Engine Temp Spikes Then Return Normal: What Are The Causes?

Your car’s engine is built to operate within temperatures ranging between 195 and 220 degrees Fahrenheit. Unfortunately, sometimes, the temperatures may stray outside the range for various reasons.

So, what are the reasons for engine temp spikes, then return to normal? One of the reasons is insufficient coolant in the reservoir. Other reasons include a sticking thermostat, radiator issues, and a failing water pump.

But how do you diagnose temp spikes related to the engine? This article will delve into that and the solutions to the problem.

Engine Temp Spikes, Then Returns Normal: Causes and Solutions

One of the signs of your vehicle’s cooling system malfunctioning is the engine temp spiking and then returning to normal. Below, we will address the causes of this problem.

1. Inadequate Engine Coolant:

One of the primary functions of the coolant fluid is to regulate the engine temperatures by absorbing the heat. If the levels are low, the coolant will not absorb and dissipate the heat effectively from the engine. This can cause temperature spikes in the engine for a while.

Generally, low coolant levels can be attributed to external leaks. The coolant could leak from the radiator, hose connections, or radiator hoses.

Diagnosing and Fixing the Problem:

Start by checking for green, pink, or yellow-colored coolant puddles underneath your car. In addition, wait for the engine to cool down and check the coolant levels. If the fluid is at or below the “L” marking, you must add more.

To solve this problem, you should start by fixing the cause of the leak. This includes the following.

• Tightening any loose hose connections.
• Replacing the hose clamp and cracked hoses.
• Sealing visible cracks on the radiator using an epoxy or commercial leak sealant.

Once you have fixed the leaks, the next step is to top off your coolant reservoir. Ensure the coolant level is between the full (F) and low (L) marks.

2. Sticking Thermostat:

A thermostat regulates the engine’s operating temperatures by controlling the coolant flow from the radiator.

If the thermostat sticks on the closed side for some time before opening, the engine temperature could spike and then return to normal. This is because the coolant will not flow through the radiator, preventing the engine from reaching its operating temperature.

Diagnosing and Fixing the Problem

One way to determine if the problem is with the thermostat is to turn on the heater while driving. If you lose heat while the engine temperatures are high, the thermostat is faulty.

The solution to a sticking thermostat is to replace it. Here is how to go about this:

• Step 1: Drain the coolant.
• Step 2: Unclamp the radiator hose and clamp to reach the thermostat housing bolts
• Step 3: Unscrew the bolts, securing the thermostat housing in place using a ratchet.
• Step 4: Use pliers to lift out the old thermostat. Then, remove the gasket around the hole where the thermostat was positioned.
• Step 5: Install a new gasket and thermostat in reverse order.
• Step 6: Refill the coolant.

Here’s how to replace a bad thermostat.

3. Radiator Problems

Issues with the radiator cap and fan can also cause engine temp spikes at idle or when driving at low speeds. But when you increase your driving speeds, the temperatures return to normal.

For example, if the cap is faulty and unable to maintain correct pressure, air can enter the cooling system. Consequently, the coolant will be unevenly distributed throughout the system.

Similarly, if the radiator fan is not cycling on and off correctly, it will not push enough air into the radiator. This can cause intermittent engine temperature spikes.

Diagnosing and Fixing the Problem

You can diagnose radiator issues through visual inspection. Simply check the cap and the fan for signs of damage, wear and tear. As for a clogged radiator, check for coolant flow while the engine is running.

To fix radiator problems, you must replace the cap and fan. If replacing the cap, wait for the engine to cool down. Then, unscrew the old cap by pushing it down while turning it counterclockwise and screw in the new one.

If the radiator fan is the problem, here is how to replace it:

• Step 1: Locate the radiator fan between the engine and the radiator.
• Step 2: Unplug the wire connectors running from the fan motor to the engine.
• Step 3: Remove the fan housing by unfastening the screws holding it in place.
• Step 4: Next, remove the fan from the housing and install the new one in reverse order.

Watch this short demonstration of how to replace the fan:

4. Failing Water Pump

A water pump helps circulate coolant through the engine, heater core, and radiator, preventing overheating problems. Over time, the pump’s impeller can wear out, preventing it from distributing the coolant effectively.

When this happens, you may notice temperature spikes when the engine is operating at higher RPMs. But when you slow down, the temperatures may return to normal.

Diagnosing and Fixing the Problem

A failing water pump can exhibit symptoms, such as whining, squealing, or chirping noise while the engine is running. In this case, the best solution is to replace it through the following steps:

• Step 1: Disconnect the negative battery cable and drain the coolant.
• Step 2: Unplug the fan, pulley, radiator shroud, and other accessories interfering with the pump’s removal.
• Step 3: Disconnect the hoses and pipes attached to the pump.
• Step 4: Unscrew the retaining bolts, affix the pump in place, and remove it.
• Step 5: Install the new pump in reverse sequence.

See how to replace a bad water pump.

FAQs

Below, we will respond to commonly asked questions about why the temperature gauge goes straight to high and then returns to normal.

Is it safe to continue driving when the engine temperature spikes and then returns to normal?

No, especially if the issue keeps reoccurring. Therefore, you should address the problem promptly to avoid engine overheating issues and possible engine damage.

Can you prevent engine temp spikes that return to normal after some time?

Not entirely. However, you can reduce the chances of the problem arising by regularly servicing your car. Also, inspecting the cooling system components regularly and monitoring engine temperatures while driving could help.