Buy Expansion Tank Coolant Cap (4596198)

The Expansion Tank Coolant Cap (Part Number 4596198) is a genuine OEM

cooling system cap used on many Chrysler, Dodge, Jeep and related vehicles. It’s often

referred to as a radiator cap, coolant reservoir hcap, pressurized coolant cap or

coolant recovery bottle cap in partshcatalogs, and is designed specifically to fit and seal

the coolant expansion tank (also called a coolant reservoir or overflow tank) on compatible models.

In an engine’s cooling system, the expansion tank helps manage excess coolant as it heats up

and expands during normal operation. The tank collects overflow and allows coolant to return

to the cooling system as it cools back down. The cap — while small and simple — plays a

critical role by sealing this tank and maintaining proper system pressure. It’s more

than just a lid: it’s engineered to hold a certain pressure so the coolant doesn’t boil

prematurely, and it helps keep contaminants out of the cooling system.

The 4596198 cap itself is typically

The 4596198 cap itself is typically made of durable materials designed to endure repeated

heating and cooling cycles. It attaches securely to the neck of the coolant reservoir, often with

an O‑ring or gasket to ensure a tight, leak‑free seal. When installed correctly, the cap helps

maintain optimum pressure inside the coolant circuit, which is essential to prevent

overheating and to keep the coolant flowing properly through the radiator and engine block.

This part is an OEM specification component — meaning it’s manufactured to the

original design standards set by the vehicle maker (Mopar for many Chrysler/Jeep/Dodge

models) and is often used as a direct replacement in maintenance and repair. It fits a wide

range of vehicles including, but not limited to, Jeep Patriot, Wrangler, Dodge Charger

, and other models within the 2001–2019 production years, depending on the engine and cooling system configuration.

Because the coolant system operates under pressure, a properly functioning cap like the

4596198 is crucial for engine health, performance and long‑term reliability. A faulty

or worn cap can lead to coolant loss, overheating, or air entering the cooling system — all of

which can accelerate wear and even cause serious engine damage if left unaddressed.

If you want, I can a vehicle fitment lists or explain how to test whether this cap is failing.lso give you