Diesel Exhaust Brake Fundamentals

Safer Towing, Speed Control by Installing an exhaust Brake

An exhaust brake is the must have upgrade for any diesel owners whom regularly tow with their pickups. Whether you tow a small camp trailer through the mountains or heavy equipment from job site to job site, an exhaust brake is an economical add-on that significantly increases safety and prolongs the life of your braking system. An exhaust brake is a simple device installed at the outlet of the turbocharger and increases exhaust backpressure on demand to effectively provide engine braking. An exhaust brake is a great addition to the factory Tow/Haul setting so many trucks come factory equipped with. Many modern diesels come with factory equipped exhaust brakes, although this systems rely on VGT activity and effectively controls backpressure by closing vanes in the turbine housing as opposed to utilizing a standalone valve.

How Exhaust Brakes Work

Exhaust brakes help a truck slow down by restricting exhaust flow. Exhaust brakes are generally installed directly behind the turbocharger turbine outlet, but can be installed virtually anywhere in the exhaust system. A simple exhaust brake consists of a butterfly valve inside of a tubular housing. A solenoid or mechanical attachment opens/closes the exhaust brake as necessary. In the open position, exhaust flows normally. In the closed or partially closed position, exhaust backpressure is greatly increased. The backpressure works against the engine as it pumps air out of the cylinders, helping to slow down the engine and therefore the vehicle. Some exhaust brakes are completely mechanical, while others communicate directly with the engine's PCM (computer) to provide precision on-demand braking. Exhaust brakes are great for controlling speeds when towing downhill or bringing heavy loads to a halt while saving the truck and trailer brakes by reducing use.

Exhaust brake operation diagram

Exhaust Brake Pros

Exhaust Brake Cons

Provides better control of vehicle speed when hauling and towing, especially on downhill grades

Presents a small restriction in the exhaust system - negligible for most trucks when the exhaust brake valve is in the open position

Reduces truck and trailer brake wear

Helps prevent truck and trailer brakes from overheating

Decreases distance in which a truck and trailer can be stopped, particularly beneficial in an emergency situation

Exhaust leaks before the location of the exhaust brake should be repaired to ensure maximum efficiency. A marginal sacrifice in performance may accompany the install, but it's negligible unless you're looking for total performance. The trade-off is well worth it if you use your truck for its intended purpose. Exhaust brakes are available for a variety of applications, although some naturally aspirated engines may not be compatible.