Frequently Asked Questions About Mack RD Truck Fan Blades & Shrouds

What years and models of Mack RD trucks are these fan blades and shrouds compatible with?

Our fan blades and shrouds are designed to fit Mack RD600, RD688, and RD690 models from 1988 through 2004. However, compatibility can vary based on your specific engine configuration (E7, E-Tech, or AI engines) and whether you have a standard or heavy-duty cooling package. We recommend checking your current fan blade part number or contacting us with your VIN to ensure proper fitment before ordering.

Are these fan blades made from plastic or metal, and which material is better for my application?

We carry both nylon composite and steel fan blades. Nylon blades are lighter weight, which reduces strain on the water pump and fan clutch while providing excellent airflow. They're ideal for most highway applications. Steel blades are more durable in extreme conditions and are recommended for severe-duty applications like heavy hauling or off-road use. The shrouds are typically made from reinforced fiberglass or heavy-duty plastic that resists cracking and warping.

How difficult is it to install a new fan blade and shroud, and what tools will I need?

Installation typically takes 2-3 hours for someone with basic mechanical experience. You'll need standard hand tools including wrenches, sockets, and potentially a fan clutch wrench (36mm or 1-7/16"). The most challenging part is usually accessing the mounting bolts in the tight engine compartment. Some installations may require removing the radiator hoses or loosening the radiator to create clearance. Always ensure the engine is cool and disconnect the battery before beginning work.

What's the difference between a 9-blade and 11-blade fan, and how do I know which one I need?

The blade count affects both cooling capacity and power consumption. 9-blade fans are standard on most RD models and provide adequate cooling for typical highway use while minimizing parasitic power loss. 11-blade fans move more air and are typically found on trucks with heavy-duty cooling packages or those operating in severe conditions. Check your current fan or look for a cooling package code on your truck's build sheet to determine OEM specifications.

How can I tell if my fan shroud is damaged and needs replacement?

Inspect your shroud for cracks, especially around the mounting points and fan blade clearance area. Missing pieces, excessive vibration, or a gap larger than 1 inch between the fan tips and shroud indicate replacement is needed. A damaged shroud reduces cooling efficiency by up to 40% and can cause overheating issues. Also check that the shroud covers at least 70% of the radiator core area and that the fan blade sits approximately halfway into the shroud depth for optimal performance.