Symptoms of a Bad or Failing Heater Bypass Tube

Schedule Vehicle Engine Cooling Inspection
Service Area

$0.00

Upfront, Transparent Price
Average rating from 129,829 customers who received a Vehicle Engine Cooling Inspection.

The heater bypass tube is a cooling system component found on many road going cars and trucks. It’s purpose is to serve as a cooling system passage that bypasses the thermostat, so that there is coolant flow even when the engine thermostat is closed. The coolant bypass tube provides a passage for minimum coolant flow, so that the engine does not overheat from insufficient cooling when the thermostat is closed and restricting coolant flow.

While servicing the bypass tube is not generally considered routine maintenance, it is still prone to the same issues that all cooling system components are susceptible to, and can sometimes require attention. Usually a faulty heater bypass tube will produce a few symptoms that can alert the driver of an issue.

Coolant smell

One symptom of an issue with heater bypass tube is a coolant smell from the engine bay. Most heater bypass tubes use an o-ring or gasket to seal the bypass tube to the engine. If the o-ring or gasket wear out or tear, coolant will begin to leak from the bypass tube. This may produce a coolant smell from the vehicle’s engine bay. Some coolant bypass tubes are located near the top of the engine, and as a result may produce a coolant smell far before any coolant can be visibly detected without opening the hood.

Coolant leak

The most common symptom of an issue with the heater bypass tube is a coolant leak. If the bypass tube gasket or o-ring become damaged, or the bypass tube leaks due to excessive corrosion it may cause a coolant leak. Depending on the severity of the leak, coolant may or not leak onto the floor or underneath the vehicle. A faulty gasket or o-ring may require a simple replacement of the seal, while a corroded tube will usually require replacement.

As the coolant bypass tube is a component of the engine’s cooling system, it’s failure can lead to engine overheating and potential serious engine damage. If your vehicle’s bypass tube is leaking, or has another issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the bypass tube requires replacement.


Next Step

Schedule Vehicle Engine Cooling Inspection

The most popular service booked by readers of this article is Vehicle Engine Cooling Inspection. Yourmechanic’s technicians bring the dealership to you by performing this job at your home or office 7 days a week between 7AM-9PM. We currently cover over 10k cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Vehicle Engine Cooling Inspection reviews

Excellent Rating


YourMechanic Vehicle Engine Cooling Inspection Service

Average Rating

4.9/5

Number of Reviews

129,829

Rating Summary
121,202
4,801
964
664
2,198
121,202
4,801
964
664
2,198

Jeffrey

26 years of experience
859 reviews
Jeffrey
26 years of experience
Kia Sorento - Tune-up - Lancaster, South Carolina
Jeff arrived at 10:15 AM as promised. He did a great job. He is a consummate mechanic. Also, he listened to other problems that I am having and helped me understand the possible reasons. He was very friendly and respectful.
Dodge Ram 1500 - Control Arm Assembly Replacement (Front Lower Left) - Charlotte, North Carolina
Excellent job! Very friendly and courteous. He did a great job, and even took the time to show me what was wrong, and how he fixed it. Thanks.

David

15 years of experience
599 reviews
David
15 years of experience
Audi A4 - Oil Change - Pleasant Hill, California
Great skils !!! Super professional attention on details . Strongly recommend!!!
Kia Spectra - Car is making a noise - Emeryville, California
On time, efficient, knowledgeable, and gave me all info i needed to get it fixed. Will be calling for follow-up.

Steven

25 years of experience
72 reviews
Steven
25 years of experience
BMW 325e - Car is not starting - Murrieta, California

Peter

42 years of experience
1285 reviews
Peter
42 years of experience
Honda Accord - Brake Pads Replacement (Rear) - Phoenix, Arizona
Excellent job, highly professional. I would highly recommend.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE