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2017 Pathfinder Coolant Flush & Fluctuating Temp Gauge

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Mike T. · rep 0 · May 25, 1:56 AM · 1 replies · solved · Question

Vehicle: 2017 Nissan Pathfinder SL

I've got a 2017 Nissan Pathfinder SL with about 75,000 miles on it. Lately, I've noticed the temperature gauge fluctuating a bit more than usual, especially when I'm sitting in traffic or going up a long hill. It doesn't go into the red, but it definitely moves around more than it used to. The heater also seems a little less effective sometimes.

I don't think I've ever had the coolant flushed, just topped off. Is it time for a full coolant flush and fill? What kind of coolant does this model take, and are there any special considerations for bleeding the system on a Pathfinder to avoid air pockets?

Could this fluctuation also point to a failing thermostat or water pump? I want to get ahead of any major cooling system issues.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:56 AM

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ClearTheCode admin answer:

Your 2017 Nissan Pathfinder SL at 75,000 miles is definitely due for a coolant flush and fill. The fluctuating temperature gauge and reduced heater effectiveness are strong indicators that your cooling system needs attention, and a flush is an excellent starting point.

Here's a breakdown of what to consider:

  1. Coolant Flush Interval: Nissan typically recommends a coolant flush every 60,000 miles or 5 years, whichever comes first, for the initial service, and then every 30,000 miles or 2 years thereafter. Your vehicle is past due for its first major service.
  2. Causes of Fluctuating Temperature/Poor Heating:
    • Degraded Coolant: Over time, coolant loses its corrosion inhibitors and heat transfer properties. This can lead to inefficient cooling and heating.
    • Air Pockets: Air trapped in the cooling system can cause hot spots and block coolant flow to the heater core, leading to gauge fluctuations and poor heating.
    • Sticking Thermostat: A thermostat that isn't opening or closing properly can cause temperature fluctuations. This is a common failure point.
    • Clogged Radiator/Heater Core: Sediment from old coolant can accumulate, restricting flow.
    • Failing Water Pump: While less likely to cause just fluctuations initially, a failing pump can lead to poor circulation. Look for leaks around the pump.
  3. Coolant Type: Your 2017 Nissan Pathfinder requires Nissan Genuine Long Life Antifreeze/Coolant (blue in color, ethylene glycol-based). Do not mix different types of coolants. Using the wrong type can cause system damage.
  4. DIY Coolant Flush & Bleeding:
    • Drain: Drain the old coolant from the radiator drain plug and, if accessible, from the engine block drain plug (be cautious, as some are hard to reach).
    • Flush: Refill with distilled water and run the engine with the heater on high until it reaches operating temperature. Drain again. Repeat until the water runs clear. Then, fill with the correct 50/50 coolant mixture.
    • Bleeding Air: Bleeding air from the Pathfinder's cooling system is crucial. Park the vehicle on an incline with the front higher than the rear. Use a spill-free funnel on the radiator neck. Run the engine with the heater on high until operating temperature, allowing bubbles to escape. Squeeze radiator hoses to help dislodge air. This can take 20-30 minutes or more.
  5. When to See a Shop:
    • If a thorough flush and bleed doesn't resolve the temperature fluctuations or heating issues, a shop can perform a diagnostic. They can test the thermostat, check for blockages, and pressure test the system for leaks.
    • If you suspect a failing water pump or a deeper issue, professional diagnosis is recommended.
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