Lower Unit Still Milky

[loonmud]

1974 Evinrude 25HP lower unit seals, impeller, drain and fill screws & washers replaced. Still gets milky after 1 to 2 hours. Pressure test held pressure for Four (4) days. I am told it dosen't take much water to make it milky. Anybody know what my contuing problem is caused by?

 

[wilde1j]

Re: Lower Unit Still Milky

Have you done a vacuum test (with the LU empty of gear oil)? Unless there's a crack in the LU, you still have a leak. Did you replace shift rod seal, prop shaft seals (typically two back to back - see shop manual for correct orientation), and drive shaft seals? BTW, impeller and water pump has nothing to do with the LU integrity.

 

[rwise]

Re: Lower Unit Still Milky

bad bearings would do this also, they don't have to be completely failed, just loose. bent shaft would be another.

 

[loonmud]

Re: Lower Unit Still Milky

WildeOne: Shop said Vacuum (pressure?) test was done and held steady four (4) days. Three (3) seals were replaced, no cracks visible. rwise suggests bad/loose bearings or bent shaft - any way for a layman like me to check these without spending any more money?

 

[WillyBWright]

Re: Lower Unit Still Milky

A motor that old is likely to have grooves worn into the shafts where the seals rode. That'll cause leaks like that. Sometimes you can place the seals slightly shallower in the bores to let the new seals ride on truer surfaces. The best solution would be new shafts, but then there's the REAL world.

 

[michaelfbush]

Re: Lower Unit Still Milky

All replies are good stuff. Could also boil down to poor cleaning the first time around. It's true just a little water makes milk so if inside of needle bearing and other hiding places were not completely rinsed you could get more milk. Or if the new seals were drug over shaft splines they might pass vac/pres test due to sealing action of assembly greez but when used the greez washes out and water washes in. The later is slim but what else is left?<br />Bearing slop: Grab the shafts and and wigle back and forth and shine a bright light on the oil seals. You may feel ever so slight motion but you should see no motion in the shine of the light off the rubber of the seal next to the shaft. If the shine moves> bad bearings or bearing thrust sufaces.<br />Shaft bent: Also turn the shaft. you should not see the light reflected off the seals move. If the light reflected off the seals moves> bent shaft or pitted, dinged shaft at seal location.

 

[wilde1j]

Re: Lower Unit Still Milky

WillyB is probably on the right path. BTW, if you find a grooved prop shaft or drive shaft, there are very thin SS sleeves which can be installed to get the shaft diameter back to nominal. Speedi-Sleeve is one such product used in the industrial world which I've seen used to avoid replacing an expensive shaft.<br />See, for more info:<br /><br /> http://www2.chicago-rawhide.com/speedi_sleeves.htm <br /><br />BTW, a vacuum test is not a pressure test. It's a separate test with negative pressure. The seals must withstand both to keep water out.

 

[loonmud]

Re: Lower Unit Still Milky

Originally posted by rude50:<br /> All replies are good stuff. Could also boil down to poor cleaning the first time around. It's true just a little water makes milk so if inside of needle bearing and other hiding places were not completely rinsed you could get more milk. Or if the new seals were drug over shaft splines they might pass vac/pres test due to sealing action of assembly greez but when used the greez washes out and water washes in. The later is slim but what else is left?<br />Bearing slop: Grab the shafts and and wigle back and forth and shine a bright light on the oil seals. You may feel ever so slight motion but you should see no motion in the shine of the light off the rubber of the seal next to the shaft. If the shine moves> bad bearings or bearing thrust sufaces.<br />Shaft bent: Also turn the shaft. you should not see the light reflected off the seals move. If the light reflected off the seals moves> bent shaft or pitted, dinged shaft at seal location.

 

[loonmud]

Re: Lower Unit Still Milky

rude50:<br />Can the "bearing slop" and "bent shaft" tests be done without opening up the lower unit?

 

[wilde1j]

Re: Lower Unit Still Milky

Check for bent shaft w/ a dial indicator and rotate shaft in place. A few thousands of an inch is OK, but certainly not more than 0.005".<br /><br />BTW, did you inspect the prop and drive shafts for grooving when you had everything open?<br /><br />As WillyBWright says, this can and does happen, especially for the prop shaft where mono wrapped around the shaft can cut it and damage the shaft. AS he suggests, offsetting the seals slightly to get good metal can work.