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Temperature Guage Issues
ChrisJ15 - 25/10/15 at 03:07 PM

I put coolant in my Duratec today and was able to run it up to temperature for the first time.

I calibrated the orignal Ford Temp Sender for the Omex ECU (ice cold and boiling water) and fitted Caerbonts Temp Sender with their guage. The sender is housed in one of those aluminium housings you put inline with the hose. Its just outside the housing where the Ford one is.

The problem is that the Caerbont guage is all over the place and nowehere near what the ECU says. The ECU shows it warming up nicely on idle, up to 100deg where the fan comes on.

I thought it may have been an airlock in the housing so removed the sender and then removed the header tank cap so water was flowing out of sender housing then screwed it in again.

Still the same though. When car warms up it is about 20deg behing ECU temp then when ECU temp stabilises at 100 it carries on up past the end of the guage (120)!

Any ideas? Is it better to mount the temp sender housing so the temp sender is pointing down instead of up to make sure it's in contact with coolant?

blakep82 - 25/10/15 at 03:14 PM

I'm going to guess the ford ECU sender is one side of the thermostat, and reading the actual cylinder head temp, and the gauge sender is the wrong side of the thermostat, and reading the hose temp, which will go up when the thermostat is open, and down when it closes

[Edited on 25/10/15 by blakep82]

ChrisJ15 - 25/10/15 at 03:25 PM

The Ford sensor is in the Sensor housing which is on the end of the cylinder head. The Caerbont sensor is in the big hose that comes away from that, as close as possible.

The thermostat is at the other end in the block.

joneh - 25/10/15 at 03:46 PM

Are these gauges 12v or do they need a voltage stabiliser like the smiths ones?

ChrisJ15 - 25/10/15 at 03:54 PM

Doh! Just realised that the housing isnt earthed!

I earthed it temporarily (not sure how I'm going to do this without causing leaks!) but now the guage goes straight off the end of the scale when its cold! I'm guessing its wired incorrectly. Will check and report back.

Very strange that it read anything at all!

[Edited on 25/10/15 by ChrisJ15]

ChrisJ15 - 25/10/15 at 03:57 PM

it was the 12V one.

big-vee-twin - 25/10/15 at 06:43 PM

I have same arrangement in my Duratec the ford sensor at the back of the head has the water flowing past it through the bypass and therefore is more sensitive than the one in the top hose, which starts to work when thermostat opens at 85 degrees and gets flow past it.

ChrisJ15 - 31/10/15 at 05:16 PM

Ive earthed the sender and it still is way out.

You can feel the temperature drop off as you move away from the sensor housing. It doesnt really register anything until the thermostat opens and there is flow.

Ive asked Revotec how big their 1/8 NPT internal thread self sealing jobby is to see if there's room on the other side of sensor housing to fit it.

I see there's an aluminium sensor housing which could be drilled and tapped but no-one seems to sell it new. I only see them on eBay from old Mondeos.

Angel Acevedo - 1/11/15 at 02:50 AM

quote:
Originally posted by ChrisJ15
Ive earthed the sender and it still is way out.

You can feel the temperature drop off as you move away from the sensor housing. It doesnt really register anything until the thermostat opens and there is flow.

Ive asked Revotec how big their 1/8 NPT internal thread self sealing jobby is to see if there's room on the other side of sensor housing to fit it.

I see there's an aluminium sensor housing which could be drilled and tapped but no-one seems to sell it new. I only see them on eBay from old Mondeos.


If sender is on a high spot in the cooling system, there may be an air pocket that goes away once you have flow.
HTH.
AA

ChrisJ15 - 1/11/15 at 09:40 AM

quote:
Originally posted by Angel Acevedo
quote:
Originally posted by ChrisJ15
Ive earthed the sender and it still is way out.

You can feel the temperature drop off as you move away from the sensor housing. It doesnt really register anything until the thermostat opens and there is flow.

Ive asked Revotec how big their 1/8 NPT internal thread self sealing jobby is to see if there's room on the other side of sensor housing to fit it.

I see there's an aluminium sensor housing which could be drilled and tapped but no-one seems to sell it new. I only see them on eBay from old Mondeos.


If sender is on a high spot in the cooling system, there may be an air pocket that goes away once you have flow.
HTH.
AA


Thats a good point. The sensor points upwards and I did wonder about poiting it downwards to increase the chance of it being in contact with water. I'll try that before I do anything drastic.

Pretty sure the water isnt warm where its located though because yuou can feel the lack of temperature on the pipe. Really want the gauge to show what temperature the ECU is getting.

britishtrident - 1/11/15 at 03:33 PM

The temperature sensor output depends on the temperature that surrounds the thermistor with it dosen't matter if air, water or anyting else, it will work point up down or sideways.


A temperature sensor that is not exposed to a constant flow of circulating coolant will always give readings that don't represent the temperature of the coolant at the top of the engine. In other words an in-line temperature sender in the top hose won't work, to give useable readings it needs to to have a flow past it that is not dependand on the thermostat being opened or closed ie an in-line sender needs to be in the by-pass hose.



The above dosen't apply to fan switches which will function without any problem in a top hose.



[Edited on 1/11/15 by britishtrident]