Lower Unit Seal Kit 93101-25M03 for Yamaha 40 70 80 100 HP Outboard
Lower Unit Seal Kit 93101-25M03 for Yamaha 40 70 80 100 HP Outboard
Product Overview
Lower unit seal kit for the Yamaha 40, 70, 80 and 100 HP four stroke outboards, the full set of seals for a gearcase reseal. It carries the oil seal 93101-25M03 and the O-ring seal 93210-86M39, plus the drain and fill plug gaskets and the two cotter pins, and it crosses to Sierra 18-4698.
Doing a lower unit properly means doing all of it at once. The oil seals on the driveshaft and the shift shaft fail from fishing line and from the prop hub, the drain plug gaskets fail from being reused, and the cotter pins get bent and refitted until they break. Change one and leave the others and the gearcase is back on the bench next season with water in the oil.
The two oil seals are the critical pair. They are a TC type, 25 mm by 40 mm by 6 mm, one on the driveshaft under the water pump and one on the shift shaft, and they are what keeps lake water out of the gear oil. When one goes, the oil turns milky and the gears start to pit.
The kit is built for one gearcase. Two oil seals, one O-ring, four plug gaskets and two cotter pins covers the whole job on a single lower unit.
Specifications & Attributes
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Lower unit seal kit |
| Oil Seal | Yamaha 93101-25M03, 25 x 40 x 6 mm |
| O-Ring Seal | Yamaha 93210-86M39, 5.7 mm section, 96 mm outside diameter |
| Drain And Fill Gaskets | Four supplied |
| Cotter Pins | Two supplied, 3 x 30 mm and 4 x 25 mm |
| Kit Number | Yamaha 604-45342-00 |
| Sierra Cross Reference | 18-4698 |
| Fits | Yamaha F40G, F70A, F80A, F80B, F100A and F100D |
| Engine Type | Four stroke |
| Parts In Pack | 9 pieces |
| Quantity | 1 kit |
| Net Weight | 40 g including packaging |
| Packaging Size | 150 x 180 x 40 mm |
| Packaging | Pack |
| Warranty | 3 year |
OEM Cross Reference
| Component | Part Numbers |
|---|---|
| Yamaha, oil seal | 93101-25M03 |
| Yamaha, O-ring seal | 93210-86M39 |
| Yamaha, lower unit seal kit | 604-45342-00 |
| Sierra, cross reference | 18-4698 |
93101-25M03 is the oil seal and there are two of them in the kit. 93210-86M39 is the O-ring seal, which sits on the shift shaft housing.
604-45342-00 is the Yamaha number for the complete kit and 18-4698 is the Sierra equivalent. Either one gets you the whole set rather than a single seal.
The drain and fill plug gaskets and the cotter pins are also in the kit. Their individual numbers are not published here, but they are the Yamaha parts that go with the same gearcase service, and the kit carries four gaskets and two cotter pins.
Compatible Engines
| Model | Horsepower | Engine |
|---|---|---|
| F40G | 40 HP | Four stroke |
| F70A | 70 HP | Four stroke |
| F80A, F80B | 80 HP | Four stroke |
| F100A, F100D | 100 HP | Four stroke |
Four model groups across the 40, 70, 80 and 100 HP four stroke range. The F80 and the F100 each come in two variants, A and B, and A and D, and both are covered by the same kit.
The listing gives model names and horsepower and no model years. Yamaha changed seal arrangements between builds on some of these models, so if your engine is an early or a late one, send us the model and the serial number off the transom bracket and we will check the kit against it before it ships.
These are the four stroke engines. The two stroke Yamaha 40 to 100 HP range uses different seals and is not covered by this kit.
What's Included
| Component | Part | Qty |
|---|---|---|
| Oil seal, 25 x 40 x 6 mm | Yamaha 93101-25M03 | 2 |
| O-ring seal | Yamaha 93210-86M39 | 1 |
| Drain and fill plug gasket | Included | 4 |
| Cotter pin, 3 x 30 mm | Included | 1 |
| Cotter pin, 4 x 25 mm | Included | 1 |
Nine pieces, which is the full set for one gearcase. The two cotter pins are different sizes, one for the propeller nut and one for the trim tab or the linkage, so check both against what came off your engine.
Key Features
| Feature | Detail |
|---|---|
| Oil seal 93101-25M03 | Two in the kit, 25 mm x 40 mm x 6 mm |
| O-ring seal 93210-86M39 | One in the kit, 96 mm outside diameter |
| Complete reseal | Oil seals, O-ring, four plug gaskets, two cotter pins |
| Sierra 18-4698 | The complete kit sold under the Sierra number |
| F40 to F100 | The four stroke 40, 70, 80 and 100 HP models |
| One gearcase | Everything for a single lower unit service |
Signs The Lower Unit Needs Resealing
| What You See | What It Means | Action |
|---|---|---|
| Gear oil turns milky | Water getting past the driveshaft oil seal | Fit the kit and pressure test the case |
| Oil on the prop or the skeg | Oil seal or the shift shaft seal leaking | Fit the kit |
| Fishing line behind the propeller | Line cutting the oil seal lip | Fit the kit before the seal fails |
| Gear oil level rising | Water ingress, seal already gone | Fit the kit and check the gears before refilling |
| Propeller nut loose or missing its pin | Cotter pin broken | Fit a new cotter pin |
| Gaskets flattened on the drain and fill plugs | Reused crush washers | Fit new gaskets at every oil change |
Fitting Notes
| Step | Action |
|---|---|
| 1 | Check the model and horsepower against the table above, four stroke only |
| 2 | Drain the gear oil and look at it, milky oil means the seals have already gone |
| 3 | Take the gearcase off and keep the driveshaft splines clean |
| 4 | Prise the old oil seals out without scoring the bore |
| 5 | Clean the seal bores and check them for corrosion and scoring |
| 6 | Fit the new seals square, with the lip facing the oil and a little grease on the lip |
| 7 | Fit the O-ring on the shift shaft housing and the four plug gaskets |
| 8 | Pressure test the gearcase before you put oil in it, a few psi is enough |
| 9 | Fill with gear lube, fit the cotter pins and bend them over, then check for leaks after the first run |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | 3 year |
| Packaging | Pack |
Before You Buy
- Lower unit seal kit for the Yamaha 40, 70, 80 and 100 HP four stroke outboards
- Oil seal 93101-25M03, two supplied, 25 mm x 40 mm x 6 mm
- O-ring seal 93210-86M39, one supplied
- Four drain and fill plug gaskets and two cotter pins in the kit
- Crosses to Sierra 18-4698, Yamaha kit number 604-45342-00
- Fits F40G, F70A, F80A, F80B, F100A and F100D
- 40 g with packaging, box 150 mm x 180 mm x 40 mm
- 30-Day Easy Returns
- Free Worldwide Shipping
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