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Coolant Leak on 2018 Tiguan - Smells Sweet, Level Dropping

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David L. · rep 0 · May 22, 4:37 AM · 1 replies · solved · Question

Vehicle: 2018 Volkswagen Tiguan S

Hi everyone,

I've got a 2018 Volkswagen Tiguan S with about 50,000 miles, and I've been noticing a sweet smell, especially after driving, and my coolant level seems to be dropping pretty consistently. I have to top it off every couple of weeks. I haven't seen any obvious puddles under the car, but I'm worried about where it's going.

Could this be a common issue with the water pump or thermostat housing on these Tiguans? I've heard some VW models have problems with plastic components failing. What should I be checking for, or is this something I need to get into the dealer for right away?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:37 AM

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ClearTheCode admin answer:

Experiencing a sweet smell and a dropping coolant level without visible puddles is a classic sign of a slow coolant leak, and you're right to be concerned about the water pump or thermostat housing on your 2018 Volkswagen Tiguan S.

  1. Common Causes:

    • Water Pump Failure: The water pump on many modern VW engines, including the 2.0T in your Tiguan, often has plastic components that can become brittle and crack over time, leading to leaks. The leak might be slow and evaporate before hitting the ground.
    • Thermostat Housing Leak: Similar to the water pump, the thermostat housing is another common point of failure due to plastic components or seals degrading.
    • Hose Leaks: Less common but still possible are leaks from coolant hoses or their connections.
    • Head Gasket (Less Likely but Possible): If the leak is internal, it could be a head gasket issue, but this usually comes with other symptoms like white smoke from the exhaust or oil contamination.

  2. When to See a Shop:

    • Immediately: A persistent coolant leak can lead to engine overheating, which can cause severe and expensive damage. Do not delay addressing this.
    • Before Driving Long Distances: Avoid long trips until the issue is resolved.

  3. What to Expect at the Shop:

    • A technician will perform a pressure test on the cooling system. This involves pressurizing the system and then inspecting for leaks, which often become more apparent under pressure.
    • They will closely inspect the water pump, thermostat housing, and all coolant hoses for signs of seepage or dried coolant residue.
    • If a leak is found at the water pump or thermostat housing, replacement of the entire assembly is usually the recommended fix. This can be a moderately expensive repair due to parts cost and labor involved in accessing these components.
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