30-803100T1 Transom Repair Bellows Kit Fits MerCruiser Bravo I II III & Blackhawk 1988 & Up

Full Bravo / Blackhawk transom repair kit — Compatible with MerCruiser
Bravo I / II / III (1988 & up, serial 0B664190 & up) and Blackhawk
(1994–95, serial 0F186717 & up). Bundles Bravo bellows, gimbal bearing,
16755A1 mounting kit, exhaust bellow + tube, water hose, and hardware so you finish
the whole seal job in one pass while the drive is off. Bravo U-joint is 86840A05 —
not Alpha Gen I 60932A4 or Gen II 816431A1.
Drive-off labor is expensive — replace the worn set together.
Bearing / mounting still solid → rubber-only 17B3003.

What is in the box?

Three bellows + exhaust tube + gimbal bearing + mounting kit + hardware for a complete
Bravo transom service. Each bellow also sold individually on GHMarine.com.

Component	OEM Part No.	GH SKU (single)	Qty
U-joint bellow (Bravo)	86840A05	17B1006	1
Exhaust bellow	18654A1 → 8M0124227	17B1003	1
Exhaust tube (454/Magnum/JackShaft)	78458A1	17B1015	1
Shift cable bellow	74639A2	17B1005	1
Gimbal bearing	30-60794A4	18MB001	1
Outdrive mounting kit	16755A1	—	1 set
Water hose	32-43437	—	1

 

Which kit is this?

OEM kit 30-803100T1 for Bravo / Blackhawk. U-joint 86840A05 is Bravo-only —
Gen I uses ridged 60932A4, Gen II uses flat 816431A1. Alpha drives →
17B3005 or 17B3007, not this kit. SN 1998+ → confirm greaseable bearing
(Mallory 9-72905).

Signs your transom needs service

·       Water in the bilge after launch — any of the three transom bellows may be torn or de-bonded.

·       Gimbal bearing howl or grinding when turning the wheel — bearing may be rusted or worn.

·       Oil weep at the drive mounting face — mounting gasket / O-rings in 16755A1 may be due.

·       Hard shifting — shift cable bellow may have pulled off its nipple.

·       Visible cracks, dry rot, or soft rubber on any bellow — replace the set while the drive is off.

·       Spring inspection or scheduled Bravo transom service — drive already off, do it all at once.

Will it fit my drive?

Bravo I / II / III 1988 & up. Serial 0B664190 & up. Blackhawk 1994–1995
(SN 0F186717+). Greaseable variant 1998+.
Match the drive serial plate — HP alone does not prove fit.

Brand	Model / Drive	Rated HP	Stroke	Years	OEM Part No.
MerCruiser	Bravo I / II / III	260–700+	4-Stroke	1988 & up	30-803100T1
MerCruiser	Blackhawk	300–415	4-Stroke	1994–1995	30-803100T1
MerCruiser	Bravo Greaseable (1998+)	260–700+	4-Stroke	1998 & up	30-803100T1 / Mallory 9-72905

 

OEM & swap numbers

30-803100T1 / Sierra 18-8219 / 18-8212 / GLM 21961 /
Mallory 9-72903 / 9-72905 / PROmarine 68396.

Type	Brand	Part Number	Notes
OEM	Mercury / Quicksilver	30-803100T1	Primary OEM — full Bravo/Blackhawk transom kit
Aftermarket	Sierra	18-8219	Transom Seal Kit Bravo I/II/III 1988+
Aftermarket	Sierra	18-8212	Alternate Sierra packaging — All Bravos
Aftermarket	GLM	21961	Transom Service Kit Bravo/Blackhawk
Aftermarket	Mallory	9-72903	1988–97 · SN 0B664190+ / Blackhawk 0F186717+
Aftermarket	Mallory	9-72905	1998+ greaseable bearing
Aftermarket	PROmarine	68396	Transom Service Kit Bravo

 

Wrong kit? Read before you order

·       NOT for Gen I kit 30-803097T1 — U-joint is 60932A4 (ridged); see 17B3005 (full) or 17B3001 (rubber only)

·       NOT for Gen II kit 30-803099T1 — U-joint is 816431A1 (flat); see 17B3007 (full) or 18BK003 (rubber only)

·       NOT a single bellow — this is the full kit with bearing, mounting kit, and hose

·       NOT 17B3003 — that is the rubber-only sibling (same Bravo bellows, lighter box)

·       NOT Gen I / Gen II U-joint (60932A4 / 816431A1) — Bravo needs 86840A05

What ships in the box

·       1 × U-Joint Bellows 86840A05 (Bravo type) with clamp

·       1 × Exhaust Bellows 18654A1 / 8M0124227 with clamps

·       1 × Exhaust Tube 78458A1 (for 454 / Magnum / JackShaft tube path)

·       1 × Shift Cable Bellow 74639A2 with clamps

·       1 × Gimbal Bearing 30-60794A4

·       1 × Outdrive Mounting Kit 16755A1

·       1 × Water Hose 32-43437

·       O-Rings & spare clamps as packed

·       Bellows adhesive — sold separately

·       Bellows expander 22ET001 — sold separately

·       Sleeve driver 21B1001 — sold separately (as needed per Bravo structure)

Install tips while the drive is off

Work in a ventilated area. If unsure, use a marine shop. Bravo drive removal = heavy — use a stand.

1. Remove Bravo sterndrive per shop manual. Drain gear oil. Use a stand — drive is heavy.

2. Scrape off old adhesive from all flanges — any crud left = future leak.

3. Apply bellows adhesive inside both ends of each bellow. Let tack up 10–20 min.

4. Install shift first, then U-joint, then exhaust last.

5. Use expander 22ET001 when seating the exhaust end onto the bell housing.

6. Confirm exhaust path: rubber bellow 18654A1 vs tube 78458A1 — do not mix paths.

7. Replace gimbal bearing and install 16755A1 mounting kit to torque.

8. Run on muffs in neutral, check bilge for water.

9. If SN is 1998+, confirm greaseable bearing (Mallory 9-72905 context).

Kit or singles?

Get this kit if: bearing howl / mounting weep / two+ bellows aged / planned overhaul while the drive is off.

Get a single instead if: only one boot failed and the rest + bearing are fresh —
17B1006 / 17B1003 / 17B1005 / 17B1015 (tube).

Sold separately either way: bellows adhesive · expander 22ET001 · sleeve driver 21B1001.

FAQs — the bros want to know

Will this fit my MerCruiser sterndrive?

Yes — for Bravo I / II / III 1988 & up (serial 0B664190 & up) and Blackhawk 1994–95 (serial 0F186717 & up). This is the FULL transom service kit. NOT for Alpha Gen I (17B3005) or Gen II (17B3007). Confirm your drive serial — horsepower alone is not enough.

What is in the box?

Bravo U-joint 86840A05, exhaust bellow 18654A1 (→ 8M0124227), exhaust tube 78458A1, shift 74639A2, gimbal bearing 30-60794A4, mounting kit 16755A1, water hose 32-43437, O-rings and clamps. Adhesive and tools sold separately.

How is this different from the rubber-only kit (17B3003)?

17B3003 = same three Bravo bellows only. 18B5001 = bellows + gimbal bearing + mounting kit + exhaust tube + hose + hardware. Bearing / mounting solid → 17B3003. Full transom service → 18B5001.

Should I buy one bellow instead of the kit?

Only one cracked and the rest + bearing are fresh → buy that single (17B1006 / 17B1003 / 17B1005 / 17B1015 for tube). Two or more aged, bearing play, mounting weep, or planned overhaul → 18B5001. Drive-off labor usually costs more than the missing pieces.

Do I need Gen I or Gen II kit instead?

Gen I 1983–1990 → 17B3005 / 17B3001. Gen II 1991+ → 17B3007 / 18BK003. Look at the U-joint: Bravo is 86840A05 only. These are NOT interchangeable.

Why are both exhaust bellow and exhaust tube in the kit?

Bravo applications use either a rubber exhaust bellow 18654A1 or a rigid exhaust tube 78458A1 (454 / Magnum / JackShaft path). The full kit packs both so you can match the path on your drive — confirm before you throw parts at it.

What about the 1998+ greaseable bearing?

Bravo drives from 1998 may use a greaseable gimbal bearing — Mallory 9-72905 is the catalog variant. Confirm the bearing you pull before ordering.

What tools do I need?

Marine bellows adhesive, expander 22ET001, and sleeve driver 21B1001 as needed for your Bravo structure. Gimbal bearing driver recommended. Shop manual strongly advised.

Please note

Aftermarket replacement kit. Not OEM. Not affiliated with engine manufacturers
referenced above. Always confirm fit with your drive serial
(0B664190 & up = Bravo; 0F186717 & up = Blackhawk).