nissan 8 hp water in lower unit

[maineiac5586]

Hi, I have a 90's nissan ns8 8 hp longshaft. It gets water in the lower unit. I replaced the washers on the fill and drain plugs. When i had the drain plug out I pressed my air compressor nozzle against the hole and pressurized the lower unit and did not find any seepage. anyone have any ideas where to start? I removed the prop but don't know how involved it is to replace these seals. please help, thanks

I am also confused how water is getting in but I don't see any external gear oil leaks? If water can get in why is the gear oil not coming out from the source of where the water is getting in? Hope that made sense.

 

[maineiac5586]

Re: nissan 8 hp water in lower unit

If someone can give me a step by step to replace the prop shaft seal please. Looks like I need to pull the prop, remove the 2 screws holding the housing behind the prop (bolts to the lower unit), then pull this housing off and bang out the seal from the inside out? sound right?

 

[pvanv]

Re: nissan 8 hp water in lower unit

Start with the Factory service manual (available from any dealer, including me). You will need to re-seal the LU, which means the driveshaft seal, lower wp housing gasket, prop shaft seal, and the most-overlooked shift rod o-rings. The seal kit is cheap, and available from any dealer, including me. You will lower the LU for that job. While in there, with the LU off, consider a new wp kit, if it's been a couple of years since that was refreshed.

 

[maineiac5586]

Re: nissan 8 hp water in lower unit

can you briefly walk me through where the shift rod o rings are? also do i need to disassemble the gears in the lower unit or do those stay where they are? I know it would help to have the manual I just want to get a mental picture before I go that far. Also, can you send me the details on how to purchase the seal kit from you thanks

 

[pvanv]

Re: nissan 8 hp water in lower unit

Not a problem...

Drain the LU.
Disengage the shift linkage by driving out the 3mm ss roll pin at the lower end of the rod coupler.
Remove the 4 bolts that attach the LU, and lower it.
Remove the prop, thrust bushing, and the 2 bolts that attach the prop shaft housing to the LU case.
Pull out the prop shaft housing (being careful not to lose the push rod in the end of the prop shaft.
Drive the prop shaft and gear assembly out of the prop shaft housing.
Remove the 4 bolts that retain the wp, and pull the wp apart.
Remove the retainer bolt for the shift bushing and pop out the bushing.
Remove the lower wp housing, and pull out the drive shaft. Don't lose the B pinion gear.

Then...

Replace the prop shaft seal, the drive shaft seal, and the gasket for the lower pump housing.
Replace the inner and outer o-rings in the cam rod bushing.
Install a new wp kit.

Then...

Reassemble and reattach the shift coupler; Refill LU.

You can drop me an email at the office: paul@obersheimersails.com, or call 716-877-8221 and either I (but I'm out of the office this week) or Charlie can help you.

 

[maineiac5586]

Re: nissan 8 hp water in lower unit

I removed the prop but the metal bushing (I believe the thrust bushing) is stuck

 

[maineiac5586]

Re: nissan 8 hp water in lower unit

any idea how to get this off? I tried putting screwdrivers behind it but it wont budge. This is the metal bushing found on the splines after removing prop. I assume this needs to come off?

 

[pvanv]

Re: nissan 8 hp water in lower unit

It is probably stuck due to some oxidation. Once you pull the prop shaft housing, you can drive the prop shaft out of the housing, and the bushing will come off as the shaft slides through the housing, seal and bearing. Use a block of wood as a cushion, so the hammer or mallet doesn't damage the threads on the shaft. If it's really corroded, it should be replaced, as it may crack. If so, consider the prop nut kit, which has a prop nut, cotter, and bushing all in one bag, for about the cost of the nut itself.