lotus7racer

I have two coolant temperature sensor. The stock sensor screwed behind the head and my option coolant sensor (for my aftermarket gauge) placed in one of the hoses before the thermostat neck (sensing the water temp at the block).

The two sensors has different reading. Silly question: is the stock sensor sensing the water temperature plus the temperature of the head?

My option coolant sensor is placed in the rubber hose sensing just the coolant temperature but not the head.
Could this be the difference of reading?

I'm sure my aftermarket coolant temp is synch with my gauge.
The stock is showing 200 degrees & fan starts, the aftermarket showing 136, 150 degrees. Sensing same coolant temp.

Any thought?

chris_barry

How are you reading the temperature of the stock sensor? Are you connecting your aftermarket gauge to it? The Honda sensor has a different resistance vs temp to most regular temperature sensors.

lotus7racer

When my fan starts, this is the only indication my stock sensor somewhere @ 200 degrees. My stock sensor only connected to the ecu (never touch the wiring). I have no gauge connected to the stock sensor.

The resistance of my extra sensor is sych to my after market gauge.

Back to my question: is the stock sensor which is burried to the head could be the difference as oppose to the other sensor that was installed in the hose?

chris_barry

The radiator fan is normally switched on by the radiator fan switch in the radiator.

The ECU will also switch on the fan if the AC is on, and at certain road speeds. It will also switch it on if the engine is Mega hot as a last resort if the radiator temp sensor isnt working.

The coolant flow in the engine loops around the thermostat to heat the thermostat cartridge. The thermostat blends cooler water from a second "loop" out to the radiator to regulate the temperature. The flow out of the engine into the hoses will generally be lower than that on the inside engine loop.

I would use a radiator fan switch to switch the fans, not the ECU. As for the temp differences, use an infrared temp sensor to check temps in the alloy housings next to where you are measuring.

lotus7racer

Thanks Barry---yep I used an infrared temp sensor to check the temp.
Also, yes I use the radiator switch to initiate my fan at 200 degrees.

I will try to relocate my aftermarket sensor and install in the head instead in the hose loop.

Thanks you.

chris_barry

I put my second temp sensor in the elbow that exits the head where I welded up the heater supply. This is between the hose that loops back to the thermostat and the head so it is should be in the hot loop.

I used a custom calibration on the AEM for the water sensor which I got on S2KI which agrees with what my temperature gauge reads.

lotus7racer

Is that the elbow on the top near the stock coolant sensor?
How did you install the 2nd sensor in the elbow? Did you tap ?

Thanks

f20ckitcar

Lotus7racer,

I am sure speedracer wil answer and give you specifics of where he found a spot for his additional sensor, however in the meantime I located mine as follows:

I found a flat area just below the stock sensor location, a little closer to the block. Here i tapped a hole - to achieve this i removed the entire intake assembly (for access and to clearout swarf in the coolant channel).

Regards
Chris

lotus7racer

Thanks Chris...I will do the same.