Yamaha F50 Outboard 100-Hour Service

The 100-hour maintenance service on a Yamaha F50 outboard motor only takes about half an hour to complete, and it includes changing out lubricants and filters. 

Watch the video above and follow the steps below to do a 100-hour maintenance service on a Yamaha 50 outboard.

Tools and Parts - Yamaha F50 Outboard 100-Hour Service

  • Ratchet and extensions
  • 14mm, 17mm sockets
  • Oil filter wrench
  • 1" hose or 1/2" hose with a barb fitting
  • Flathead screwdriver

NOTE: We performed the 100-hour service on a Yamaha F50 TLRA outboard motor, but the steps are the same or similar for most Yamaha outboards


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Yamaha 50HP Oil Change

Step 1. Remove the top cowling, and trim the motor up so the oil flows away from the drain plug.

Step 2. Remove the drain plug, which is located within a rubber boot at the rear of the motor just above the lower casing.

Yamaha F50 outboard oil drain plug

Step 3. Place a 1" hose over the rubber boot, or insert a 1/2" hose with a barb fitting into the rubber boot. Direct the other end of the hose to an oil drain pan.

Yamaha F50 outboard oil change service

Step 4. Trim the motor back down so the oil drains from the engine to the drain pan, then trim the motor up again, remove the hose and reinstall the drain plug. 

NOTE: If you're using the Yamaha oil change kit, fit the new crush washer included in the kit onto the drain plug before reinstalling it. Otherwise, you'll need to purchase a replacement crush washer for the drain plug.

Step 5. Replace the oil filter (see the oil filter replacement section below).

Step 6. Refill the motor with oil via the filler cap located at the upper rear of the motor. Check the motor's oil level using the dipstick located at the lower right side of the engine, just above the lower cowling.

Yamaha outboard engine oil change

NOTE: The Yamaha F50 TLR takes 2.22 quarts of oil.

Yamaha 50HP Oil Filter Change

Step 1. With the top cowling removed, trim the motor down to access the oil filter at the bottom of the engine on the left side.

Step 2. Lay a rag or towel under the oil filter to catch any oil that may spill out, then remove the oil filter with an oil filter wrench.

Step 3. Install a new oil filter without over-tightening it. 

Yamaha F50 outboard oil filter change

NOTE: The filter from the Yamaha oil change kit comes pre-oiled. If you're using an aftermarket oil filter, you may have to lightly oil the O-ring before installing the new filter.

Yamaha 50HP Gear Case Lube Change

Step 1. Tilt the motor up to access the gear case drain plug, located on the underside of the lower casing at the front.

Step 2. Place a drain pan under the gear case drain plug, and remove the drain plug using a flathead screwdriver. 

Yamaha outboard 100-hour service

PRO TIP: If the drain plug is difficult to loosen, use an open-end wrench to help turn the screwdriver. In extreme cases, it may be necessary to use an impact driver to loosen the drain plug.

Step 3. Remove the vent plug at the top of the lower casing on the right side, and let the old gear case lube drain out, then trim the motor back down to allow the old gear lube to fully empty out.

Yamaha outboard 100-hour service

Step 4. Connect a gear lube pump to the drain hole in the lower casing, and refill the casing with new gear lube. Continue filling the lower casing from the bottom upward until gear lube begins to flow out of the vent hole and there are no more air bubbles. This ensures there's no air left within the lower casing.

Yamaha F50 outboard engine 100-hour service

Step 5. Reinstall the vent plug, trim the motor up again, remove the gear lube pump and reinstall the drain plug.

Yamaha outboard F50 100-hour maintenance

Yamaha 50HP Fuel Filter Change

Step 1. Unscrew the fuel filter cup located at the back of the motor, being careful not to spill any of the fuel within the cup. 

Yamaha F50TLR fuel filter change

PRO TIP: If the filter cup is difficult to loosen, use a pair of adjustable pliers, but be very careful because the cup is made of plastic and can get damaged easily.

Step 2. Remove the old fuel filter element from the fuel filter cup, and pour the fuel from the cup into a drain pan.

Yamaha F50 outboard fuel filter change

Step 3. Install a new fuel filter and reinstall the fuel filter cup to the motor. Pump the fuel primer bulb a few times, and check the filter cup for any leaks. If there's a leak, tighten the cup further.

NOTE: If your boat is equipped with a fuel & water separator, replace it as well. When installing a new fuel & water separator, always pre-fill the separator with fuel before installing it, because a dry separator can make it difficult to prime the system once everything is back in place.

Yamaha 50HP Trim & Tilt Assembly Check

Step 1. Attach a grease gun to each of the zerk fittings on the trim and tilt assembly, and gently pump in new grease until you see it just beginning to squeeze out from the joints.

Yamaha outboard trim and tilt

Step 2. Trim the motor up to access the 17mm bolt in the trim and tilt mechanism.

Step 3. Have a rag or shop towel ready to catch any oil, and remove the 17mm trim and tilt bolt.

Yamah F50 outboard trim and tilt assembly

Step 4. Reinstall the bolt and you're done.

Yamaha 50HP 100-hour maintenance

NOTE: If oil begins to pour out from the bolt hole, that means the trim and tilt assembly is full. However, if oil doesn't drain out, top off the assembly with trim and tilt fluid first before reinstalling the bolt.


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