I only see two ports on the cylinder head, one for the Coolant Temperature Sensor used by the Computer and one for the Temperature Idiot Light. Unfortunately, the hole for the Idiot Light gage is way too small to accept the bulb sensor on the typical after market mechanical temp gage. How are people adding aftermarket gages?

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'81 D150 with "Lean Burn"

One technique is to drill and tap the thermostat housing and install the sender there. That way you can "see" the thermostat open as the engine warms up.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I put my aftermarket temp sender in the thermostat cover.
You need to off-set it to the side so it does not hit the top of the thermostat.
DD

I thought about putting one in the thermostat cover, but in that position, isn't it correct that you wouldn't get a reading until after the thermostat opened?

Wouldn't that run the risk of the gage not registering the problem of an engine over heating on one side of a stuck closed thermostat since the sensor is on the other side?

i guess the idiot light would be a backup in that case, but the whole point of a gage is that by the time most Idiot lights come on, it's too late!

Which leads me to the next question, what is the normal temperature operation range (green), caution range (yellow) and the Max red line?

I thought about using a "Tee" in the heater hose, since there does not seem to be a shut off valve in the my heater line. (Is there supposed to be one?)

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'81 D150 with "Lean Burn"

I have drilled and retapped the head's mounting area larger.
I have also put a sender in the water pump's inlet, so I can see how well the radiator is working. That is a bit of a pain, if you have to replace the water pump.
DD

There's also this option:

http://www.steigerperformance.com/PRODUCTS/sp40001.html

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vm

I don't know what degree of precision you are going for, and I further don't know what works with what year-wise, but have you considered getting a junkyard instrument cluster from a later (or better optioned, or whatever) truck?

The sending unit would fit in the same hole. (It may even be the same unit for I-lights and gauges. I have no idea, but I'm sure several people here do.)

Drilling and tapping the hole in the head makes the most sense otherwise, but that's a lot of work and diminished returns if all you are looking for is an improvement upon an I-light.

Wait a sec, here.

What year and model truck are you working on that has a temperature idiot light rather than a gauge? That is very unusual in Mopars, even bottom-of-the-line Mopars.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I put mine in the top left corner of my radiator, it doesn't register untill the stat opens, but it does show the temp. If you are worried about the stat not opening, replace it.

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

I don't suppose you have a clever way to drill and tap the head with it on the engine? I could open up the small temp gage sender hole further back by the side of the valve cover.

My aftermarket temp gauge is currently installed in front of the head as in Doc's picture. The PO cut the wire to the Coolant Temperature Sensor for the computer and put a sensor for an aftermarket gage in it's place. Gee, I wonder why the Lean Burn isn't working quite right !!??

I'm truly surprised it runs as well as it does, but I'm looking for some place to move the gage sensor to, so that I can reinstall the temp sensor for the computer.

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'81 D150 with "Lean Burn"

I've seen these, good idea, but they even caution about the fact that the gage won't register until the thermostat opens. I'm looking to make a tee similar to this for the heater hose. Anybody know why it wouldn't work in the heater hose?

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'81 D150 with "Lean Burn"

I do need another cluster, part of the needle on the speed fell off ! What do they get for used clusters and how do I figure out what years and models will fit?

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'81 D150 with "Lean Burn"

What can I day, it's an '81 Dodge D150 1/2 ton Pickup. It has power steering but no power brakes, i think it had A/C, but it's been ripped out.

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'81 D150 with "Lean Burn"

I have been considering the same problem for an upcoming megasquirt conversion, and I am leaning towards a modified freeze plug in the middle position. I am thinking that this should give a good indication of the coolant temp.

That will work fine, as long as there is not a hot water shut off valve in the system. Just make sure it is in the heater hose that comes from the head.

Some late computer Fords have the temp sensor in the heater line.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225