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2018 XT5 Low Coolant & Sweet Smell - Leak Detection Help!

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Chris P. · rep 0 · May 22, 4:02 AM · 1 replies · solved · Question

Vehicle: 2018 Cadillac XT5 Premium Luxury

Hi everyone,

I've got a 2018 Cadillac XT5 Premium Luxury with the 3.6L V6 engine. For the past few weeks, I've noticed a faint sweet smell, especially after driving, and I've had to top off the coolant reservoir a couple of times. It's not a huge amount, but it's definitely going down.

I've looked around the engine bay, but I can't see any obvious puddles or drips on the ground. I'm worried about an internal leak or something more serious. Has anyone experienced this with their XT5? What are the common leak points I should check?

Any tips on how to find this elusive leak would be great!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:02 AM

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Hello Sarah,

A sweet smell and consistently low coolant levels on your 2018 Cadillac XT5 are classic signs of a coolant leak. Even if you don't see puddles, the coolant can evaporate quickly on hot engine components, leaving little to no trace on the ground.

Common Coolant Leak Points on XT5 (3.6L V6):

  1. Water Pump: A common failure point. Look for residue or drips around the front of the engine, near the accessory belt.
  2. Radiator Hoses & Clamps: Check the upper and lower radiator hoses, as well as the smaller heater hoses, for cracks, swelling, or leaks at the connection points.
  3. Radiator: Inspect the radiator fins for any discoloration or wet spots, especially along the seams.
  4. Coolant Reservoir & Cap: The reservoir itself can crack, or the cap might not be sealing properly, allowing pressure loss and evaporation.
  5. Thermostat Housing: Leaks can occur around the thermostat housing gasket.
  6. Heater Core: If you notice a strong sweet smell inside the cabin, especially when the heater is on, it could indicate a leaking heater core.

Diagnostic Steps You Can Take:

  • Visual Inspection (Cold Engine): With the engine cold, carefully inspect all hoses, the radiator, and around the water pump for any pinkish/orange (Dex-Cool) residue. Use a flashlight to get into tight spots.
  • Pressure Test: The most effective way to find a slow leak is with a cooling system pressure tester. This tool pressurizes the system while the engine is cold, making leaks more apparent. You can rent these from auto parts stores.
  • UV Dye: Add a UV dye specifically designed for cooling systems to your coolant. Drive for a day or two, then use a UV light (black light) to easily spot the leak, as the dye will glow brightly.

When to See a Shop:

  • If you're unable to locate the leak yourself, or if the leak appears to be from a difficult-to-access area (like the heater core or behind the engine).
  • If you notice white smoke from the exhaust or oil/coolant mixing, which could indicate a head gasket issue (though less likely with just a sweet smell).

Addressing a coolant leak promptly is crucial to prevent engine overheating and potential severe damage.

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