Merc 25HP Lower unit Milky Oil

Bought a new (to me) used duck hunting rig.
Motor is a 1987, (called and checked with Mercury), serno 0B126929, short shaft 15", tiller drive, rope start.

Motor runs fine, starts one pull, idles great.

Checked lower unit oil, and when I removed plug, oil was milky in color. I used to own a 150HP, and remember from winterizing, this is not good.

I reserviced, with new lower unit oil.

Can I safely operate this motor?
What price wise should I expect to pay for a lower unit rebuild?
What price wise should I expect for a prop seal (?) rebuild?

Can I do these myself? Are there special tools required?
I am somewhat mechanically inclined.

Any help would be appreciated, I love duck hunting, and this is bumming me out, my last season of some free time before I retire from the US Navy. Hopefully it is something I can get squared away soon.

Appreciate all the advice

Chris

Re: Merc 25HP Lower unit Milky Oil

These are great motors and had a very long production run, 1980 until maybe a few years ago when 4 strokes took over.

I suggest getting a Mercury factory service manual off ebay or direct from Mercury. Also, very useful to get a Mercury parts list direct from Mercury.

I would rebuild the lower unit with new seals. You can get a lower unit seal kit, from Mercury, for less than $100. Hopefully the prop shaft seal surface and the drive shaft seal surface are not too worn.

The biggest obstacle will be getting the bearing carrier off. You can buy a tool for this, or I have made a number of bearing carrier removal tools from an appropriate sized piece of pipe and some sorta creative use of a hacksaw and files. A service manual will show you a picture of what this tool looks like which will help quite a bit.

Good luck!

(You might could get through duck season by changing the oil every trip, but as always, seals get worse and not better.)

Re: Merc 25HP Lower unit Milky Oil

The driveshaft seals are the most common cause of this type of leakage and are easily replaced since they're pressed into the lower water pump body.

I'd check this out first before tearing the lower unit all apart. If the propshaft seals were leaking, you'd find a puddle of oil on the floor after the motor sat for some time.

Here's a good place to find a parts breakdown for your motor:

http://www.mercruiserparts.com/SelectModelType3.asp?class_id=2

HTH..........ed

Re: Merc 25HP Lower unit Milky Oil

Thanks for replying to me. There is no oil on the deck after motor sits for extended periods. So, leaning towards Ed's diagnosis of the driveshaft seals.

Ed you say these are easily replaced? I have not a clue as of where to start to replace them. Can you, at your convenience of course, please give me the dummied down steps required to do this job?

Thanks for your time.

Chris