Overstated Temp Readings (Despite all new parts)
Discussion
Anyone familiar enough with the 3.0 liter V6 Essex as to why, despite a brand new water temp gauge, new sensor/sending unit, and new voltage regulator (10 volts) all from same gauge supplier, would make the gauge read approximately 20 degrees C above the actual engine temperature? Even the gauge and equipment supplier cannot answer why it would perform as it does. Voltage, or is one of the components bad? The engine is running where it should at approximately 90 C (per two different IR thermometers). But the gauge reads almost 120 C.
Edited by SquashedCat on Wednesday 19th August 23:57
The experts will come along shortly, but in general in such a situation I would start by putting the sensor in a cup of boiling water and check if the gauge reads 100 or 120 degr. In that way you could at least rule out a possibility, namely correct measurement and presence of a hot air pocket.
Then I would measure the voltage at the gauge. New components does not mean functioning components sometimes.
If all that does not solve the mystery, it could only be gauge/sensor incorrect functioning or mismatch or a resistance somewhere in your loom. Good luck!
Then I would measure the voltage at the gauge. New components does not mean functioning components sometimes.
If all that does not solve the mystery, it could only be gauge/sensor incorrect functioning or mismatch or a resistance somewhere in your loom. Good luck!
RCK974K, thank you, your answer seems to make perfect sense. I get the impression this is a rather common issue, hence, I relied on the gauge retailer to provide correct gauge replacement, sender and voltage regulator that actually works correctly together (silly me). So, has anyone figured out what type of water temp sender unit (Ford or someone else that works correctly with a Smith 10V water temp gauge in a 3.0L Essex V6?)
As setup, new sending unit, wired directly to new voltage regulator (10V) with hot wire from battery then wire to gauge, gauge grounded. The old stabilizer is still there, as fuel gauge works fine and does not seem to be directly connected to new voltage regulator. As to vendor, I do not know who specifically the units where purchased from, as garage ordered them from the gauge dealer, but all items are supposed to be correct for the gauges. When garage contacted vendor, they too at a loss for higher gauge read than actual engine temp. The garage did an experiment, added some resistance and the gauge read approx 20 C cooler than actual engine temp, but could not nail the actual temp. Would an adjustable voltage regulator, something that could be adjusted down from 10 volts to achieve right temp reading?
Edited by SquashedCat on Thursday 20th August 13:10
If its any help mine has read 140C for two years once warmed up in the daytime in spring & summer & the engine is still the best part of the TVR 3000M. I got a new sender link from Adrian, got Gadge to help me with various change of meters/ electronic links here in Nottingham, and still no difference , so I gave up.
Always a relief though to get home and find no excessive heat from under the bonnet !
An mgb gt owning mate of mine simply undid his meter it was such a waste of space/ distracting so its not just TVR's.
Always a relief though to get home and find no excessive heat from under the bonnet !
An mgb gt owning mate of mine simply undid his meter it was such a waste of space/ distracting so its not just TVR's.
imho you need a Voltage Stabiliser which is very small and screwed to back of dash near speedo or can be screwed to speedo case. A Voltage Regulator is a black box e.g.Lucas RB 340 or similar to work with a Generator.
I have a Voltage Stabiliser on my 1600M,3000S and Lotus Elan to stabilise 10Volt supply for Fuel and Temp Gauges.
Alan
I have a Voltage Stabiliser on my 1600M,3000S and Lotus Elan to stabilise 10Volt supply for Fuel and Temp Gauges.
Alan
Sorry for confusion of terminology, what I am calling a voltage regulator is in fact the voltage stabilizer, correct one for the gauge 10V and tested by the garage as allowing 10V to the gauge. The fuel gauge is still connected to the old stabilizer, and the new one is only connected to the water temp gauge. This is a classic Smith water temp gauge, anyone have any luck with a sending unit that correctly works with the gauge that fits a Ford Essex? I have been searching on line to find something compatible with the specifications outlined earlier by RCK974X, but I am having trouble finding the operating specs for the sending units. Some units do provide operating characteristics, most do not. Anyway, at least I now have some early warning on potential overheating as the gauge operates in between 110 C and 120 C instead of the 135 C to 140 C range it did before.
I really do not know if the unit is a two or a one VS, as I did not install it, but I can contact the technician who installed it to find out. I can only assume it is a one gauge VS as it is only connected to the water temp gauge and not the fuel gauge, which is still connected to the old unit. How does one tell if it is a one gauge or two gauge VS unit? I can also inquire specifically how he tested the power to the gauge, but he did say that he was getting 10V to the gauge. But he tried using another a fuse? in line to increase the resistance and it was able to lower the temp to a reading approx 20 C below the actual IR reading on the engine temp. But again, he could not get it to read at about 90 C. I was not there when all this work was being installed, unfortunately at my day job. But this is what was relayed to me.
Hi Squashed Cat (great name) I too have had the same problem, I replaced every single component including some of the wiring as I believe the gauge works on resistance. The temperature sender and the electronic voltage stabiliser were from Adrian so I knew they were ok. I bought an infra red temperature gun so I knew everything was ok temperature wise but it still niggles when the gauge is reading so high. In the end, I installed a mechanical gauge in addition to the electric gauge and that never goes above 90 degrees. It is nice to be reassured that you are not going to end your journey in a cloud of steam.
Thank you everyone, greatly appreciate your help. This high water temp reading seems to be such a common problem, should be a relatively easy fix, after you get done pulling out all of your hair in frustration. I am going to try two possible solutions, one is a VDO sending unit that seems to correspond more closely with the resistance levels at various operation temperatures more closely related to the Smiths information provided by RCK974X. And the second solution is his tried and true Triumph 2000 Mk1 series sending unit. I will keep you posted as to the results of using each unit.
a temperature gauge, with its sender mounted somewhere inside the block / head, direclty in contact with the water will show a different temperature than an infrared thermometer.
the infrared reading is usually lower than the "real" temperature.
so your gauge might show the correct temperature, indicating that you have a further (cooling) problem.
i´ve driven cars on the track which heated up to 120degrees (readings on the gauge)but still didnt spit any water.
the infrared reading is usually lower than the "real" temperature.
so your gauge might show the correct temperature, indicating that you have a further (cooling) problem.
i´ve driven cars on the track which heated up to 120degrees (readings on the gauge)but still didnt spit any water.
Edited by GinG15 on Saturday 22 August 12:37
GinG15 said:
a temperature gauge, with its sender mounted somewhere inside the block / head, direclty in contact with the water will show a different temperature than an infrared thermometer.
the infrared reading is usually lower than the "real" temperature.
so your gauge might show the correct temperature, indicating that you have a further (cooling) problem.
i´ve driven cars on the track which heated up to 120degrees (readings on the gauge)but still didnt spit any water.
I hear what you are saying, but would the IR temp reading really be that significantly lower (20 C) than the actual water temp at the sender at operating temperature? We have used two different IR thermometers on the engine, as well as two different techs in two different cities, once when the car was gone over when purchased, and the second by the tech who installed this latest fix, all reported operating temps at approximately 87 to 89 C. So, we are pretty convinced the engine operates at normal specifications and it is voltage issue causing the higher than normal reads. The old gauge and Ford sending unit had the temp at 130C to 140C. This latest fix is slightly better at 120C, but it is just not satisfactory, trying to resolve it so I can have greater confidence in numbers being reported as the current status of the engine. The Essex is a tough engine, but a cooked one does me no good.
the infrared reading is usually lower than the "real" temperature.
so your gauge might show the correct temperature, indicating that you have a further (cooling) problem.
i´ve driven cars on the track which heated up to 120degrees (readings on the gauge)but still didnt spit any water.
I hear what you are saying, but would the IR temp reading really be that significantly lower (20 C) than the actual water temp at the sender at operating temperature? We have used two different IR thermometers on the engine, as well as two different techs in two different cities, once when the car was gone over when purchased, and the second by the tech who installed this latest fix, all reported operating temps at approximately 87 to 89 C. So, we are pretty convinced the engine operates at normal specifications and it is voltage issue causing the higher than normal reads. The old gauge and Ford sending unit had the temp at 130C to 140C. This latest fix is slightly better at 120C, but it is just not satisfactory, trying to resolve it so I can have greater confidence in numbers being reported as the current status of the engine. The Essex is a tough engine, but a cooked one does me no good.
Edited by GinG15 on Saturday 22 August 12:37
Could easily be 20C out. It is not measuring the water temperature, its measuring the surface temperature of whatever you are pointing it at, and even when doing that they are hopelessly inaccurate.....
Have you programmed the correct emissivity level into your thermometer for the surface that you are pointing it at? Does your thermometer even have the facility to do this? Get that bit right and you MAY get a half decent reading of the surface but not the water temperature.
I use these things day in day out and would never trust one to give an accurate temperature reading... They are OK for rough differential temperature measurement on similar surfaces, but if you really want know, either use a pipe temperature sensor and wrap insulation around it so it has a chance of being accurate or, as someone else posted, put the sender into a pot of boiling water and see what the guage reads...
Dave
Have you programmed the correct emissivity level into your thermometer for the surface that you are pointing it at? Does your thermometer even have the facility to do this? Get that bit right and you MAY get a half decent reading of the surface but not the water temperature.
I use these things day in day out and would never trust one to give an accurate temperature reading... They are OK for rough differential temperature measurement on similar surfaces, but if you really want know, either use a pipe temperature sensor and wrap insulation around it so it has a chance of being accurate or, as someone else posted, put the sender into a pot of boiling water and see what the guage reads...
Dave
GPW41 said:
Could easily be 20C out. It is not measuring the water temperature, its measuring the surface temperature of whatever you are pointing it at, and even when doing that they are hopelessly inaccurate.....
Have you programmed the correct emissivity level into your thermometer for the surface that you are pointing it at? Does your thermometer even have the facility to do this? Get that bit right and you MAY get a half decent reading of the surface but not the water temperature.
I use these things day in day out and would never trust one to give an accurate temperature reading... They are OK for rough differential temperature measurement on similar surfaces, but if you really want know, either use a pipe temperature sensor and wrap insulation around it so it has a chance of being accurate or, as someone else posted, put the sender into a pot of boiling water and see what the guage reads...
Dave
Hi Dave, Good to know, will take your advice.
Have you programmed the correct emissivity level into your thermometer for the surface that you are pointing it at? Does your thermometer even have the facility to do this? Get that bit right and you MAY get a half decent reading of the surface but not the water temperature.
I use these things day in day out and would never trust one to give an accurate temperature reading... They are OK for rough differential temperature measurement on similar surfaces, but if you really want know, either use a pipe temperature sensor and wrap insulation around it so it has a chance of being accurate or, as someone else posted, put the sender into a pot of boiling water and see what the guage reads...
Dave
Hi Dave, Good to know, will take your advice.
imo 20degrees difference is not unusual.
IR is measuring on an external surface, heated up by the cooling medium. often at the cooling hoses or the upper raiator chamber
the gauge´s sender is measuring directly the cooling medium, surplus its mounted inside the engine.
for example: if you use the IR on a black cooling hose it will show you some different values than on a yellow one.
IR is measuring on an external surface, heated up by the cooling medium. often at the cooling hoses or the upper raiator chamber
the gauge´s sender is measuring directly the cooling medium, surplus its mounted inside the engine.
for example: if you use the IR on a black cooling hose it will show you some different values than on a yellow one.
Adrian@ said:
As I have said previously..an IR temp gauge at 8.91UKP inc postage!!! is the best piece of kit you will ever own for working on your classic car...
Adrian@
Absolutely agree. Thats why mine gets used very frequently, but not on cars unfortunately. Adrian@
Just need to understand how it works and what it is doing so as to not place too much emphasis on the "actual" temperature reading.
A thermal camera is a rather useful piece of kit as well, but unfortunately they are not available for 9 quid....
Dave
RCK974X said:
Found the part number from my archives - Intermotor 52910. It's threaded with a 1/8" BSP I think, so chances are reasonable it will fit in Essex.
The SW sender is almost the same as Smiths too - seems to be an ad hoc standard !
I did a study of gauges and their current flow against needle position, and did a few temp points on senders and fuel senders too, for Ford, BL, and SW (280 wedge) for kits etc. - can post these if it helps, just ask.
RCK974X, Thank you, you are the man! The Intermotor 52910 works great! My brand new Smiths gauge and voltage stabilizer, works well with your recommended sending unit. The gauge is now reading approximately 100 C, much better than 120 C. Sorry it took so long to post the results, but the sending unit had to be ordered from the UK to US, and then had wait until the weekend to be installed. I was concerned at first it took a while for temp to jump above 60 C. But then stayed right at 100 C. The IR thermometer reading 97 to 98 C. Pretty close correlation. Again, thank you for your research to a very vexing, pain in the posterior problem. And thank you PM's for your very practical suggestions and approaches to solving the issue.The SW sender is almost the same as Smiths too - seems to be an ad hoc standard !
I did a study of gauges and their current flow against needle position, and did a few temp points on senders and fuel senders too, for Ford, BL, and SW (280 wedge) for kits etc. - can post these if it helps, just ask.
Edited by RCK974X on Friday 21st August 00:51
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