32-44348T Upper Exhaust Bellow 4 Inch Transom Tube Seal for MerCruiser Alpha One Gen I/II, Bravo and MCM 4.3–7.4L V6/V8 sterndrives

GHMarine upper exhaust tube for the 4-inch by 4-inch upper exhaust path — the rubber tube between the exhaust pipe and the inner transom plate, inside the engine compartment. Catalogs list it as an upper exhaust tube; many bros call it an upper exhaust bellow — same part, both names.

Ships as one upper exhaust tube; hose clamps included when shown in product photos. This is a clamp-on part — bellows adhesive and expander tool are not needed.

Which bellow is this?

This is the 4" UPPER exhaust tube at the inner transom plate — not the large bell-housing boot outside the transom (8M0124227 / 17B1003), not the riser elbow-to-Y-pipe boot (32-14358T / 17B1001), and not the 3" lower tube (32-90949T / 24B1052).

If you are not sure, open the engine hatch and compare the part number molded on your old rubber, and measure the diameter — this one is 4 inch at both ends.

Signs yours is due

·       Louder exhaust or a raspy tone under the engine hatch at idle — splits and loose clamps on the 4" tube between the exhaust pipe and the inner transom plate show up as sound first.

·       Water in the bilge while running — this tube carries water-mixed (wet) exhaust, so a split dumps cooling water straight into the bilge on the engine side. Bilge pump cycling more than usual after a cruise? Trace the exhaust rubbers before blaming hull fittings.

·       Exhaust smell or fumes under the hatch — an in-hull exhaust leak can push carbon monoxide into the engine compartment. Treat any exhaust smell aboard as replace-now, not next-season.

·       After an overheat event (failed impeller, blocked raw-water intake) — hot dry exhaust cooks the rubber: glazed, hardened, or bubbled surface. Replace the upper tube even if nothing has failed yet.

·       Seasonal check: black soot at the joints, cracked rubber, rusty clamps — replace on schedule. Water pooling at the transom outside usually points to U-joint, shift cable, or bell-housing boots (17B1003 side), not this tube.

Will it fit my drive?

Engine horsepower alone does not prove fit. Match serial numbers in the table.

Application	Years	Serial / check point	OEM ref	Notes
MerCruiser Alpha One Gen I / II	1983–present	Gen I: S/N 06225577 thru 0D469858; Gen II: 0D469859 and up	32-44348T	4" upper exhaust tube at the inner transom plate
MerCruiser Bravo One / Two	1988–present	Bravo SN 0B664190 and up family	32-44348T	Same 4" upper tube on Bravo exhaust path
MerCruiser MCM 4.3 / 5.0 / 5.7 / 6.2 / 7.4L V6/V8	1983–present	Engine-family application; verify serial and removed part number	32-44348T	Covers most compatible MerCruiser 4" sterndrive exhaust paths
MerCruiser Blackhawk	1996–present	High-performance segment; verify serial before order	32-44348T	Same 4"x4" upper tube family

 

OEM & swap numbers

Current OEM is 32-44348T — the same tube also appears as 32-44348001 and legacy 32-44348 (three generations of one part number). Common interchange refs: 18-2748, 89120, 9-72805.

Type	Part Number	Notes
OEM	32-44348T	Current part number — 4"x4" upper exhaust tube
OEM	32-44348001	Same part, factory catalog numbering
OEM	32-44348	Older numbering before T suffix — same tube
OEM ref	0775485	Legacy reference seen in aftermarket catalogs
Cross-ref	18-2748	Interchange — replaces 32-44348T
Cross-ref	89120	Interchange — replaces 32-44348T
Cross-ref	9-72805	Interchange — replaces 32-44348T
Cross-ref	9-72807	Tube exhaust variant listed against 32-44348T

 

Wrong part? Read before you order

The 4" upper tube sits in the most mixed-up corner of the exhaust family — four near neighbours share the same area. Match diameter + position + part number:

·       Not for the transom bell-housing exhaust bellow 8M0124227 / 18654A1 — that is GHMarine 17B1003 (outside the transom; drive-off job with adhesive).

·       Not for the 4" riser elbow-to-Y-pipe bellow 32-14358T — that is GHMarine 17B1001 (upstream on the exhaust path, at the manifold riser).

·       Not for the 3-inch lower exhaust tube 32-90949T — that is GHMarine 24B1052 (smaller diameter AND different position).

·       Not for the 3" upper / 3"-to-4" tube 70981A3 — that is GHMarine 17B1014 (check the diameter of your old tube before order).

What ships in the box

·       1 × 4" upper exhaust tube (32-44348T family)

·       Hose clamps when shown in product photos

·       Not included: bellows adhesive, expander tool, bell-housing / riser / U-joint / shift bellows

Often ordered with the other exhaust rubbers

·       Riser elbow-to-Y-pipe bellow — GH SKU 17B1001 (ref 32-14358T), the 4" boot upstream of this tube.

·       Bell-housing exhaust bellow — GH SKU 17B1003 (ref 8M0124227 family), outside the transom.

·       3" lower exhaust tube — GH SKU 24B1052 (ref 32-90949T) when your drive runs the 3" path.

·       Many owners replace all exhaust rubbers and clamps in one service while the hatch is open.

Install tips — 4" upper tube at the inner transom

Factory service literature: the engine does not have to come out, but the exhaust elbow may have to be removed for access. No sterndrive removal, no adhesive, no expander tool — this is a clamp-on job. Work with the exhaust cold.

What you need

·       Hose clamps (included when shown) · flat screwdriver or nut driver for clamp screws

·       Wire brush or sandpaper to clean rust and scale off the metal exhaust stubs

·       Spray bottle with dish soap mixed in water — helps slide stiff rubber; avoid petroleum grease on the exhaust path

Basic steps (per the factory sequence)

1. Loosen the bellows clamps, then remove the hose clamps on the old tube at the exhaust pipe end and the intermediate / lower pipe end.

2. Remove the intermediate exhaust pipe if fitted, then remove the old tube. Cut it away if seized.

3. Wire-brush both metal stubs and wipe clean. Wet the stubs and the inside of the new tube with soapy water; soften stiff rubber briefly in hot water.

4. Reassemble with clamps placed over the tube before seating it; make sure every clamp is contacting the exhaust elbow, upper pipe, and lower pipe, then tighten securely and evenly.

5. Run at idle on muffs or in the water; check for exhaust noise or leaks at both joints. Re-check clamp tightness after the first heat cycle.

Not the transom bell-housing bellow (17B1003). Bellows adhesive and expander tool 91-45497A1 are for transom / drive-off jobs — not this clamp-on upper tube.

FAQ

My old rubber measures 4" at both ends — is this the one?

Yes, if it sits between the exhaust pipe and the inner transom plate: 4"x4" upper = 32-44348T, this SKU. If either end is 3", you need 70981A3 (17B1014) or the 3" lower 32-90949T (24B1052) instead.

Do 32-44348T, 32-44348001 and 32-44348 all fit the same?

Yes — three generations of one part number, same tube. Any of them molded on your old rubber confirms this listing. Cross-refs 18-2748, 89120, 9-72805 match too.

Some drives run a bellows here, some a straight tube — which is right?

Factory service literature moved V-8 drive-shaft-extension models from an exhaust bellows to a tube: back pressure can balloon a bellows into the U-joint boot and chafe it through. If your old part here is a tube, replace with a tube — this one.

Can I change it with the boat in the water?

Usually yes — it is an engine-bay clamp-on job: no drive removal, no adhesive, no expander tool. Let the exhaust cool first; the exhaust elbow may need to come off for access, per the service manual.

How do I confirm fit before ordering?

Match your drive or transom serial to the table above and the number molded on the old rubber. Horsepower alone is not enough.

What comes in the box?

One 4" upper exhaust tube; hose clamps when shown in photos. No bell-housing, riser, U-joint or shift bellows.

Please note

Aftermarket replacement part. Not affiliated with engine manufacturers named above. "Compatible with", "Replaces", and cross-ref numbers mean this part is built to work like the originals listed — always confirm fit with your drive serial number.