Frequently Asked Questions About Peterbilt 330/335/337 Transmission Coolers

Will these transmission coolers fit my specific Peterbilt 330, 335, or 337 model year?

Most aftermarket transmission coolers for Peterbilt 330/335/337 trucks are designed to fit model years 2005-2021. However, there can be variations based on your specific engine configuration (Paccar PX-6, PX-7, or Cummins ISB) and whether you have automatic or manual transmission. Always verify the cooler specifications match your truck's VIN details, particularly the transmission type and cooling system configuration. Pre-2005 models may require different mounting brackets or hose connections.

How difficult is the installation process, and what tools do I need?

Installation typically takes 2-4 hours for someone with moderate mechanical experience. You'll need basic hand tools including wrenches (typically 13mm, 15mm, and 17mm), hose clamps, and potentially a drill for mounting brackets if your truck doesn't have pre-existing holes. The most challenging part is usually routing the transmission lines and ensuring proper clearance from moving parts. Many customers report needing to drain and refill transmission fluid during installation, so have 6-8 quarts of the appropriate fluid on hand.

What's the difference between aluminum and copper/brass coolers for my application?

Aluminum coolers are lighter (typically 8-12 lbs vs 15-20 lbs for copper/brass) and offer excellent heat dissipation, making them ideal for standard duty cycles. Copper/brass units are more durable against road debris and vibration but cost 20-30% more. For heavy-duty applications like frequent towing or stop-and-go delivery routes, copper/brass coolers typically last longer. Aluminum coolers are sufficient for highway driving and lighter loads.

How do I know if I need an auxiliary transmission cooler or a complete replacement?

If your transmission temperatures regularly exceed 200?F during normal operation, an auxiliary cooler that works alongside your existing cooler is usually sufficient. Complete replacement is necessary if your current cooler is leaking, has damaged fins, or if you're experiencing transmission slippage due to overheating. Check your transmission temp gauge under load - readings consistently above 220?F indicate you need additional cooling capacity. Most 330/335/337 models benefit from auxiliary coolers when towing over 10,000 lbs regularly.

What size transmission cooler do I need for my truck?

For Peterbilt 330/335/337 trucks, cooler sizing depends on your gross vehicle weight rating (GVWR) and typical load. Standard recommendations are: 11x8 inch coolers for trucks under 26,000 lbs GVWR with light duty cycles, 11x11 inch for medium duty up to 33,000 lbs GVWR, and 13x13 inch or larger for heavy towing applications. If you operate in mountainous terrain or hot climates (regularly above 90?F), choose one size larger than recommended. The cooling capacity is measured in BTU/hr - aim for at least 20,000 BTU/hr for standard applications and 30,000+ BTU/hr for severe duty.