Transom Seal Repair Kit – Fits MerCruiser Bravo I, II, III, & Blackhawk (Replaces 30-803100T1, 8M0095485)

$105.00

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Transom Seal Repair Kit – Fits MerCruiser Bravo I, II, III, & Blackhawk (Replaces 30-803100T1, 8M0095485) is backordered and will ship as soon as it is back in stock.

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You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This is a complete Transom Seal Repair Kit – Fits MerCruiser Bravo I, II, III & Blackhawk Sterndrives (Replaces 30-803100T1, 8M0095485). It is designed for MerCruiser Bravo I, II, and III stern drives manufactured from 1998-onward (serial number 0B664190 and up) and Blackhawk stern drives from 1994–1995 (serial number 0D469859 and up).

This kit serves as a direct replacement for Mercury parts 30-803100T1 and 8M0095485, Sierra 18-8212-1 and 18-8219, and GLM 21965.

Installs in the stern drive transom assembly.
Features durable CR Neoprene bellows with stainless steel (SS304) clips and clamps.
Kit includes the essential gimbal bearing for a comprehensive overhaul.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury	30-803100T1 / 8M0095485
Sierra	18-8212-1 / 18-8219
GLM	21965

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For MerCruiser applications, verify your model and serial number range to ensure correct fitment.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
MerCruiser	Bravo I	All	All	1998–Present	30-803100T1/8M0095485	SN# 0B664190 & Up
MerCruiser	Bravo II	All	All	1998–Present	30-803100T1/8M0095485	SN# 0B664190 & Up
MerCruiser	Bravo III	All	All	1998–Present	30-803100T1/8M0095485	SN# 0B664190 & Up
MerCruiser	Bravo X	All	All	1998–Present	30-803100T1/8M0095485	SN# 0B664190 & Up
MerCruiser	Bravo XR	All	All	1998–Present	30-803100T1/8M0095485	SN# 0B664190 & Up
MerCruiser	Bravo Four S	All	All	1998–Present	30-803100T1/8M0095485	SN# 0B664190 & Up
MerCruiser	Blackhawk	All	All	1994–1995	30-803100T1/8M0095485	SN# 0D469859 & Up

Technical Specs

Product Type: Transom Seal Repair Kit
Installation: Stern Drive Transom Assembly
Connection: Stern Drive to Transom Assembly
Housing Material: CR Neoprene Bellows with Stainless Steel (SS304) Clips & Clamps
Housing Color: Black
Weight: 2.19 kg (4.82 lbs)
Warranty: Varies by brand - Sierra offers Limited Lifetime Warranty
Other Technical Attributes: Exhaust bellows design for Bravo/Blackhawk stern drives

What’s in the Box

1 x Gimbal Bearing
1 x Gimbal Housing Seal (41802)
1 x U-Joint Bellow (86840A3/86840A05)
1 x Shift Cable Bellow (74639)
1 x Bell Housing Exhaust Bellow (18654A1)
1 x Exhaust Tube (78458A1)
1 x Water Hose
1 x Gimbal Housing Oil Seal (16755Q1)
1 x Gimbal Housing Seal (41802)
1 x Insert Driver (41674)
1 x Lever (45518A3)
1 x Guide (43433)
1 x Insert (14705)
1 x Shift Cable Wrapping (38473)

Installation Notes

Disconnect the boat's battery and trim the sterndrive to the full "UP" position.
Remove the sterndrive assembly from the bell housing according to the manufacturer's service manual.
Carefully cut and remove the old U-joint, exhaust, and shift cable bellows, noting the orientation of the clamps.
Extract the old gimbal bearing from the transom assembly using a slide hammer with a bearing puller attachment.
Thoroughly clean all mating surfaces on the transom housing, removing any old sealant or debris.
Drive the new gimbal bearing into place using a proper bearing installation tool, ensuring it is fully and squarely seated.
Fit the new U-joint, exhaust, and shift bellows, securing them with the provided clamps. Ensure the clamps are tight and correctly positioned.
Replace the other seals and small components as included in the kit.
Reinstall the sterndrive assembly, taking care to align the U-joint driveshaft.
After reassembly, lower the drive and launch the boat, immediately checking for any water leaks around the new seals.

Troubleshooting & FAQ

How do I know if this kit fits my Bravo drive?

This kit is specifically designed for MerCruiser Bravo I, II, III, X, XR and Four S series sterndrives from 1998 and newer (serial number 0B664190 and up). It also fits Blackhawk drives from 1994–1995 (SN# 0D469859 and up). Always verify your drive's model and serial number before purchasing.

What are common signs that my transom seal needs replacing?

Key indicators include water intrusion into the bilge area near the transom, a roaring or grinding noise from the gimbal bearing when turning the wheel, or visible cracks, perishing, or brittleness in the rubber bellows.

Is a special tool needed to install the gimbal bearing?

Yes, professional installation is recommended. A slide hammer with a bearing puller attachment is required to remove the old bearing, and a dedicated bearing installation driver is needed to press the new one in straight without causing damage.

How often should transom seals and bellows be replaced?

As a critical preventative maintenance item, it is recommended to inspect bellows annually for cracks or wear. A full replacement is advised every 3-5 years, depending on factors like usage, saltwater vs. freshwater operation, and storage conditions.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It has been built to OEM-level specifications with comparable materials. The components are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free to most locations; expedited options will appear at checkout if they are available for your region.

Warranty & returns

This product is covered by a 1-year warranty against manufacturing defects under normal use. If any issues arise, contact our support team with your order details. Returns are accepted within our standard window provided the item is unused and in its original condition. Please see our policy page or reach out for instructions.

Safety & Important Info

Verify images and specifications against your original part before installation. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement part, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world reliability.
Fast Global Fulfillment — We offer free standard delivery to most regions with a typical transit time of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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