Parts for your 2006 Ford Transit-Radiator cap

Does a 2006 Ford Transit have a radiator cap?

For the 2006 Ford Transit, a traditional radiator cap on the radiator itself isn’t used. Instead, the cooling system is a sealed, pressurised setup that uses a cap on the coolant expansion (header/degas) tank. This design choice is confirmed across technical sources: Ford’s workshop manual (Engine Cooling, Section 303-03) describes a pressurised expansion tank system, the 2006 Transit owner’s manual refers owners to the “coolant expansion tank cap” for checks and warnings, and Ford’s OE parts catalogues list a “reservoir/expansion tank cap” rather than a “radiator cap,” with the radiator shown without a filler neck.

Why no radiator cap? Ford engineered these Transits with a remote, pressurised expansion tank to improve reliability, safety and packaging. Moving the pressure cap off the radiator helps with consistent system pressure, cleaner deaeration of coolant, and easier bleeding after a coolant change. It also allows the radiator to sit lower for better under‑bonnet packaging and crash performance, and reduces the scald risk that came with old-style caps sitting up front. In practice, the expansion tank cap is the pressure control point for the system, performing the same job an old radiator cap once did—holding pressure to raise boiling point, and venting to the overflow path if pressure gets too high.

Owners looking for a “radiator cap” for a 2006 Transit should instead be searching for the coolant expansion tank cap. It’s the plastic, threaded cap on the translucent reservoir bottle. Typical caps for these models are rated around 140 kPa (20 psi), though the correct rating should always match what’s specified for the exact engine and VIN. If the cooling system is losing coolant with no obvious leaks, hoses are collapsing as the engine cools, or there’s a sweet coolant smell after driving, a tired expansion tank cap is a common and inexpensive fix. Always open the cap only when the engine is fully cold, and replace caps with genuine or quality-equivalent parts that meet the specified pressure rating and seal profile.

• Maintenance tips: inspect the cap seal for cracks or flattening, make sure the threads engage smoothly, and replace the cap at the first sign of pressure loss or staining around the tank neck.
• Coolant choice: use the Ford-approved coolant type and concentration listed in the owner’s manual, typically a premix or a 50/50 blend with demineralised water.

Popular questions about a 2006 Ford Transit “radiator cap”

Where is the radiator cap on a 2006 Ford Transit?
There isn’t a cap on the radiator. The system uses a pressurised expansion (header/degas) tank with a screw cap. Look for the translucent plastic coolant bottle in the engine bay—it’s the cap on that tank, usually marked with a yellow warning symbol.

What pressure cap does a 2006 Transit use?
Many 2006 Transit variants use a cap around 140 kPa (about 20 psi), but always match the rating to the sticker on the tank or what’s listed for your exact engine code. Using the wrong rating can cause coolant loss or sluggish warm-up.

How often should the expansion tank cap be replaced?
There’s no fixed interval, but it’s smart to inspect it at every service. Replace it if the seal is perished, the cap doesn’t hold pressure, or you notice recurring coolant smells and stains around the tank neck. It’s a low-cost part that prevents bigger cooling headaches.