Frequently Asked Questions About Kenworth W990 CAC Clamps, Boots & Hoses

What size CAC boots and clamps do I need for my W990, and are they different from W900 parts?

The Kenworth W990 uses specific CAC boot sizes that differ from the W900 series. Most W990 models require 4-inch to 5-inch diameter boots for the charge air cooler connections, depending on your engine configuration. Always measure your existing connections or check your VIN-specific build sheet before ordering. The W990's updated cooling system design means many W900 CAC components are not directly interchangeable.

How often should I replace my CAC boots and hoses, and what are the warning signs of failure?

Under normal operating conditions, silicone CAC boots typically last 3-5 years or 300,000-500,000 miles. Look for these failure indicators: oil residue around clamp areas, soft or spongy spots on boots, visible cracks or splits, loss of turbo boost pressure, or increased fuel consumption. Inspect your CAC system every oil change and replace components at the first sign of deterioration to prevent roadside failures.

Do I need special tools to install CAC clamps and boots, and how tight should the clamps be?

Installation requires basic hand tools, though a torque wrench is recommended for consistent results. T-bolt clamps should be torqued to 60-90 inch-pounds, while constant torque clamps typically require 50-70 inch-pounds. Over-tightening can damage boots and cause premature failure. Apply a thin layer of silicone lubricant to boot surfaces for easier installation and better sealing. Allow 30 minutes for components to settle before final torque check.

What's the difference between silicone and rubber CAC boots, and which is better for my W990?

Silicone boots withstand temperatures up to 500?F and last significantly longer than standard rubber, making them ideal for the W990's high-performance applications. While silicone costs 2-3 times more initially, they resist oil degradation, maintain flexibility in extreme cold, and typically outlast rubber boots by 2-3 years. For trucks running heavy loads or in extreme climates, silicone is the recommended choice.

Are aftermarket CAC components reliable, or should I stick with OEM Kenworth parts?

Quality aftermarket CAC components from reputable manufacturers often match or exceed OEM specifications at 30-50% less cost. Look for boots made from 4-ply or 5-ply reinforced silicone with aramid fiber reinforcement. Ensure any aftermarket parts meet SAE J20 specifications and are rated for your operating temperatures and pressures. Many professional drivers successfully use aftermarket components, but avoid unusually cheap options that may use inferior materials.