Temperature Sender: What Is It and Why Should Your Boat Have One?

If you have a boat, then you know how important it is to keep an eye on the temperature. After all, you don't want your engine to overheat, do you? But what do you need to keep track of that? Well, one of the devices you need is a temperature sender.

In this blog post, we'll tell you everything you need to know about temperature senders and why your boat should have one installed in your boat.

What Is the Temperature Sending Unit On a Boat?

The boat temperature sending unit or water temperature sender unit is a small device that is placed in the boat's engine compartment. It is used to measure the temperature of the engine coolant (Ethylene Glycol mixed in the same ratio with Water) and send a signal to the boat's electronic control unit.

The sending unit is usually located near the thermostat housing and/or on the intake manifold itself.

Most boats have an engine temperature gauge, which is great for monitoring your engine's health. But what if your engine coolant is overheating and you don't realize it? That's where a temperature sender comes in. It helps counter the damage that can occur when your boat’s engine coolant is running hot.

How Does a Coolant Temp Sender Work?

The temperature sender is usually made of brass or copper and consists of a sensor that is mounted in the cooling system and a transmitter that sends a signal to the boat computer controller panel. The sensor is usually a thermistor that changes resistance with temperature.

The transmitter converts the resistance of the sensor into a signal that the boat computer panel can interpret.

When the engine's coolant temperature rises above an undesirable point, the temperature sender sends a signal to the boat's computer controller unit, which then activates the boat's cooling system.

Tips to Maintain a Temperature Sender on your Boat

  1. Check the temperature sender’s probes regularly for corrosion or debris and clean them with a dry cloth.
  1. Inspect the wiring and connections to the temperature sender regularly.
  1. Inspect the temperature sender for cracks or damage.
  1. Replace the temperature sender if it is damaged or shows signs of wear.
  1. Use only high-quality temperature senders designed for marine use. 
  1. Check the manufacturer’s instructions for specific maintenance tips for your model of temperature sender.

How Do you Check Temperature Sender Unit?

To check the temperature sender unit, you will need to remove it from the engine and check it with a multimeter. Set the multimeter to the ohms setting and attach the probes to the sender unit.

The multimeter should read a low resistance when the engine is cold and a higher resistance when the engine is hot. If the multimeter does not read a resistance, then the water temperature sender is faulty and needs to be replaced.

How to Replace a Water Temperature Sender

Here are the steps to follow to replace a water temperature sender unit:

  1. Start by disconnecting the negative battery cable to prevent any electrical shorts. 
  1. Next, remove the old water temperature sender from the engine. This will require removing any bolts or screws that are holding it in place.
  1. Once the old sender has been removed, clean the area where the new sender will be installed. This will help ensure a good seal.
  1. Install the new water temperature sender in the engine, and secure it in place with the bolts or screws.
  1. Reconnect the negative boat battery cable. 
  1. Start the boat’s engine and check the new water temperature sender to make sure it is working properly.

FAQs

What is the difference between temperature sensor and temperature sender?

The difference between a boat temperature sensor and a boat temperature sender is that the boat water temperature sensor is the device that actually measures the temperature of the engine’s coolant, while the boat temperature sender is the device that sends the temperature information to the boat's controller panel.

Are all temp sending units the same?

There are many different types and styles of temperature sending units, but they all perform the same basic function, which is to measure the temperature of a boat’s engine coolant and send a signal to a boat’s computer controller unit.

Can you match boat water temperature gauge and sender between brands?

It is not recommended to match boat water temperature gauges and senders between brands because doing so can cause compatibility issues. For example, a boat water temperature gauge from one VDO might not work properly when paired with a sender from Faria.

Additionally, mismatched gauges and senders can also lead to inaccurate readings. Therefore, it is best to use gauges and senders from the same brand in order to avoid any potential problems.

Wrapping up

If your boat doesn't have a temperature sender, it's time to get one! A temperature sender is a small device that measures the temperature of the engine coolant used in your boat and sends that information to a controller inside the boat. This is a crucial piece of equipment for any boat because it helps keep your boat engine running at the optimal temperature and prevents any potential damage to the boat engine.

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