60930 Exhaust Water Shutter Flapper Stops Water From Backing Up Into the Motor Compatible with MerCruiser 4 Cylinder and Jackshaft V8

GHMarine exhaust water shutter (rubber flapper / check valve) for MerCruiser sterndrive applications that use OEM reference 60930. Typical catalog uses: 4-cylinder packages, V8 jackshaft routing, and Quick-Change thru-transom exhaust tip families. It sits in the exhaust path to help block seawater from washing back toward the manifolds (hydrolock risk on reverse, following seas, or steep ramp launches). This is NOT 807166A1 / 807166A3 / 99370A2 / 807166A2.

What is this part?

A rubber exhaust water shutter (flapper / check valve) referenced as OEM 60930. It helps keep seawater from washing back into the exhaust path. Package: 1 × shutter.

Signs yours needs replacement

• Cracked, missing, or stiff rubber flapper — seawater can wash back on reverse or steep launch

• Fragments of old rubber found in the Y-pipe / exhaust tip when you open the path

• Hydrolock worry after reverse or ramp launch — shutter is one of the first checks

• Discovered during water-pump or bellows service when the exhaust tip/hose is already open

• Old part stamped 60930 or cross-ref 18-2727 / 65930 / REC60930 / 9-42800

Transom bellows leaking at the drive? Different part family (e.g. 17B1003) — not this shutter.

Will it fit my engine?

Horsepower alone does not prove fit. Match the old part number / exhaust routing. Catalog context: 4-cyl · jackshaft V8 · Quick-Change thru-transom tips using 60930. Verify serial before order. *Years from aftermarket catalogs — confirm SN.

OEM & swap numbers

Replaces ref 60930 · cross-ref 18-2727 · 65930 · REC60930 · 9-42800.

Wrong shutter? Read before you order

• NOT 807166A1 — 4in Y-pipe shutter (GH SKU 17ST002 / pair 17ST003)

• NOT 807166A3 — offset / center-rise (GH SKU 17ST004 / pair 17ST005)

• NOT 99370A2 — 3in Y-pipe (GH SKU 17ST006)

• NOT 807166A2 — one-piece GEN+ manifold (GH SKU 17ST007)

• NOT 18-2732 / 18-2733 — different shutter families (not 18-2727)

• NOT 843434A2 / 843426A2 — tip baffle repair kits, not shutter 60930

What's in the box

• 1 × Exhaust water shutter (60930 equivalent)

• Hose clamps / tip hardware — only if shown in product photos (sold separately otherwise)

Related GHMarine SKUs

• Need 807166A1 (4in Y-pipe)? → GH SKU 17ST002 (single) / 17ST003 (pair)

• Need 807166A3? → GH SKU 17ST004 / 17ST005

• Need 99370A2 (3in Y-pipe)? → GH SKU 17ST006

• Need 807166A2? → GH SKU 17ST007

Installation overview

• Confirm the removed part or service manual shows 60930 / 18-2727 family before install.

• The shutter itself is simple; access and a stuck exhaust hose are usually the hard parts.

• Upper-tip applications are often DIY; older bottom-exit / round-pipe setups may need more labor.

• Inspect the mating hose and tip while open — replace hose if cracked or glued solid.

• Do NOT use bellows adhesive / expander tools meant for transom bellows — this is a flapper, not a bellow.

• If your old part is 807166A1/A3 or 99370A2, stop — order the matching GH SKU instead.

Frequently asked questions

Is this the same as 807166A1?

No. This listing is OEM 60930 / cross-ref 18-2727 for 4-cyl / jackshaft / Quick-Change tip families. 807166A1 is a different 4-inch Y-pipe shutter (17ST002).

Can I run without the shutter?

Short calm-water runs may feel fine, but reverse, following seas, and steep ramp launches raise seawater backflow / hydrolock risk. Replace a cracked or missing flapper promptly.

Does this fit my 5.7L MerCruiser?

Only if your exhaust routing uses the 60930 family (often jackshaft / specific tip packages). Many V6/V8 Y-pipe boats use 807166A1/A3 or 99370A2 — verify the old part number.

What's in the box?

One exhaust water shutter (single piece). Tip repair kits and hose clamps are separate unless shown.

Do I need bellows adhesive or an expander?

No — those are for rubber bellows on the transom. This SKU is a water shutter flapper inside the exhaust tip path.

Please note

Aftermarket replacement part. Not affiliated with engine manufacturers referenced above. "Compatible with", "Replaces ref", and cross-ref numbers identify fitment — always confirm with your serial number and old part number before ordering.