Mack RD Truck Fuel Tanks

Frequently Asked Questions About Mack RD Truck Fuel Tanks

What size fuel tanks are available for Mack RD trucks, and how do I know which one fits my model?

Mack RD fuel tanks typically come in 50, 75, 100, and 120-gallon capacities. The correct size depends on your specific RD model year and frame configuration. Most RD600, RD688, and RD690 models from 1990-2004 can accommodate tanks ranging from 50-120 gallons. Check your door jamb sticker for your exact model designation, or measure your existing tank's mounting brackets (typically 24-26 inches apart) to ensure proper fitment. Dual tank setups are also available for extended range applications.

Are aftermarket fuel tanks as durable as OEM Mack tanks?

Quality aftermarket tanks are manufactured from 14-gauge aluminized steel or aluminum alloy that meets or exceeds OEM specifications. Look for tanks with reinforced mounting brackets, baffles to prevent fuel slosh, and proper DOT certification stamps. Aluminum tanks offer excellent corrosion resistance and weight savings (approximately 30-40% lighter than steel), while aluminized steel tanks provide good durability at a lower price point. Both materials typically last 10-15 years with proper maintenance.

What installation challenges should I expect when replacing a Mack RD fuel tank?

The most common installation challenges include aligning mounting straps with existing frame holes, rerouting fuel lines to match new tank configurations, and ensuring proper ground connections. You'll need basic hand tools plus a floor jack or transmission jack to support the tank during installation. Plan 2-4 hours for a single tank replacement. Critical steps include transferring the fuel sending unit from your old tank (if reusing), checking all fuel line connections for leaks, and properly torquing mounting straps to 35-45 ft-lbs to prevent movement.

What's the difference between round and D-shaped fuel tanks for Mack RD trucks?

Round tanks are the traditional style offering maximum capacity for their size and easier installation due to symmetrical mounting. D-shaped (or rectangular) tanks sit closer to the frame rail, providing better ground clearance and improved aerodynamics. D-tanks typically sacrifice 10-15% capacity compared to round tanks of similar dimensions but offer better protection from road debris. Most RD models can accommodate either style, though D-tanks are preferred for vocational applications where ground clearance is critical.

Do replacement fuel tanks come with all necessary hardware and fittings?

Most replacement tanks include basic mounting brackets and tank straps, but additional components are typically sold separately. You'll likely need to purchase fuel tank sending units, fuel line fittings, breather vents, and fuel caps individually. Standard NPT fittings (usually 3/8" or 1/2") are common, but verify your specific requirements. Budget an additional $75-150 for complete hardware kits including sending units, vents, and fittings. Some suppliers offer complete tank packages that include all necessary components for a plug-and-play installation.