Transom Foam Gasket Seal 65533A1 65533 86712 for MerCruiser Alpha One R MR MC-1 1983-1990
Transom Foam Gasket Seal 65533A1 65533 86712 for MerCruiser Alpha One R MR MC-1 1983-1990
Product Overview
Transom foam gasket seal for MerCruiser Alpha One, R, MR and MC-1 stern drives built from 1983 to 1990, the foam seal that sits between the gimbal housing and the transom plate. It replaces MerCruiser 65533A1 and 65533 and crosses to GLM 86712, and it is one seal in an 18 x 15 x 3 cm bag.
The seal closes the joint where the gimbal housing bolts to the transom, and it is the part that stops water coming in around the drive rather than through the bellows. On an Alpha Gen 1 of this age the foam is usually flat and crumbly, and it is the one item people leave out when they rebuild the transom assembly because it looks unimportant next to the bellows.
A missing or flattened seal lets water into the bilge every time the boat is driven, and on a sterndrive that water reaches the gimbal bearing and the drive shaft before it reaches the pump. If your bilge pump runs after every trip and the bellows are sound, this seal is the next thing to check.
Specifications
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Transom and gimbal housing foam gasket seal |
| Fits | MerCruiser Alpha One Gen 1, R, MR, MC-1 |
| Years | 1983 to 1990 |
| Material | Closed cell foam |
| Net Weight | 94 g including packaging |
| Pack Size | 18 x 15 x 3 cm |
| Quantity | 1 seal |
OEM Cross Reference
| Brand | OEM Part Numbers |
|---|---|
| MerCruiser | 65533A1 |
| MerCruiser | 65533 |
| GLM | 86712 |
Compatible Engines
| Model | Type | Years |
|---|---|---|
| Alpha One Gen 1 | Stern drive | 1983 to 1990 |
| Alpha R | Stern drive | 1983 to 1990 |
| Alpha MR | Stern drive | 1983 to 1990 |
| MC-1 | Stern drive | 1983 to 1990 |
What's Included
| Component | Detail | Qty |
|---|---|---|
| Transom foam gasket seal | 65533A1 pattern | 1 |
| Bellows, gimbal bearing and transom plate | Not included, order separately | 0 |
Water in the Bilge on a Sterndrive
| What You See | What It Means | What To Do |
|---|---|---|
| Bilge pump runs after every trip | Water past the transom joint | Check the foam seal and the bellows |
| Water only when the drive is trimmed | Bellows or seal pinched | Inspect both before launching again |
| Rust on the gimbal bearing | Water reaching the bearing | Renew the seal with the bearing |
| Water in the drive oil | Shaft seal or bellows | Pressure test the drive |
| Damp carpet at the transom | Seal flattened or missing | Renew the foam seal |
| Boat sits low after a run | Slow leak past the transom | Dry it out, then trace the joint |
Alpha Gen 1 Transom Work
| Job | What Matters | Note |
|---|---|---|
| Bellows replacement | Renew the foam seal at the same time | It is destroyed by the old bellows coming out |
| Gimbal bearing | Check the seal seating on the housing | A twisted seal leaks from day one |
| Transom plate removal | Clean both faces before fitting | Old sealant stops the new seal seating |
| Corroded studs | Soak first, they snap in the housing | Order new hardware with the seal |
| Boat in salt water | Check the seal every few seasons | Foam goes hard and flat |
| Engine alignment | Alignment tool after the housing goes back | A misaligned housing leaks and eats couplers |
Fitting Notes
| Step | Action |
|---|---|
| 1 | Check the number on the old seal, 65533A1 crosses to GLM 86712 |
| 2 | With the drive and gimbal housing off, clean the transom face |
| 3 | Remove every trace of old sealant from both faces |
| 4 | Fit the foam seal dry, square on the housing |
| 5 | Check the seal is not pinched before the housing goes home |
| 6 | Torque the housing evenly in a cross pattern |
| 7 | Check engine alignment before the drive goes back on |
| 8 | Launch and check the bilge after the first run |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | Standard |
| Packaging | Sealed retail packaging |
Before You Buy
- Check the number on the old seal, 65533A1 and GLM 86712 interchange
- Fits MerCruiser Alpha One Gen 1, R, MR and MC-1 stern drives from 1983 to 1990
- Also listed as 65533 in some catalogues
- This is the foam transom seal, the bellows are not included
- Renew it whenever the gimbal housing comes off
- Water in the bilge with sound bellows usually points to this seal
- 30-Day Easy Returns
- Ships from our warehouse with tracking
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Boat Owners' Review
Before You Buy
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