Temperature guage

Louatlvc · Jul 5, 2016

I'm posting on this thread bc I use my truck daily and can't drive it due to following:
I have 1995 3.0 V6 standard. Just purchased Glow Shift water temperature guage and took day off today to install. Installation involves cutting radiator hose and inserting a spacer that holds an electronic temperature sensor that gets wired to the guage. The idea is that as the coolant heats up it activates the sensor which protrudes into radiator hose and gives reading. After installation, I turned on the ignition and guage went through cycle where the needle goes all the way up then returns to zero. According to tech people this is correct. The problem is that when running the truck the guage did not rise from zero. I ran truck for 20 minutes and stock guage was at normal running temp mid point.
According to tech people at Glow Shift, the insert and sensor should be placed in the radiator hose that does NOT have the thermostat. On my truck this is the lower hose which is where I installed it. The top hose goes to the thermostat.
According to the tech people the only explanation was a bad sensor. They suggested returning it for a new one.
After thinking about it I decided to remove the sensor from the hose insert and test it. I left everything wired as before but this time placed the sensor in boiling water and it worked fine.
When I removed the sensor I had to drain antifreeze again so until I work this out I can't drive the truck. Any ideas why I got reading in boiling water but not when installed?
Any help would be greatly appreciated! Lou

RonD · Jul 5, 2016

Did you ground the insert/sensor?

This is a bung kit that should be similar to what you installed: http://www.autometer.com/1-1-2-radiator-hose-adapter.html

The black wire with that kit is the ground wire, since the bung is hooked to rubber on both ends it is not grounded, and sender/sensor needs a ground.

Also lower rad hose will read 10-15deg cooler than actual hottest coolant temp, which is at the top hose, regardless of thermostats position.

Hot coolant goes out of the engine to the rad on top hose, it travels down the rad and goes back into the engine on the bottom hose.
Most rads cool 10 to 15deg, depending on outside temp and air flow thru the rad.

Louatlvc · Jul 5, 2016

Hey RonD
Thanks for the quick reply. Yes. I grounded the sensor. Do you think I should have installed it on the upper radiator hose that goes to the thermostat? I'm not sure why the directions said to use the NON THERMOSTAT hose. I just followed the directions.

RonD · Jul 5, 2016

Because the temp gauge won't show a high temp until thermostat opens, then it will shoot up fairly fast, probably scares the tourists, lol.
I don't see that as an issue, since point of the gauge is to see operating temp not warm up temp.

If Sender and Gauge are grounded, and the wire between them is good then it will work.

Louatlvc · Jul 6, 2016

I got it working. Looks like it was a grounding problem. Although I grounded it to the frame when I relocated the ground to the neg battery terminal it started working. Interestingly, it's only reading about 150 F when fully warmed up. As you said, I have it mounted to the lower hose which seems to be reading low. I may relocated it to the top hose. Even though there will be a delay until the thermostat opens, I'm thinking I will get a more accurate reading?

RonD · Jul 6, 2016

Good work getting it working

Yes, upper hose will be warmest coolant temp.

If on the upper hose you want bung hole on the side or bottom of upper hose, as that hose loses coolant first if there is a leak, you want sensor to be in contact with fluid not air to get the most accurate temp.

Not sure what new sensors threads are but you could install the new sensor in place of the old sender on the intake manifold, and move the old sender/and its wire to the bung on the lower rad hose, it's gauge doesn't have temp in degrees just "normal" needle position, which would be lower but something you would adjust to as "normal".

There are two temp sensing units on the intake manifold.
2 wire sensor for the computer only
1 wire sender for the temp gauge only

1 wire sender is the one you would move, and since it is only a 1 wire sender you would need to Ground the bung, if bung doesn't have a Ground terminal screw, then you can strip back a wire then place it between rad hose and bung, hose clamp will hold it in place

Adapters are available: http://www.autometer.com/accessories/adapters-fitting-hose.html
Most auto parts stores have a good selection of these adapters.

Louatlvc · Jul 6, 2016

Looks like I did a lot of unnecessary work! I should have researched a bit beforehand and would have bought one of these adapters and connected at the manifold. Oh well - It's been a good learning experience. Thank you again for all your help. Lou

Temperature guage

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