM.


#27 Yoda

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Posted 07 August 2013 - 07:14 AM

I think you will find on most Mini rad caps there is a drawback valve in the centre that will allow air in ( normally used for overflow bottle draw back on vacuum when cooling down to keep system filled ) I am not sure if all aftermarket caps have this feature though plus many systems have a sealed or open cap for pressurised expansion bottles.


Edited by Yoda, 07 August 2013 - 07:14 AM.


#28 Frisco

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Posted 07 August 2013 - 07:28 AM

Yes but the top of the cap isn't sealed



#29 DILLIGAF

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Posted 07 August 2013 - 09:25 AM

 

 

Certainly good advice - but don't mess around borrowing one - just buy a new one. Also check the seat inside the cap.....You can pressure test a system by filling it up and the putting a footpump on the rad overflow and clamping the schrader shut over it - it's close enough to hold pressure.

 

 

Bring it up to 15 to 20 psi and leave it...see what happens.

 

 

 

LOL Classic.............

 

 

What's "LOL Classic"? - it works - it's an easy way of pressurizing a cooling system - moreover the cap has a NRV/vacuum breaker built in so it can be left under pressure.

 

Have you nothing better to add to the discussion? Nearly 3500 posts and this is the best comment you can make?

Please don't derail a thread where an OP is looking for advice, go play on the "my cooper brake pedal fixes all braking system problems" thread .

 

 

Whats classic is the crap your talking..........

 

To do this you'd need to fit a blanking cap to the rad..............

 

ffs you can't put pressure behind a seal and expect it to pressurise the cooling system thats on the otherside of the seal.........

 

Remind me again what did you claim your job was in another post, something to do with fluids/hydraulics ?



#30 lrostoke

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Posted 07 August 2013 - 09:34 AM

May of missed it but as anybody mentioned it may be the gauge / voltage regulator ??

 

As it got the standard clocks, any changes.

 

My sisters was showing over heating problems turned out to be the smiths gauge wasn't wired through the voltage regulator, bit of rewiring and now it reads normal like it should.







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