water temp too low, bad reading location?

[EMWHYR0HEN]

I installed an Autometer water temp gauge and screwed it onto a brass "T" which I then spliced into the heater hose that goes from the engine block to the heater core. Heres a picture :

 

 

No leaks, so took it for a spin and it slowly got up to 75 degrees Cel. ( 167 F) . Just after that the temp went straight back down to 60 cel. which is the lowest the gauge goes . Well I found out my thermostat opens at 76.5 deg. C so that sounds right. However, after the thermostat opened the temp woudnt go past 60 C , and thats with me keeping the RPM's up high in triffic, and no mechanical fan or the electric fan running.

 

popped the hood and noticed that the hose i put the sensor on was slightly cooler than the other heater hose. Doh! so the hose i put the sensor on was the water after hitting the heater core. switch it up and got the same results.

 

So, do you guys think that I put the sensor in an insufficient place to read water temp? If so, where should i place it? It seams im kind of limited because the autometer fitting is 3/8'' , which is fairly big compared to the small metric fittings all over the engine.

 

Or could it be that my radiator is just over kill? its a 24 x 19 x 3'' double pass.

 

 

 

 

It just raises the question if its unsafe to run the engine below operating temps.

[mom'sZ]

I read this thread this morning and I see no one has replied yet, so maybe I can jump start the discussion. In my opinion, in the heater hose is not a good place to check the water temp. From your pictures, it looks like you're not running the stock L6 so I can't be more specific then to say some where into a water jacket directly on the engine. Maybe the thermostat housing or something. Where was the original?

As for the new radiator being "overkill", so long as your thermostat is working correctly there should not be a problem.

[JMortensen]

I've got mine installed in the thermostat housing. Putting it in the heater hose would only give you a correct reading if the heater was on. If the heater valve is closed then there isn't any flow going past the sensor. I don't remember if the upper or lower hose is the return hose, but if you have the sensor in the return hose then you're measuring the temperature after the heater core has taken some heat out of the system too.

[veritech-z]

i don't know how the RB25 is set up, but don't most engines read the coolant temp at the cylinder head? I know the saturns do, and my l28e has a sensor for that in the back of the head. I put my gauge sensor in the thermostat housing which is in the head on the z.

[Lewis Maudlin]

I think you will have adverse effects from running your car too cool. The more heat, the more power to a certain extent.

 

It sounds like your thermostat is not closing after opening. If it opens at 76.5, it should close when it cools then heat back up and open.

[EMWHYR0HEN]

Thanks guys, I didnt know that water/ coolant only passes through the heater core only if the heater was on. I thought its always passing, and when you turn on the heat it just blows air through the core, into the cabin.

 

Ok, well now i have to figure out how im going to mount it onto, or somewhere near the thermostat.

 

anyone know where i can get those radiator hoses that have fittings of some kind on them?

 

any sugestions?

[EMWHYR0HEN]

Hah, I tried it out and my temp gauge read 70 de. C then i turned on my heater and it jumped to 80 right away. Im an Idiot