Gasket, Lower Base – Fits Yamaha 75-90 HP Outboards (Replaces 688-45114-A1-00)
Gasket, Lower Base – Fits Yamaha 75-90 HP Outboards (Replaces 688-45114-A1-00) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
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.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This Gasket, Lower Base creates a reliable seal between the lower base and the engine block in Yamaha 75–90 HP, 2-Stroke outboard motors manufactured between 1984 and 2005. It is designed as a direct-fit replacement for the original component, ensuring proper function and preventing leaks.
It serves as a direct interchange for Yamaha part numbers 688-45114-A1-00, 688-45114-01-00, and 688-45114-00-00, as well as Sierra 18-99025 and GLM Marine 38033.
- Engineered for direct-fit installation.
- Constructed from a durable paper/composite material.
- Creates a secure seal between the lower base and engine block.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 688-45114-A1-00 | Supersedes 688-45114-01-00, 688-45114-00-00 |
| Yamaha | 688-45114-01-00 | Superseded by 688-45114-A1-00 |
| Yamaha | 688-45114-00-00 | Superseded by 688-45114-A1-00 |
| Sierra | 18-99025 | Aftermarket Interchange |
| GLM Marine | 38033 | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is compatible with a wide range of Yamaha 2-stroke outboard motors from 75 HP to 90 HP.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | 75A, 75AE, 75CETO, 75TLR, 75AED | 75 | 2-Stroke | 1984–2000 | 688-45114-A1-00 |
| Yamaha | E75B, E75MLHU, E75MLHT, E75MLHV, E75MLHW, E75MLHX, E75MLHY | 75 | 2-Stroke | 1994–2000 | 688-45114-A1-00 |
| Yamaha | P75TLHU, P75TLHV, P75TLHW, P75TLHX | 75 | 2-Stroke | 1996–1999 | 688-45114-A1-00 |
| Yamaha | C75TLRS, C75TLRT, C75TLRU, C75TLRW, C75TLRX | 75 | 2-Stroke | 1994–1999 | 688-45114-A1-00 |
| Yamaha | 80A, 80AE, 80AEO, C80TLRV | 80 | 2-Stroke | 1984–1997 | 688-45114-A1-00 |
| Yamaha | 85A, 85AED, 85AEM, 85AET, C85TLRP, C85TLRQ, C85TLRR, C85TLRS, C85TLRT, C85TLRU | 85 | 2-Stroke | 1989–1996 | 688-45114-A1-00 |
| Yamaha | CV85ELD, CV85ELF, CV85ETLD | 85 | 2-Stroke | 1989–1990 | 688-45114-A1-00 |
| Yamaha | 90A, 90ETN, 90AEO, 90AETO, 90ETLN, 90ETLK, 90ETLJ, 90ETLJ-JD, 90ETLH, 90ETLH-JD, 90ETLG, 90ETLG-JD, 90ETLF, 90ETLF-JD, 90ETLD, 90ETLD-JD, 90ETLDA | 90 | 2-Stroke | 1984–1990 | 688-45114-A1-00 |
| Yamaha | 90TJRP, 90TJRQ, 90TJRR, 90TJRS, 90TJRT, 90TJRU, 90TJRV, 90TJRW, 90TJRX, 90TJRY, 90TJRZ | 90 | 2-Stroke | 1991–2001 | 688-45114-A1-00 |
| Yamaha | 90TLR, 90TLRP, 90TLRQ, 90TLRR, 90TLRS, 90TLRT, 90TLRU, 90TLRV, 90TLRW, 90TLRX, 90TLRY, 90TLRZ, 90TLRA, 90TLRB, 90TLRC, 90TLRD | 90 | 2-Stroke | 1991–2005 | 688-45114-A1-00 |
| Yamaha | B90TLRV, B90TLRW, B90TLRX | 90 | 2-Stroke | 1997–1999 | 688-45114-A1-00 |
| Yamaha | C90TLRV, C90TLRW, C90TLRX, C90TLRY, C90TLRZ | 90 | 2-Stroke | 1997–2001 | 688-45114-A1-00 |
Technical Specs
- Product Type
- Lower Base Gasket
- Material
- Paper/Composite
- Installation
- Direct Fit
- Product Dimensions
- 10.0" H x 15.0" W x 0.25" L
- Weight
- 0.05 lb (0.023 kg)
- Function
- Creates seal between lower base and engine block
- Warranty
- Manufacturer Standard Warranty
What’s in the Box
- 1 x Gasket, Lower Base (Replaces 688-45114-A1-00)
Installation Notes
- Ensure the engine is off and cool, and disconnect the battery.
- Refer to your service manual to drain any necessary fluids.
- Remove any components obstructing access to the lower unit casing.
- Carefully detach the old gasket and remove any remaining material from the mating surfaces.
- Clean both surfaces meticulously with a quality gasket remover or appropriate solvent.
- Position the new gasket correctly. Do not use sealant unless explicitly required by your engine's service manual.
- Reassemble all components, tightening bolts to the specified torque in the correct sequence.
- Refill fluids, reconnect the battery, and run the engine to check for any leaks.
Troubleshooting & FAQ
How do I know if my lower base gasket is failing?
Common signs of a failed gasket include water contamination in the gear lube (milky oil), visible oil leaks from the seams of the lower unit, or engine overheating caused by cooling system pressure loss.
Is this the same as an "upper casing gasket"?
Yes, while some suppliers use the term "upper casing gasket," this part creates the seal for the lower base assembly. The definitive way to confirm fitment is to match the OEM part number 688-45114-A1-00 with your engine's parts diagram.
Should I apply sealant to this gasket during installation?
In most cases, no. This gasket is designed to create a seal on its own when installed on clean, flat surfaces and torqued correctly. Only use a sealant if your official Yamaha service manual explicitly instructs you to do so for this specific application.
When should this gasket be replaced?
This gasket should be replaced any time the lower unit is separated from the engine block for service or repair. It is a one-time-use part and should not be reused.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, 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 tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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