Believe it or not, but one of the biggest returns here at Steiner Tractor Parts is radiator caps. There are a few different styles of radiator caps, and radiators get replaced so frequently that it can be difficult to know exactly what you should be asking for.

When you are ordering a new radiator cap, here’s what you need to know.

1. Does your tractor have the original radiator? Radiators can be interchangeable. Just because you have a Ford 9N doesn’t mean it has the original or correct radiator on it. In fact, chances are good it’s been swapped over the years for a radiator from a Ford 8N – which uses a different radiator cap. This applies to all models of tractors, but we see swaps from the original most often on Ford and Farmall tractors.

2. Is your radiator pressurized? A non-pressurized cap is flat on the underside, and a pressurized one will have a flap to create a seal. Because pressurized systems tend to circulate the water better, it’s not uncommon for a tractor that would originally have a non-pressurized system to get an “upgrade” to a pressurized system over the years. The underside of the cap can be a good initial clue into what you’re working with.

3. How does the cap connect to the neck of your radiator? Some radiator necks have a jaw that the cap grabs onto and seals tight (common in pressurized systems). Other types are held on but not locked on, with an ear that can let the pressure release.

4. If the cap is pressurized, how much pressure? There’s a difference between a cap that will hold 4 pounds of pressure and a cap designed for 6 pounds.

A simple awareness of these things can often go a long way in helping you order the right replacement for your radiator cap. If you’re still unsure, though, let the folks at Steiner know when you place your order. They’ll help you double-check to be sure you’re getting the right part.