Problem on 1997 Nissan 3.5B HP motor with lower unit

[OnAlert]

I posted this on the Mercury Forum first before I discovered the Nissan Forum.

Part number reference is: 2002 And Earlier M3.5B Tohatsu Outboard GEAR CASE (DRIVE SHAFT) Diagram and Parts

I have a 1997 Tohatsu 3.5B HP two-stroke engine. After rebuilding the water pump, I proceeded to pump gear oil into the filler hole. I was unable to see any oil exiting the "Level" hole. At a certain point, the filler hose mounted on the gear oil pump popped off with a degree of pressure, and oil was everywhere.

I showed the lower unit to my marine mechanic, and he tried to dislodge whatever was blocking the "Level" hole with an air compressor. The air compressor kept backing out.

He suggested removing the lower pump case assembly, which I have done.

The oil seal (#15, part number 3F0-60223-0/ OIL SEAL, 10 - 22 - 8) covers half the exit hole on the lower pump case that lines up with "level" hole on the lower gearbox housing.

Is this the correct position of the oil seal in the lower pump case housing?

I noticed that there was some water damage to the bearing (1-1,part number 9601-0-6000, BEARING, 6000).

Thought I would order new lower pump case assembly, new oil seal, pins, gaskets, and new #6000 bearing set.

Assuming the bearing set comes off the drive shaft on its lower end, I measured the distance from the bearing set to the lower end of the drive shaft, and measured diameter of drive shaft above the bearing set (.323") and diameter below the bearing set (.318").

I figured the "culprit" was the lower pump case, and thought I would just invest in new parts, but we're still scratching our heads for the solution.

Time is not on my side, I have to motor/sail my sailboat across the Neuse River & haul my sailboat out next Friday to paint bottom, and I would rather they lift the boat out of the water instead of off the trailer.

Any recommendations will be appreciated on my two predicaments, especially on removing the bearing set from the lower end of the driveshaft.

 

[Grub54891]

Re: Problem on 1997 Nissan 3.5B HP motor with lower unit

Is the seal in to far? It should not cover the hole. A pic would be good.

 

[pvanv]

Re: Problem on 1997 Nissan 3.5B HP motor with lower unit

Just re-seat the seal, or install a new one. It fits inside the lower pump case.

 

[OnAlert]

Re: Problem on 1997 Nissan 3.5B HP motor with lower unit

I removed the seal from the pump case, cleaned the "cup" (inside housing, the seal sets in) of the pump case, cleaned the oil seal, and reinserted it in the case. The oil seal still covers half the hole.

Picture a miniature of the USS Monitor having a hole in the turret pointed at the bow and one pointed off the port side. The holes in the turret are half open.

Maybe age has enlarged the seal. If properly seated, I assume the seal should remain below the two holes on the sides of the housing.

I will have to order a new oil seal and perhaps to be on the safe side, a new lower pump case.

Any comments on removing the bearing set from the drive shaft?

Thanks for your help.

 

[pvanv]

Re: Problem on 1997 Nissan 3.5B HP motor with lower unit

The seal must seat all the way into the lower wp housing, and not extend below it. No need to take the bearing off, unless the bearing is bad.

If a PO used something in the LU lube that damaged the seal, the other seals would be suspect as well... especially the o-rings for the shift rod, and the prop shaft seal. If the old seal is definitely distorted, consider installing a complete LU seal kit.

 

[OnAlert]

Re: Problem on 1997 Nissan 3.5B HP motor with lower unit

Decided to go for broke and disassembled the entire lower unit include shift rod & gears. The bearing on the driveshaft has to be changed sometime soon. Once everything is assembled, you can turn the drive shaft at top with your fingers, but sticks occasionally, which I attribute to water damage to the bearing, where I saw rust.

After complete reassembly, the "level" hole allowed gear oil to dribble out (hooray!), and after numerous attempts to get driveshaft inserted correctly & water pump tube aligned with water pump (frustrating, cause you can just barely see the tube "mate" with the water pump housing). After getting together and hooked up, she started right up and ran for about ten minutes until I turned off the gas **** at the tank to let the carb run dry.

I put the outboard on the sailboat today, and again, it started right up. Rather than "Mess with Texas", I decided to take a chance on the outboard woking for crossing the Neuse River on Friday. Not many here can say that their river is the widest in the USA; five miles!

What avenue of approach do you recommend in taking the bearing off the drive shaft when I do have to "Mess with Texas"? The drive shaft diameter is .005" larger above the bearing than below.

Thanks for all your help on this. Wish I had discovered this website a few years ago.

 

[pvanv]

Re: Problem on 1997 Nissan 3.5B HP motor with lower unit

You can use typical shop techniques (press, slide hammer, etc.) to get the bearing off, or you can buy a complete driveshaft with bearing for about $110 new, depending on whether you have L or S shaft.