Frequently Asked Questions About Mack RD Truck Radiators

Will these radiators fit my specific Mack RD model year, and what are the differences between RD688, RD690, and RD800 radiators?

Mack RD radiators are designed for specific model years and configurations. RD688 models (1990-2004) typically use a 4-row copper/brass or aluminum radiator with specific mounting brackets. RD690 and RD800 models (2000-2007) often require wider core radiators due to higher horsepower engines. Always verify your truck's VIN and engine model (E7, MP7, or MP8) before ordering, as coolant capacity and mounting points can vary. Most radiators fit multiple years within a model range, but pre-2000 models may have different inlet/outlet configurations than later versions.

Should I choose aluminum or copper/brass construction, and how long can I expect each type to last?

Aluminum radiators typically weigh 40-50% less than copper/brass units and offer better cooling efficiency with modern multi-row designs. They generally last 8-12 years with proper maintenance. Copper/brass radiators are more resistant to road debris damage and easier to repair locally, lasting 10-15 years on average. For heavy-duty applications or areas with extreme temperature swings, copper/brass provides more durability. Aluminum is preferred for fuel efficiency and overall cooling performance in most highway applications.

What are the most common installation challenges, and can I install this myself?

Installation typically takes 3-4 hours for experienced mechanics. Common challenges include: removing the old radiator without damaging the AC condenser, properly aligning upper and lower mounting brackets, and ensuring all hose connections seal correctly. You'll need basic hand tools plus a coolant recovery system. Critical steps include checking fan shroud clearance (minimum 1 inch), verifying transmission cooler line routing on automatic models, and properly bleeding air from the cooling system. Many customers successfully DIY install, but professional installation is recommended if you're unfamiliar with heavy truck cooling systems.

What's included with the radiator, and what additional parts might I need?

Most Mack RD radiators come with mounting brackets and rubber isolation mounts pre-installed. However, you'll typically need to purchase separately: upper and lower radiator hoses (specific to your engine model), hose clamps, coolant (approximately 12-15 gallons), and potentially a new radiator cap if yours is over 5 years old. Thermostats, fan clutches, and overflow bottles are not included but should be inspected during installation. Budget an additional $150-300 for these supplementary parts and fluids.

How do I identify the correct radiator by core size and inlet/outlet positions?

Mack RD radiators are identified by core dimensions (height x width), typically ranging from 36"x34" to 42"x34". Measure your existing radiator from tank seam to tank seam. Inlet positions are designated as driver or passenger side, with outlets usually opposite. Most RD models use 2.5" upper and 3" lower connections. Cross-reference your radiator part number (located on the top tank) with OEM specifications. Common OEM numbers include 21318455, 21318456, and 4410002103. If your original tag is missing, count the rows (4-row or 6-row) and note whether tanks are vertical or horizontal.