Temp gauge reading

ducati dad

Still faffing about with the 851/996 project... Fires up and runs OK but the temp gauge only gets to 40c very slowly and will sit there even when the fan kicks in. The engine is a ST4s and the standard water sensor is WTS09, even replacing with a new sensor it reads the same. The gauge is the standard 40c- 120c. Should it be wired differently for an analogue gauge?

griff851

There are 2 types of standard temp sensors, blue one and black ones. They have different resistance values.

ducati dad

Hi Griff, I was going by the code stamped on the sensor, WTS09.. Would there be different values even with the same code?..

Mr.R

Hi Mick,

When I stripped a 916 motor to build my 851/916, I thought I'd use the newer sensors from the lower mileage 916 as they all looked similar.
But the temp gauge read incorrectly, so I swapped it back with the OEM 851 item and all was good again.

Steve R

griff851

Hi Mick one would assume the same pt no would have the same values. Unfortunately i did the exact same thing as Steve.

freqrider

What matters most, I would imagine, is not what the gauge is reading, but what the ECU is reading. The ECU monitors temperature to adjust air/fuel ratio and spark advance. If you are swapping engines and ECUs and such, I would use the proper temp sensor for your engine/ecu and swap the guage to match the sensor, or the ecu might not be getting the proper information!

freqrider

freqrider wroteWhat matters most, I would imagine, is not what the gauge is reading, but what the ECU is reading. The ECU monitors temperature to adjust air/fuel ratio and spark advance. If you are swapping engines and ECUs and such, I would use the proper temp sensor for your engine/ecu and swap the guage to match the sensor, or the ecu might not be getting the proper information!

Oh, I just remembered, there are two temp sensors! Lol ^ Nevermind!

ducati dad

Hi freq, apart from the ST4s engine, I've used the ST4s ecu and wiring loom. The sensor in the vertical cylinder feeds the ecu which then switches the fan on, and the hori sensor feeds the gauge. The sensors are the original ones. On the ST4s the gauge is digital so somewhere the signal from the sensor is converted [ I think], so I assumed that if the signal from the sensor was taken straight to the analogue gauge, it would read OK. I'm sure it'll get sorted in the end..😳

BARONROJO

I have an ST4S engine on my bike with its own sensors and the gauge read an abnormaly high temperature. As I have a 59 ECU on the bike I used a potentiometer to make the dial match the ECU reading and it works perfect!