I recently installed a autometer temp gauge/sender in the factory pipe thread hole located on the side of the front housing that has the radiator cap on it. I noticed several threads that recommended drilling/tapping the housing adjacent to the coolant level sensor but I assumed the pipe thread plugs were in the housing for a purpose?

I been trying to get a handle on the temps of my recently rebuilt FD which feels like it is running extremely hot. First off the gauge doesn't register until the thermostat opens up...which I assume is because it is located outside the thermostat but even after it opens I have yet to see temps get above 195 deg even with a BLitz FMIC and no underbelly pan. I am now questioning whether this location is giving me accurate readins???? Is there any documented use of this factory plug...the location would appear to capture water temps as it is leaving the block but is there any pros/cons from this location other than getting readings only after Temp gauge opens up?

Thanks,

Chris

 

though i cant say 100% your readings are acurate...mine is virtually in the same spot and my readings match what I see on my powerFC.....i see 170 to 180 with just driving (ive ducted my entire fmic and radiator)...

But the spot you have tapped is fine and will work with out a problem, many use it...I actually tapped just a little to the lower right of the stock temp sender...

 

Are you tapping at the top most surface next to the radiator cap? If so, you may be seeing air being trapped near the radiator cap and therefore no temp reading until radiator cap opens up.

To ensure that the sender is bathed in coolant, I installed my sender on the flat portion right above the water level sensor.

 

I guess I wasn't too clear in my first post.....but I am not tapping anything at all. I am using one of two existing holes that are filled with a plug from the factory. The main reason I am posting is due to the fact that I consistently see threads about drilling/tapping, putting it in the water hose etc, but this seems like an obvious place to mount a temp sensor and in fact it bolts right in, no drill/tap needed. Just wondering why no one else is using this location and if it had anything to do with inaccurate temp readings.

Thanks for the input,

Chris

 

Pull the cap off your thermostat housing. See that small hole towards the rear. That hole feeds the chamber that has those plugs in it. The outlet of the chamber is the fitting that feeds the AST. If you have done an AST elimination, then the coolant (if any) in that chamber is stagnant. If you still have an AST, then the flow is rather limited.

 

Ahh, I was wondering what that hole was there for. I have eliminated the AST so I am probably not getting the real accurate temps. Thanks for the reply

 

clayne wrote an awesome thread about tapping

https://www.rx7club.com/3rd-gen-archives-73/water-temperature-sensor-how-tap-install-247152/

 

Yeah, read all the drill/tap thread, I still wonder why mazda decided to put those plugs there
in the first place....just happen to fit my autometer gauge sensor perfectly. I may try a diff location to see what the difference is in temps.

thanks,

Chris

 

hmmm i put mine behind the water pump, kinda under the UIM.... i read between 190-210F... once it reaches 210F the fans kick in and temps drop to 190. this is Highway driving... but that is normal...... i have a fully stock car with only intake.... so im guessing DP, Radiator... etc.. mods. will drop these.... but i dont see no problem with the 195F , isnt 235+overheating (hot) temps?? correct me if im wrong.

also i have the DEFI LINK set up

 

If you don't want to drill and tap anything, get a greddy 38mm radiator hose adapter for around $30. I put mine in the radiator hose just after the exit from the engine. It works very nicely ........... once the t-stat opens.