Frequently Asked Questions About Peterbilt 357/378 Radiators

Will these radiators fit my specific Peterbilt 357 or 378 model year?

Our Peterbilt 357/378 radiators are designed to fit models from 1987 through 2007. However, compatibility can vary based on your engine type (CAT, Cummins, or Detroit) and whether you have a standard or extended hood. Before ordering, check your current radiator's core dimensions and inlet/outlet positions. Most radiators will have a part number stamped on the top tank that you can cross-reference. If you're unsure, contact us with your VIN and we'll help verify the correct fit.

What's the difference between aluminum and copper/brass radiators for my truck?

Aluminum radiators are lighter (typically 40-50% less weight) and offer better cooling efficiency with modern multi-row designs. They're also more resistant to corrosion from coolant. Copper/brass radiators are heavier but can be repaired more easily by local shops if damaged. For most 357/378 applications, we recommend aluminum unless you specifically need the repairability of copper/brass. Both types will last 8-12 years with proper maintenance, though aluminum tends to handle the vibration of long-haul trucking better.

Can I install a new radiator myself, or do I need special tools?

Installation typically takes 3-4 hours for someone with basic mechanical skills. You'll need standard hand tools, a coolant drain pan, and ideally a helper for lifting. The main challenges are disconnecting the transmission cooler lines (if equipped) without damaging them and properly burping the cooling system afterward. Make sure to transfer your overflow tank fitting and temperature sender from the old radiator. New radiator mounts and hoses are recommended during installation. Many drivers successfully DIY this job, but if you're not comfortable working with cooling systems, professional installation runs $200-400.

How do I know if I need a radiator with or without an oil cooler?

Check your current radiator for oil lines running to it - these are separate from the transmission cooler lines and typically connect on the driver's side. Trucks with CAT engines often have engine oil coolers built into the radiator, while some Cummins ISX engines use separate coolers. If you see four lines going to your radiator (two coolant, two oil), you need one with an oil cooler. Running without an oil cooler when your engine requires one can cause severe engine damage. When in doubt, match your existing setup exactly.

What causes premature radiator failure in 357/378 trucks, and how can I prevent it?

The most common causes are coolant contamination (mixing different coolant types or not changing it every 2-3 years), excessive vibration from worn motor mounts, and pressure issues from faulty radiator caps. Scale buildup from hard water is another major killer. To maximize radiator life, use only distilled water with your coolant, maintain the correct 50/50 mix, replace your radiator cap every time you change the radiator, and ensure your fan clutch is working properly to prevent overheating. Regular pressure testing can catch problems before they leave you stranded.