My car does not have a temperature gauge and I need one! It seems like it would be important to monitor the temperature of your car since overheating could be the demise of the engine leading to a car that gives up the ghost. To avoid that, I pursued what type of temperature gauge I should install and how to install them! I answer your questions on whether you want a mechanical or electrical gauge and how to install them.
There are plenty of aftermarket gauges and there seems to be two main types. So which do I want, and why is an electric or mechanical temperature gauge better than the other?
An electric temperature gauge is preferred over a mechanical gauge for the ease of installation, the routing lines are not fragile like with a mechanical gauge, and it avoids routing fluids into the passenger compartment. Mechanical gauges are beneficial for a full dial sweep (temp range) and to see the temp when the car is off.
There are several aspects to consider between using a mechanical or electrical gauge. Both are simple enough to install but have some important factors to consider including cost, ease of install, accuracy, and application.
Key Takeaway
Electrical temperature gauges are recommended over mechanical. These are simpler to install. All you need to do is sort out is the proper sending unit, and find a power source wire. Then run 1 wire from the sender to the gauge and you are done. If you are unsure of your ability to do the install, or are looking for the quick, easy way, the electrical gauge is for you.
Electric Temperature Gauges
Electric temperature gauges operate from a voltage coming from the sending unit, generally installed on the intake manifold, water neck, or water pump and alters the voltage with a fluctuating resistance change as the temperature goes up and down.
Many engines already have a sender unit installed which mechanically moves a resistor to cause a fluctuation in the voltage which is sent to the gauge.
Preferred Features of an Electric Temperature Gauge
Electric temperature Gauges are very easy to install and maintain a high level of accuracy and the routing lines are much less fragile.
Electrical gauges to not have the fragile lines to run into the passenger compartment that are difficult to route and can get plugged or being that make the installation much easier
Electrical gauges only require 3 wires. One power source, one ground, and one sender.
Electrical gauges are much easier to set up than mechanical gauges because there is no plumbing to route fluid to the gauge.
Electrical temperature gauges are considered to be just as reliable because they do not have the possibility of getting plugged or bent feed lines like mechanical gauges do.
The Downsides to an Electric Temperature Gauge
Fluid lines are routed from the sender on the manifold, head, or water pump to inside the passenger compartment. They are fragile and when they fail, they leak fluid.
Electric Temperature Gauges are generally slightly more expensive than mechanical gauges.
Mechanical gauges will work even when the power is turned off to the car.
Race cars use mechanical for this reason – to still be able to see the temperature when the car is shut off since it is not connected to the electrical system.
Electric temperature gauges can only operate efficiently in a narrower temperature range than that of mechanical gauges. The increased sweep of mechanical gauges helps read the gauge more accurately.
Installation of an Electrical Temperature Gauge
When installing an electrical temperature gauge, getting the proper sender (if your car is not already equipped with one) is critical.
Match up the proper sender with the gauge by looking on the resistance to the gauge. Typically they will say something on the back like (0 to 30 ohms) or (0 to 90 ohms) etc.
Of course you will need to match the thread size of the sender with the block
The actual installation is simple.
Installation Steps for an Electrical Temperature Gauge
- Pick a location to install the sender unit. Generally there is a place for this on the intake manifold, the head, or the water neck, or water pump.
- Install a sender unit with the proper threads to match what is on the engine.
- Match the sender unit to the gauge. (gauges indicate the resistance ranges that they operate between and these should be used to find the proper sending unit.
- Mount the gauge.
This video is a helpful visual of the steps.
Mechanical Temperature Gauges
A mechanical temperature gauge operates with a bourden tube in the engine which causes the fluid to rise as the temperature increases. From the bourdon tube sender, oil is pumped to the gauge.
In the gauge there is a long, sealed capillary tube that contains an ether gas that expands when the probe tip is heated. The expansion of the gas is what pushes the needle forward on the gauge.
Preferred Features of a Mechanical Temperature Gauge
Mechanical temperature gauges work over a wider temperature range with a wide sweep on the gauge.
The wider sweep on the gauge makes the temperature easier to read accurately.
Mechanical Temperature gauges are generally slightly cheaper than electrical temperature gauges.
They also continue to operate when the car is turned off since they are not connected to the electrical system. Race cars tend to use mechanical temperature gauges so that they can continue to monitor the temperatures even when the car is off.
The Downsides to a Mechanical Temperature Gauge
Mechanical lines can be kinked so more time planning the route through the firewall is needed than simply running one wire with electrical gauges.
Mechanical gauges route fluid to the gauge which is fragile and care has to be taken to not break the line. It eventually wears out and can leak into the passenger compartment.
Installing a Mechanical Temperature Gauge
- Pick a location to install the sender unit. Generally there is a place for this on the intake manifold, the head, or the water neck, or water pump.
- Install a sender unit with the proper threads to match what is on the engine.
- Route the line from the sender to the gauge. Ensure that it is in a protected area and out of the way.
- Mount the gauge.
The probe should be installed into the top of the intake manifold. There are generally ports pre-threaded for this type of application in the manifold, and you will need little more than a mounting nut to adapt the sending unit to the manifold.
Alternative Temperature Gauge Options
Digital Stepper Motor Gauge
One more common gauge is the digital stepper motor. I will not cover this gauge in as much detail, but it should be mentioned here.
The digital stepper motor gauges are the most accurate, and most expensive gauges that you can install. These are not needed unless on a high performance application.
Temperature Sensor Light
The second alternative to all of this is to not add a temperature gauge at all. You can add a temperature light if there is not one already. The light adds more of a fool-proof style temperature gauge and is suitable for most people anyways. With a temperature light, Light Off = Keep Driving
Light On = Stop and cool down the engine
This simplicity is easy to handle for everyone and a temperature sensor light is adequate in most cases.
Not adding one will be just fine. And simply keep an eye on the temperature light, fluid levels, and checking the light periodically to ensure it works.
Key Takeaway
Electrical temperature gauges are recommended over mechanical. These are simpler to install. All you need to do is sort out is the proper sending unit, and find a power source wire. Then run 1 wire from the sender to the gauge and you are done. If you are unsure of your ability to do the install, or are looking for the quick, easy way, the electrical gauge is for you.
