Lower Unit Leak

[ssanders14]

I have a 2004 Tohatsu 4-Stroke 30hp MSF30A engine. There is a small amount of Lower Unit Oil that I can leaks inside the prop after running the engine. There is normally a dime size pool around the outside edge of the prop. I know it is LU oil because of the smell. What part would need to be replaced to remedy this problem. Is it something that someone that is pretty good with their hands can do.

 

[walt-oxie1]

Re: Lower Unit Leak

It could either be the prop shaft seal or the o-ring that goes around the housing that holds the prop shaft housing to the lower unit housing. Both are fairly easy to replace.

 

[ssanders14]

Re: Lower Unit Leak

Any input from pvanv or Tohatsu Guru.

 

[pvanv]

Re: Lower Unit Leak

Walt is correct. A common problem on OB's is damage to the prop shaft seal from fishing line or other debris. The prop shaft seal can be replaced without dropping the LU. While other seals may be in question, in your case, the prop shaft seal is the likely culprit.

FWIW, we usually replace all LU seals at the same time, and throw in a wp kit as well on a 5 year old motor.

 

[ssanders14]

Re: Lower Unit Leak

I replaced the water pump less than 3 months ago. Should I get a lower unit seal kit? I don't have a problem dropping the lower unit. Are all the seals easy to replace without any special tools or knowledge. I have general knowledge and the water pump was very easy for me to do. It was the first time I had done it and it only took my about 45 minutes.

 

[pvanv]

Re: Lower Unit Leak

The seals are pretty straightforward to do. Don't forget to do the o-rings for the shift rod while you have the LU down. A seal pick comes in handy for getting the old o-rings out of the bushing.

Be careful when extracting the prop housing, so you don't lose the shift push rod or associated bits. Of course, drain the LU lube before disassembly, and keep everything "operating room clean" so no crud gets left inside the LU after reassembly.

Lubricate the lips of the seals and o-rings with a little LU lube when reassembling, to keep them from binding on the shafts. Also be sure that you insert the seals in the proper orientation (not inside out).

I'm not aware of a seal kit for this motor; Rather, they are individual parts. The factory probably could make up a new part number with all the seals in one kit, and they have suggested that they might, but if they have, I don't know of it yet. Check the parts catalog, available from any dealer (or online at http://www.internetoutboards.com/PartsCatalogMenu.htm) for specific part numbers, and orientation of the seals.