Water temp gauge sensor placement.

[Sonic31]

I've done quite a few searches but I never really found a solid answer.

From my searches I have come to the conclusion that I could just put it in the coolant line after the thermostat. But there is some debate about the effectiveness of the sensor when placed after the thermostat.

Another option is to tap into the area where the factory sensor is. But that is just not gonna happen.

The option I like is either tapping the line that exits the throttle body, or the line that exists after the factory sensor.

Can someone please confirm the best location.

Thanks!

[Nick]

i'm not sure about the difficulty, but aren't these sensors installed in the rad?

[Sonic31]

Not that I have read to this point.

My understanding is that you need the sensor to be close to the block so that I can get an accurate reading of the coolant temp while it is in the block.

In addition since the rads purpose is to cool the coolant, the reading would not be an accurate reading of what is occurring within the engine itself.

[silverstarmazda]

then that places the temp gauge somewhere in the upstream of the system... it screws into the block

here you go:
http://www.mazda3forums.com/showthread.php?t=329537&page=2

[Sonic31]

Sorry I wasn't horribly clear in my OP.

I'm looking to install an aftermarket one as a sending unit for a gauge in my car.

I've seen that thread before, and while it's a good resource for replacing the OEM sensor it doesn't quite give me what I need.

Essentially I need to find out the best possible hose to attach my sender to (using a brass "t").

[silverstarmazda]

arnt there adapters that fit into the coolant hose? basically a small pipe the same diameter as the coolant hose. but with a threaded hole on the side for the sensor. i would attach it to the "inlet" of the radiator hose. that way your reading the hot coolant before it passes through the rad.

like one of these:
http://www.ebay.com/itm/38mm-WATER-TEMP-GAUGE-JOINT-PIPE-RADIATOR-ADAPTER-w-CLAMPS-COMPLETED-KIT-1-/390464531480?ru=http://search.ebay.com:80/390464531480_W0QQfviZ1

not sure how others here have installed it on theyre 3's. but ive done a couple like this and have good results

[Sonic31]

I know about those adapters, however, while that hose is the easiest to access, it is after the thermostat.

The issue with this is that I have read on several forums people having trouble getting a good reading from that location.

I am looking for the best location that occurs before the thermostat, reading coolant that is flowing from as close to the block as possible, so I can get a solid reading about temps inside the engine.

Also I would have to order that adapter in and I can build my own version of it for less using parts from Home Depot.

However until I know the hose (and thus the inside diameter) I'll be using I don't know what size fittings to use.

[silverstarmazda]

you might as well tap into the engine block itself to get the most direct reading.

[Sonic31]

While that is an option, it's not one that I am willing to take. Too much chance for something to go wrong, especially with my experience level.

There has to be a hose coming out of the block somewhere before the thermostat that I can tap into.

[silverstarmazda]

did you try the throttle body coolant line?

[Sonic31]

That was one I was looking at as an option. I know that hot coolant flows through the TB, and I thought of putting the sensor in the outlet side tube.

One thing that I was looking for, and having a hard time finding, is a diagram of how coolant flows through the 2.3L engine.

I think between studying that and talking here, we could figure it out :).

[silverstarmazda]

if i remember the coolant flows in a "clockwise" direction. the thermostat position also backs up that theory. so the coolant will be coming out hot on the right side of the engine.

[Sonic31]

http://demo.saleepc.ru/mazda/parts/eur/A1/AEBA11/C2/1500BA

Found this, which I think is the 2.3L engine, any idea which hose outta all of these would be the best one?

I am thinking 13-681A. Looks like it's the hose coming out after the factory water temp sensor.