What is the Pre-Heater Hose all about?

Most engines today are fuel injected, but there are still a few vehicles around that use carburetors instead. Whether you own a classic car, or are driving a hand-me-down vehicle without fuel injection, you’ll have a number of different parts that need regular service.

The pre-heater hose extends from the exhaust manifold to the air filter assembly. Its only job is to send pre-heated air from the engine into the air filter and then the carburetor during cold weather. It’s a pretty straightforward setup. Warm air is sent from the exhaust manifold into the air filter assembly. There, a flapper is designed to activate depending on temperature. If the exterior temperature is relatively warm, then fresh air is directed into the carburetor.

If the temperature is low, warmed air is sent to the carburetor. It helps ensure proper fuel delivery during cold weather, as well as to prevent the carburetor from icing up during winter. It is also important for passing your emissions test.

Keep in mind:

• Pre-heater hoses will crack and wear over time through normal wear and tear.
• The pre-heater hose should be inspected visually during normal maintenance (oil changes).
• If the pre-heater hose fails during warm weather, you may not even notice any change in engine operation.

How it's done:

• The hood is opened and the engine is allowed to cool completely
• The cooling system is drained and the defective pre-heater hose is removed
• The new pre-heater hose is connected and the cooling system is refilled
• The cooling system is checked for any coolant leaks
• The engine is run and cleared of codes and road tested for proper cooling system operation

Our recommendation:

While the pre-heater hose is not necessary for vehicle operation in most instances, it is an important component, particularly if you have to pass an emissions test. If you’ve noticed that your car doesn’t crank well during cold weather, or have seen cracks or other damage to the pre-heater hose, have it replaced by one of our expert mechanics.

What common symptoms indicate you may need to replace the Pre-Heater Hose?

• Cracks in the hose
• Bulges in the hose
• Hard starts during cold weather
• Carburetor icing during winter

How important is this service?

The pre-heater hose isn’t absolutely crucial to vehicle operation, but one in working order will go a long way. You’ll need it to pass emissions and safeguard the carburetor from freezing during winter. We recommend having the hose replaced as soon as possible if it's deemed faulty.