Kia Niro Heat Exchanger Bypass (2016-2020)

The heat exchanger on the Kia Niro is integrated with the catalytic convertor in the exhaust system. Engine coolant is routed through this extremely hot part of the exhaust to help bring the engine up to optimal operating temperature fast and to maintain that optimal operating temperature. This design is common on hybrid vehicles (e.g. the Toyota Prius) because the hybrid's combustion motor isn't always running, or does less work when it is running because it is aided by an electric motor, and subsequently may struggle to get up to optimal operating temperature.

The heat exchanger is prone to failure and may begin leaking coolant. In some cases you may notice puddles of coolant where you park. However, if the leak is internal the coolant will leak into the exhaust and be expelled from the tailpipe as white smoke or invisible vapor. If the latter, you may not be aware of the heat exchanger leak until so much coolant has leaked out that your engine overheats. In my case, I noticed because the coolant got low enough that my cabin heat stopped working.

Perform this bypass at your own risk! Bypassing the heat exchanger results in it taking longer for your engine to reach optimal operating temperature (e.g. three highway miles in my case) or may prevent it from reaching optimal operating temperature altogether (e.g. surface street driving in my case). This could result in extra wear and premature engine failure.

If you're in a pinch and can't afford a $1600 part, this is a good temporary solution. It's better than driving your car with low or no coolant while you wait for a more permanent solution.

Beware that most coolant bypass hoses are 3/4" on one end but 5/8" on the other. This project requires 3/4" ID on both ends which is a semi-rare part (see parts/tools list below). You could use one of the existing hoses and just bend it backwards, but Niro owners who have attempted that have reported the hose kinking and blocking coolant flow after a while, so I recommend finding a hose pre-molded with a 180 degree bend.

Silicone Bypass Hose - https://amzn.to/42Ej7oA
EPDM Bypass Hose - https://www.napaonline.com/en/p/NBH11600
Prediluted Coolant - https://amzn.to/42ye8FX
Automotive Picks - https://amzn.to/4im9rFj
Pliers - https://amzn.to/4iqF7JB
Zip Ties - https://amzn.to/4jIr1EA
Box Cutter - https://amzn.to/4cJhr1R
Replacement Heat Exchanger - https://www.kiapartsnow.com/genuine/k...)

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