silverrotor.....from all the posts i've been reading lately on the subject, it seems that the temp sensor under the oil pressure sender is soley used by the stock coolant gauge. The ECU reads off the thermosensor which is located on the back of the coolant neck. This is just what I've read though.

Also, I went and looked at my coolant neck right after the thermostat and mine doesn't look anything like anybody else's i've seen posted on here so far. Most people's are silver with that very convient bump on it to tap rite into. My neck is black and doesn't have that bump on it. I will try to get a pick of it later. I'm still thinking of using the stock location for my greddy gauge since it will screw right in, but I would like to have my stock gauge working also.

 

If your gauge is to be accurate at all the sensor will not detect the temperature of the housing and will only actually read the temperature at the tip of the sensor. By the time the stationary water in the housing is heat soaked to read an alarming temperature the water in the block is way too hot and is probably already doing damage. It has nothing to do with air cooling the housing it has everything to do with the amount of water stuck in the block reaching a dangerious temperature much quicker than the water outside of the thermostat.

If you think your way is just as accurate then I challenge you to block off your thermostat and run it until your gauge with a sensor mounted above the thermostat reads 210 degrees.

 

the brass of the sending unit will still conduct heat. I challenge you to actually think about what you just said to me...

Where does the heat in the coolant come from? It sure as **** isn't from the water circulating around catching all of it before any of it makes its way into the BLOCK.

I'd even go as far as to say that the temperature of the water pump housing is within 10 degrees of the temp at the filler neck. If I had a infrared temp guage I'd test that theory and post my findings.

 

I DID. With an infrared thermometer. And your findings are exactly correct. With the IR pointed at the stud on the water pump, it read about 200 degreesF at idle, whereas the water pump housing read 190 degreesF, the filler neck read like 170 degreesF and the rad read about 160 degF. These are approximate values as far as i remmeber.

 

Ideally you would want the sensor between the block and the thermostat. I used one of the sensors on the water pump while i had the stock computer, I forgot which one, but your shop manual tells which one doesn't go to the ECU. I have a Haltech now, so it's all good. TO actually think that heat soak through the metal and coolant is good enough is crazy. Your water seals ARE MADE OF RUBBER. I shouldn't have to explain how fragile they are. ON my next rebuild I'm actually going to tap the front houising on the driver side, above where the A/C condenser would have gone. It doesn't get any closer to the block than that. OH and not all of us have a metal filler neck. Some of us have S5's.

 

Yup I have an s5, and i guess i'm stuck with tapping my water pump. Besides, its the only spot with thick enough metal.

Now my question is, would i have to pull the water pump to drill/tap it, or can i just stick a tack cloth in to catch the shavings?

Thanks
-Ross

 

I would deff pull the pump to tap it. I would not risk any metal shavings falling in the motor.