Pressure tested gearcase, is ok, but oil still turns milky.

[johnm]

About a week ago, I changed my gearcase oil. Let it completely drain(overnight) and filled it up with good quality oil. I ensured everything was tight and I also put two new washers on the fill plugs. After I got back from the first outing(with new oil), I checked it and it was quite milky. So I took it to a reputable dealer and mechanic yesterday for them to pressure check. I just got a call from the dealer and they told me that they can't find any leaks in my gearcase! Any ideas? Mind you, I had purchased all the seals necessary as I was going to do it myself. Any clues?<br /><br />Engine is a 1979 55HP Evinrude.

 

[alcan]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Hi John<br /> Since you took this to the pro's, do you think they vacuume tested as well? Might want to ask. Maybe you just have to flush more of that old stuff out. That gear oil is fairly knarly stuff it doesn't come off too easy. Quite often a L/U will past one test but not the other.

 

[johnm]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Hi Alcan,<br /><br />Just called them. They say they don't have a vacuume tester and therefore can't run this test. They say the pressure check should pick it up and vacuume test not necessary. What next? Take it to somebody else who does have one? <br /><br />They did assure me that it should be ok, but I know L\U's can be expensive to fix and don't want to be paying big bucks later on!

 

[alcan]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Hi John<br />Not meaning to bash the shop, but it does make me wonder why they don't have this equipment. If it were me in this case, I would go to the auto parts or tool store and buy a vac pump tester. They are not very expencive and have many uses. Automotive testing, brake bleeding,the list goes on. I am sure if they said your L/U is good to go, it more then likely is. Most everyone I've dealt with in this business is a stright shooter. They like to be paid but they'er stright. How ever it never hurts to double check. Hec even I make mistakes.

 

[Solittle]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

John - You are on the right track by considering to take it to someone else. There are seals for the driveshaft below the water pump and shift rod that can also be candidate.

 

[ob]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

John,If you ran your motor one time and you got signs of water intrusion ,you got a leak.Pull the prop and do a close visual of the propshaft seal.If it is the culprit,many times, if water is leaking in that quick,some gear oil will be present.If it looks dry,I'm guessing your driveshaft seal or shift rod seal has failed.Other possibilities are the base gasket of the shiftrod bushing housing,or "o"ring on the propshaft bearing carrier.

 

[ledgefinder]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

How'd the fluid you originally drained look?

 

[johnm]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

It looked milky.

 

[clanton]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

The seals are double lip seals or double seals back to back. One seal holds water out, one seal holds oil in. Needs a vacuum test.

 

[johnm]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Can I do a vacuum test myself and how would I go about it?

 

[Link]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Hey John,<br />You are getting good advice here. Lower units need to be both pressure and vaccumed checked!I used to do both when working as a first service (mech) In a year I found 12 units which passed the pressure test but failed the vaccume test! All had milkly L/U oil! And these where new boats!<br />Keep up the good work PPL<br />Link

 

[dodge92]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Deffinitely have the vacuum test. I had a similar situation last year. Changed the lower unit oil, the old oil was milky white, and ran my motor on a flushing attachment to my garden hose. I checked the oil again and it was milky white. I had my service guy check it, and it pressure tested fine. It even vacuum tested ok, with just a slight leakdown. He decided the only way to find it is to disassemble the lower unit. It turned out to be the prop-shaft seal. Since he didn't have to do the whole lower unit, he only charged me for the one seal, lube, and labor, very inexpensive. FIND THE RIGHT MECHANIC AND HE WON'T STEER YOU WRONG. I have an 89 50HP Johnson still running strong.

 

[rwise]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

I had a unit that passed both vacuume and presure test (per the shop) and still leaked. What I found when I opened it was bad bearings!<br />Richard

 

[tmcalavy]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

bump

 

[alcan]

Re: Pressure tested gearcase, is ok, but oil still turns milky.

Yes John, you can do the test yourself. I think a hand vac pump kit goes for about $35. more or less. You can make an adapter from an old plug to fit your drain/fill hole. I use the end that comes with those little gear oil pumps. The ones you can buy or come with the gear oil bought from a dealer or marine store. Basicly just hook it up and draw vacuume to the specs, read the gauge,see if it drops. You can also turn the shafts by hand to try and cause failure. Just don't try too hard. Oh yea drain the oil first.