changed seals, pressure tested, still milky - '98 25 hp Johnson

[renelson]

Aight, last month I noticed my LU oil was slightly water-tinged, so I decided to go ahead and change the seals. While I was at it, I changed the 2 prop shaft bearings and the top bearing on the drive shaft. Anyway, all the seals, gaskets and o-rings were changed.

I went out yesterday and checked the oil - milkshake. So, today I pulled the LU, put it under different pressures up to a max of about 15 to 20 pounds. No bubbles at all. I turned the drive shaft by hand in gear and still got no bubbles. The only thing I can't do is put it under a vacuum. Any ideas?

...the only thing I can think of is that when I put the prop back after I changed the seals, it didn't seem to go quite as far on the shaft as before. I noticed it because the rubber toothed washer that goes under the prop nut didn't slide down on the splines all the way like it used to. Maybe the line spool washer under the prop is resting on the seal.....I don't know..

Any advice? Think I'm going to just replace the prop shaft seal and see if that fixes it.

...and yes, the nylon drain plug washers are brand new.

 

[Bamaman1]

Re: changed seals, pressure tested, still milky - '98 25 hp Johnson

Sounds as if you need a marine technician to give you his opinion on the condition of your l/u.

The pressure and vacuum testing is not at high air pressure. To see if the seals are good, it's got to hold the pressure stable.

This is not something for a neophyte mechanic (like me.) And replacement lower units are some kind'a expensive.

 

[renelson]

Re: changed seals, pressure tested, still milky - '98 25 hp Johnson

Yeah, I'm definitely not a pro.

My service manual says to pressure test at 3 to 5 lb and if no leaks, go up to 16 to 18 lb. It held the pressures for 20 or 30 minutes no problem (and no bubbles).

The vacuum test, that I don't have the ability to do, might show a leak....

 

[renelson]

Re: changed seals, pressure tested, still milky - '98 25 hp Johnson

Just wanted to follow up on this post. I ended up replacing the two prop shaft seals (the same ones I replaced the first time only two months ago). I replaced them simply because they are the easiest to get to. Anyway, it seems to have fixed the problem. Went fishing yesterday and oil was fine afterward.

Thanks!