Originally Posted by
shack
The TD5 stock coolant sensor measures coolant, the only time it measures head temperature only, is when you have run out of coolant, and then it will do it very poorly indeed.
The head temp will be different to block temp in almost all situations, and pretty much always significantly hotter than the block.
The coolant going past the stock sensor will be the hottest coolant in the system(at operating temp of course).
A quick test with an uncalibrated IR temp gun shows about 10°temp difference across the top of the radiator.... YMMV.
Wills start with the test.
The calibration is not so important as to the delta, that is if only one gun is used of course, using two is a different story. Was surprised when I originally surmised the theoretical figure of it only being around 10C drop across the radiator (hence my questioning) and although not Nobel winning science, your figure backs that up somewhat. I don't expect you are the sort of person to have a clogged and inefficient radiator lol.
Prior to this as not having thought or had figures surrounding operational aspects of the radiator, would have suggested at least 20, maybe 30 and even 40C as being reasonable. It still doesn't sit entirely comfortably with me and sounds rather inefficient even. But even 50% more and it is still less than I would have thought before this.
Though there may be a temp differential from the block outlet to the top of the radiator this is going to be minimal at most. More importantly it would not show coolant temps at the radiator inlet higher than the head as I have found, just doesn't make sense.
If it was the case, the physical thermostat would not operate for 90% of its life when measured against peoples reported Nanocom readings. It goes against what I am finding and what DC assert that the temps being shown by the TD5 sensor are not coolant temps and my findings are its actually 10-15C lower. For either, for the thermostat to be working regularly, the efficiency of the radiator would actually be less than this again!
Even with the temps I am seeing of mid 90's on the EWPC the thermostat is not in play as much as expected with a 10C drop across the radiator. There will be changes to this baseline of course due to the air velocity and humidity etc.
As a point again with the use of bolt on sensors, the Engine Guard website says
" we have reliably demonstrated that if an engine has a sudden loss of coolant, head temperature will start to rise within 20 seconds"
this is not immediate in any sense of the word. It talks further of setting the temps above the "2 – 5 degrees above the normal highest operating temperature" , pretty sound advice. I have put in an order for one as firstly to test the radiator and will move it on to the Auto and Transfer case once I have gotten the information. Looking to simply put the sensors under the coolant hoses in and out for testing purposes.
2004 Discovery 2a TD5 Auto Aspen Green AKA Robin
2000 Discovery 2 TD5 Auto Alverston Red AKA Edward
1997 Discovery 1 TDi Manual White - Gone but not forgotten
1994 Discovery 1 V8 Auto - Gone once it consumed half the worlds resource of oil
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