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2018 Charger SXT Overheating - Thermostat or Water Pump?

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Dan C. · rep 0 · May 22, 5:49 AM · 1 replies · solved · Question

Vehicle: 2018 Dodge Charger SXT

Hey everyone,

I'm having some trouble with my 2018 Dodge Charger SXT, which has the 3.6L Pentastar engine. Lately, the temperature gauge has been creeping up, sometimes going into the red, especially when I'm stuck in traffic or driving at lower speeds. It cools down a bit on the highway, but it's still concerning.

I've checked the coolant level, and it seems okay, though it might be a little low. There are no obvious leaks that I can see on the driveway. I'm wondering if this is a common issue for these Chargers. Could it be a stuck thermostat, or am I looking at a more serious problem like a failing water pump? I haven't noticed any strange noises, but the fan seems to be running a lot.

Has anyone experienced this with their 2016-2026 Charger? Any advice on what to check first before I take it to a shop? I'm trying to figure out if this is something I can tackle myself or if it's best left to the pros. Thanks for any help!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:49 AM

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ClearTheCode admin answer:

It sounds like you're dealing with a classic overheating scenario in your 2018 Dodge Charger SXT. This is a common concern for many vehicles as they age, and the 3.6L Pentastar engine can sometimes exhibit these issues.

Here's a breakdown of potential causes and steps:

  1. Check for Diagnostic Trouble Codes (DTCs): Even if your check engine light isn't on, a pending code might exist. A common code for thermostat issues is P0128 (Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)). However, overheating can also trigger other codes related to engine temperature or misfires if it gets severe.

  2. Common Causes:

    • Stuck Thermostat: This is a very frequent culprit. If the thermostat is stuck closed, it prevents coolant from circulating properly to the radiator, leading to overheating, especially at lower speeds or idle. If stuck open, the engine might run cool, which isn't your current issue.
    • Failing Water Pump: A worn-out water pump can lead to insufficient coolant circulation. Symptoms might include a whining noise, coolant leaks from the pump itself, or visible corrosion around the pump housing. Your description of no leaks makes this less likely to be the primary cause, but it's still possible.
    • Clogged Radiator: Debris or internal corrosion can restrict coolant flow through the radiator, reducing its ability to dissipate heat. This often causes overheating at all speeds.
    • Cooling Fan Malfunction: If your cooling fan isn't engaging properly or at full speed when needed, especially in traffic, the engine will overheat. You mentioned it's running a lot, which could indicate it's working overtime to compensate for another issue, or it might not be running efficiently enough.
    • Low Coolant Level/Air in System: While you checked, a persistent low level or air pockets can severely impact cooling efficiency. Ensure the system is properly bled after any work.

  3. When to See a Shop:

    • Immediate Action: If the temperature gauge goes into the red, pull over safely and shut off the engine to prevent severe damage. Do not continue driving an overheating vehicle.
    • Professional Diagnosis: While a DIY thermostat replacement is possible for some, diagnosing the exact cause of overheating can be complex. A professional shop can perform a pressure test on the cooling system, test the thermostat, check the water pump for leaks/play, and properly diagnose cooling fan operation. They can also use specialized tools to check for exhaust gases in the coolant, which could indicate a head gasket issue (though less common for your symptoms).
    • Preventative Maintenance: Consider a cooling system flush and refill with the correct Mopar OAT (Organic Acid Technology) coolant if it hasn't been done in a while, as part of addressing the issue.
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