45497A1 Bellows Expander Tool Fits MerCruiser Alpha Gen II and Bravo Sterndrive

45497A1 Bellows Expander Tool — Fits MerCruiser Alpha Gen II and Bravo Sterndrive Bellow Service, Replaces 91-45497A1, 18-9847, 90360, 9-79811

Stretch the boot open. Exhaust bellows are usually the tightest fit on transom jobs — this steel bellows expander (spreader bar) hooks the rubber and holds it open while you seat the hose clamp. Replaces OEM 91-45497A1 and cross-ref 18-9847, 90360, 9-79811, REC91-45497A1. Compatible with MerCruiser MC-I, R/MR, Alpha One Gen II, Vazer, Bravo One/Two/Three, and Blackhawk sterndrives — confirm your drive tag before order.

Some Bros call this tool essential for the second hose clamp on exhaust bellow installs. It does not press the aluminum retainer sleeve — that step uses sleeve install driver 21B1001 / 91-818162.

Before you begin

Remove the sterndrive first. You need clear access to the gimbal housing and bell housing exhaust opening. Apply marine bellows adhesive to both boot ends and let it tack per the adhesive instructions (Sierra 18-9031 cross-ref family is commonly used with 18-9847 expander installs).

How to use this tool

1. Install the new bellow on the gimbal housing flange with adhesive.

2. Hook the expander and stretch the rubber through the exhaust opening in the bell housing — the tool holds the boot open so your hands are free.

3. Start the hose clamp while the tool keeps tension; remove the expander before final clamp torque (must-have for the second clamp).

4. Continue shift and U-joint boots per manual — exhaust is often last and tightest. Use sleeve install driver 21B1001 / 91-818162 for retainer sleeve seating where the manual requires it.

Not this tool

·       Sleeve install driver 91-818162 — seats retainer ring after bellow is on → GHMarine 21B1001

·       Sleeve removal tool 91-818169 — removes old sleeves (Sierra 18-9871 family)

·       Rubber bellow SKUs — kit 18BK003 or singles 17B1003 / 17B1007 / 17B1005

·       0901-3271008 / fuel pump legacy numbers — old catalog noise; not this expander tool

Interchange numbers & specs

In the box & commonly ordered with

Ships: 1 × steel bellows expander (91-45497A1 family) — tool only. No rubber bellows, marine adhesive, sleeve driver 91-818162, or removal tool 91-818169.

A full transom bellow job usually stacks like this — this expander is the clamp-assist step when rubber is tight, most often on exhaust, before you move on to U-joint sleeve work:

1. Bellows first. Three-bellow kit 18BK003 or singles 17B1003 (exhaust) / 17B1007 (U-joint Gen II) / 17B1005 (shift) if only one location failed.

2. Adhesive, then stretch. Glue boot ends per manual; when exhaust rubber will not clear the bell-housing opening by hand, hook this expander and hold tension while you start the hose clamp (Sierra: key tool for the second exhaust clamp).

3. Sleeve driver last on U-joint. After bellows and clamps are done, retainer sleeve seating uses sleeve install driver 21B1001 / 91-818162 — different tool, later in the sequence. Marine bellows adhesive sold separately.

FAQ

Is this the sleeve install driver (91-818162)?

No — that is GHMarine 21B1001. This tool is the bellows expander / spreader bar (91-45497A1) that stretches rubber through the bell-housing opening so you can seat hose clamps. The sleeve driver comes later on the U-joint boot.

Which bellow actually needs the expander?

Exhaust is usually the tightest — Sierra lists this tool as essential for the second hose clamp on exhaust bellow installs. Shift and U-joint boots may also need it when rubber is stiff; exhaust is the step most DIY owners stall on without a spreader.

Do I glue both ends of the bellow before using the expander?

Yes for a typical Gen II job — marine bellows adhesive on the boot ends per your manual (Sierra 18-9031 cross-ref family is commonly paired with 18-9847 expander installs). Let adhesive tack, hook the expander, stretch the rubber into place, start the clamp while the tool holds tension, then remove the expander before final clamp torque.

Can I stretch the exhaust bellow by hand without this tool?

Some owners force it with extra hands, but tight Gen II exhaust rubber often needs even spread tension through the bell-housing opening — that is what the 91-45497A1 bar does. Forum threads show buyers ordering 91-818162 by mistake when they actually needed this expander.

Do I still need sleeve driver 21B1001 and new bellows?

For a full transom service, usually yes — order bellows (kit 18BK003 or singles 17B1003 / 17B1007 / 17B1005), use this expander during clamp work, then use 21B1001 / 91-818162 where the manual calls for retainer sleeve seating on the U-joint boot.

Is 91-8M0096108 the same tool as 91-45497A1?

Many retail listings show 91-8M0096108 as a supersede or alternate catalog number for the same bellows expander family. Match your drive tag and service manual; this listing's primary OEM reference remains 91-45497A1 with cross-ref 18-9847, 90360, and 9-79811.

Please note

Aftermarket service tool. Not affiliated with engine manufacturers referenced above. Some retail pages also show 91-8M0096108 — treat as a supersede candidate until confirmed on your drive tag; primary listing OEM remains 91-45497A1.