Sierra 18-4457 Exhaust Protector Valve, Replaces Mercury Marine 12644A1, 4 Inch EPDM

The Sierra 18-4457 Exhaust Protector Valve is a rubber flapper-style check valve built to keep water out of an inboard engine's exhaust system. It uses compounded rubber flapper valves that open to let exhaust flow out and close to block water from siphoning back in through the exhaust path when the engine is off or running at low speed. The valve body is made from weather resistant EPDM with a U/V stabilizer, which helps it hold up against sun exposure, heat cycling, and the marine environment better than untreated rubber. It is sized at 4 inches and ships with a stainless steel clamp, so the hardware needed to secure it in the exhaust line is included in the box.

This valve is built to the same fit, form, and function as the original equipment part it replaces and is designed to be interchangeable with GLM 89250, Mallory 9-44001, Mercruiser 13644Q01, and Mercury Marine 12644A1. It is commonly used on inboard exhaust manifold systems, including Chrysler inboard applications. Boat owners typically replace this type of valve when the rubber flapper becomes stiff, cracked, or no longer seals properly, which can allow water intrusion into the exhaust manifold or engine.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-4457
• Product Type: Exhaust Protector Valve
• Size: 4 inch
• Material: EPDM with U/V stabilizer
• Included Hardware: Stainless steel clamp
• Weight: 0.57 pounds
• Product Dimensions: 8 x 6 x 1.5 inches
• UPC: 030999621863
• Application: Chrysler Inboard Exhaust Manifolds

Fitment

Designed for inboard exhaust manifold systems, including Chrysler inboard applications.

Replaces (OEM)

• GLM 89250
• Mallory 9-44001
• Mercruiser 13644Q01
• Mercury Marine 12644A1

Frequently Asked Questions

What does the Sierra 18-4457 Exhaust Protector Valve do? It is a flapper-style check valve that lets exhaust gas flow out of the engine while blocking water from siphoning back into the exhaust system, protecting the manifold and engine from water intrusion.

What size is the 18-4457 valve? The Sierra 18-4457 is a 4 inch exhaust protector valve.

What material is the valve made from? It is made from weather resistant EPDM rubber with a U/V stabilizer, which helps the flapper valves hold up to sun and heat exposure in a marine exhaust environment.

Does the 18-4457 come with mounting hardware? Yes, a stainless steel clamp is included with the Sierra 18-4457 to secure it in the exhaust line.

Is the Sierra 18-4457 a genuine OEM part or an aftermarket replacement? The 18-4457 is a Sierra aftermarket part built to match the fit, form, and function of the original equipment valve it replaces.

Which OEM or other brand part numbers does the 18-4457 replace? The Sierra 18-4457 is designed to be interchangeable with GLM 89250, Mallory 9-44001, Mercruiser 13644Q01, and Mercury Marine 12644A1.

Is the Mercury Marine 12644A1 the same as the Sierra 18-4457? Yes, the Sierra 18-4457 Exhaust Protector Valve is designed as a direct interchange for Mercury Marine 12644A1.

How much does the 18-4457 exhaust valve weigh? The Sierra 18-4457 weighs 0.57 pounds.

What are the dimensions of the 18-4457 valve? The Sierra 18-4457 measures 8 x 6 x 1.5 inches.

What type of exhaust system is the 18-4457 used on? This valve is used on inboard exhaust manifold systems, including Chrysler inboard applications.

How do I know if my exhaust protector valve needs to be replaced? If the rubber flapper on your existing valve is cracked, stiff, or no longer sealing, water can enter the exhaust manifold; the Sierra 18-4457 is built to replace a worn valve with the same fit and function.

Is the Sierra 18-4457 discontinued? No, the Sierra 18-4457 Exhaust Protector Valve is an active, currently available part.