Coolant and Oil Temp Sensor

[Zeus51]

I know this is covered before. I guess I’m looking for current opinions.

Where’s the best locations to add a coolant and oil temp sensor while keeping the dummy lights intact?
For coolant:
Crossover Manifold?
Water pump?
Is there somewhere that will give me an exact coolant temp pre-radiator? Or should I not even be considering pre-radiator?

For oil:
Can I add a sensor just above the oil filter where the stud is located at the oil filter housing?
Is there a better location?

 

[Barrman]

There is a pressurized oil port above the oil filter and oil cooler lines. It has a square 1/4 NPT plug in it. That plug takes a square 1/4” tool. A 1/4” socket extension will fit just long enough to probably round it out. There is a Snap-On tool made just for it. Great place for oil temp. Or turbo oil feed.

The coolant crossover pipe will be the most balanced temp location.

 

[Zeus51]

There is a pressurized oil port above the oil filter and oil cooler lines. It has a square 1/4 NPT plug in it. That plug takes a square 1/4” tool. A 1/4” socket extension will fit just long enough to probably round it out. There is a Snap-On tool made just for it. Great place for oil temp. Or turbo oil feed.

The coolant crossover pipe will be the most balanced temp location.

thanks! I’ll have to find that tool somewhere. Another question about coolant, does the heater core get constant flow from the radiator? Meaning, could I add a tee connection where the heater core hose takes off from the coolant crossover pipe to allow a connection for the coolant temp sensor? Wouldn’t that be the same as tapping directly into the coolant crossover pipe?

 

[chevymike]

I used a HUMVEE crossover tube to add coolant sensor.

 

[Barrman]

Coolant ports are all over the 6.2 engine.

Each head has one at one end. Pass rear (Cold start/fast idle inhibit switch) and drivers forward (Idiot light) past the last exhaust port on each side.

The cross over block off plates at the rear of both heads can be used. Stock CUCV uses the drivers side one for glow plug control sensing. The passenger side is just blocked off with nothing there.

Yes, the heater is constant flow of coolant so it could be T'ed into. As posted above a HMWWV cross over pipe has the temperature sensor mount already threaded in.

 

[cucvrus]

I always used the coolant passage on the right rear head. I just sourced a left head sensor and removed the sensor install a brass fitting to accept the coolant temperature sensor for the gauge. That thing is real close to the instrument cluster so the manual gauge harness must be pretty short to avoid kinks in the capillary. I used an electronic gauge. Good Luck. Be Safe.

 

[Zeus51]

Coolant ports are all over the 6.2 engine.

Each head has one at one end. Pass rear (Cold start/fast idle inhibit switch) and drivers forward (Idiot light) past the last exhaust port on each side.

The cross over block off plates at the rear of both heads can be used. Stock CUCV uses the drivers side one for glow plug control sensing. The passenger side is just blocked off with nothing there.

Yes, the heater is constant flow of coolant so it could be T'ed into. As posted above a HMWWV cross over pipe has the temperature sensor mount already threaded in.

I’m still trying to decide where I’m going to place the sensors but I’ve been looking through the parts manual and I’m trying to figure out what sensor is drivers side rear behind the sensor with two wires? Is the sensor in the pic that has one orange wire the sensor that controls the wait light?

 

[Sharecropper]

I’m still trying to decide where I’m going to place the sensors but I’ve been looking through the parts manual and I’m trying to figure out what sensor is drivers side rear behind the sensor with two wires? Is the sensor in the pic that has one orange wire the sensor that controls the wait light?

The sensor with the 2 wires is the glow plug controller sensor. The big thing over behind the head is the oil pressure idiot lite switch. Leave the glow plug switch alone, it is required to operate the controller card correctly. You could install a temperature gauge sensor directly across in the same location on the passenger side head. You will need a GM 14028949 coolant outlet cover and gasket. These are normally available on EBay and I have occasionally noticed one on Amazon of all places. The temperature gauge sensor will screw straight into 14028949 with a bushing.
Regarding the oil pressure gauge sensor, what I did was go to the hardware store and get a 1/4” NPT 45- degree brass street-L and a 4” brass nipple, and relocate the sensor above the back of the head so you can get to it without using a mirror. Then get/ put a 1/4” brass Tee on top of the nipple. Install the idiot lite sensor in one leg of the Tee and the gauge sensor in the other. I’ll post a photo of my setup when I get back to my office tomorrow.

 

[Zeus51]

The sensor with the 2 wires is the glow plug controller sensor. The big thing over behind the head is the oil pressure idiot lite switch. Leave the glow plug switch alone, it is required to operate the controller card correctly. You could install a temperature gauge sensor directly across in the same location on the passenger side head. You will need a GM 14028949 coolant outlet cover and gasket. the oil pressure gauge sensor, what I did was go to the hardware store and get a 1/4” NPT 45- degree brass street-L and a 4” brass nipple, and relocate the sensor above the back of the head so you can get to it without using a mirror. Then get/ put a 1/4” brass Tee on top of the nipple. Install the idiot lite sensor in one leg of the Tee and the gauge sensor in the other. I’ll post a photo of my setup when I get back to my office tomorrow.

This may be a dumb question, but the temp gauge sensor you reference that would be across from the glow plug control sensor on the passenger side: if I put a temp sensor there, would it be coolant sensor or oil temperature?
Also, what is the sensor with the single orange wire in the pic?

 

[cruzer747]

This may be a dumb question, but the temp gauge sensor you reference that would be across from the glow plug control sensor on the passenger side: if I put a temp sensor there, would it be coolant sensor or oil temperature?
Also, what is the sensor with the single orange wire in the pic?

I think you are misreading what he said.... basically across from the GP sensor on the other head there is a coolant block off plate. Nothing to thread into. The part# is for a plate with threads. This goes into the coolant. You would put a coolant temp sensor in it.

As for the oil temp... making clear it is Temperature and not pressure you are after, 1st reply Barrman tells you the best spot there. If you just wanted oil pressure, a tee under the oil dummy light switch is easy and what I did as well.

 

[Zeus51]

I think you are misreading what he said.... basically across from the GP sensor on the other head there is a coolant block off plate. Nothing to thread into. The part# is for a plate with threads. This goes into the coolant. You would put a coolant temp sensor in it.

As for the oil temp... making clear it is Temperature and not pressure you are after, 1st reply Barrman tells you the best spot there. If you just wanted oil pressure, a tee under the oil dummy light switch is easy and what I did as well.

Thank you for the clarification. I understand now. I pulled the plug by the oil filter housing. I need to get a reducer for the temperature gauge. Does 1/4" describe the square head or is it the thread also? Once I pulled it, I can't get the plug to screw into my thread identifier. I guess what I'm asking is what size threads are on the plug?

edited to add the pic

 

[cucvrus]

I think (I know) they are pipe thread. That will be different. plumbing fittings work as well as brass fittings. Hardware store items. Just take the plug and match it up. Ace the friendly Hardware Place. I always use smaller local businesses instead of big clueless box stores. Be Safe Good Luck.

 

[Zeus51]

I think (I know) they are pipe thread. That will be different. plumbing fittings work as well as brass fittings. Hardware store items. Just take the plug and match it up. Ace the friendly Hardware Place. I always use smaller local businesses instead of big clueless box stores. Be Safe Good Luck.

Thanks for the advice. With everything going on right now, I have a 8mo old at home and was trying to minimize getting out by ordering online

 

[Sharecropper]

Thank you for the clarification. I understand now. I pulled the plug by the oil filter housing. I need to get a reducer for the temperature gauge. Does 1/4" describe the square head or is it the thread also? Once I pulled it, I can't get the plug to screw into my thread identifier. I guess what I'm asking is what size threads are on the plug?

edited to add the pic

That plug above the oil filter is a 3/8" NPT. In my opinion, that is not an ideal place to install an oil temperature sensor, because there is no oil flow there. The best place to measure the temperature of the oil in in the oil pan. To install a temperature probe in the pan, you would need to remove the pan, drain the oil, and install a bung on the side of the pan for the sensor to screw into. That is exactly what I have done with my P400, the only difference being my pan is cast aluminum and your pan is steel. See photos below.

 

[Zeus51]

That plug above the oil filter is a 3/8" NPT. In my opinion, that is not an ideal place to install an oil temperature sensor, because there is no oil flow there. The best place to measure the temperature of the oil in in the oil pan. To install a temperature probe in the pan, you would need to remove the pan, drain the oil, and install a bung on the side of the pan for the sensor to screw into. That is exactly what I have done with my P400, the only difference being my pan is cast aluminum and your pan is steel. See photos below.

View attachment 794513

I agree that the oil pan is the ideal location. However, I am not a welder. What does your oil temp run in that location?

 

[Sharecropper]

I am confused. Why are you wanting to measure your oil temperature when oil pressure is more important? The very first gauges to be considered are oil pressure and water temperature. These are of paramount importance for monitoring normal engine functions. After oil pressure and water temperature, I would say that transmission temperature would be next in line of importance. THEN oil temperature, THEN maybe fuel pressure. Those are the 5 gauges, in order of importance, that should be considered to be installed. That is exactly what I am doing in my M1028 rebuild. I am fabricating a custom gauge cluster housing for mounting those 5 mechanical gauges along with a HMMWV tachometer.

 

[Sharecropper]

I agree that the oil pan is the ideal location. However, I am not a welder. What does your oil temp run in that location?

You don't need to be a welder. There are threaded bungs available which have a nut and a washer on both sides. All you have to do is drill a hole in the pan and tighten the nut on both sides. Easy peasy.

 

[Zeus51]

I am confused. Why are you wanting to measure your oil temperature when oil pressure is more important? The very first gauges to be considered are oil pressure and water temperature. These are of paramount importance for monitoring normal engine functions. After oil pressure and water temperature, I would say that transmission temperature would be next in line of importance. THEN oil temperature, THEN maybe fuel pressure. Those are the 5 gauges, in order of importance, that should be considered to be installed. That is exactly what I am doing in my M1028 rebuild. I am fabricating a custom gauge cluster housing for mounting those 5 mechanical gauges along with a HMMWV tachometer.
View attachment 794514View attachment 794515View attachment 794516

I don't have a strong argument as to why. It all started when I decided to add a coolant temp gauge. And I thought, hey, while I'm adding gauges maybe I should add an oil temp as well. It sounds like I need to switch gears to an oil pressure though, huh.......

 

[chevymike]

I don't have a strong argument as to why. It all started when I decided to add a coolant temp gauge. And I thought, hey, while I'm adding gauges maybe I should add an oil temp as well. It sounds like I need to switch gears to an oil pressure though, huh.......

Yes, coolant temp and oil pressure are the 2 most important items for monitoring an engine. If either of these go out of range (i.e. very low oil pressure or very high coolant temp), damage to your engine will occur. Thinking back, I think the only vehicles I have ever had an oil temp gauge was my VW powered vehicles. Since they are air cooled, there is no coolant so oil temp was needed along with pressure.

 

[cruzer747]

while I agree with everyone that other temps and pressures are more important, I had a thought.... if you did not want to drop the pan I believe there are oil pan drain plugs with a 1/8npt hole in them for temp sensors. You would just have to know what the thread was.

After coolant temp, oil pressure is next, it can be used to infer oil temp to some degree as well... super high, probably cold out, if not somethings wrong. super low and it may be because the engine is too hot and it is a good time to check coolant temp, slow down/stop.