Ok fellas, I was gonna wait to get the boat out before asking about this but it's still in storage. Just haven't had the time to get changed over from winter workaholic mode to summer boater yet! When I put the boat away last year I changed the oil in my Bravo drive and the oil seemed a bit milky. I put a hand vacuum pump on it and it can hold 15 inches of vacuum for over a half hour. I spend a lot of time swimming around the boat and have never seen any hint of oil in the water. I'm wondering what you guys think my next move should be? Some say keep an eye on it and don't be too concerned yet, some say get the drive resealed. The moniter level never went up or down, the oil just looks like it got some water in it. Opinions would be greatly appreciated.
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Bravo drive gear oil getting milky
- Thread starter 502GTX
- Start date
yellowfiero88
Well-known member
I'm with Josh, cheap insurance to reseal.
yellowfiero88
Well-known member
IMO, the water got in there some way. It will get no better and only get worse till a failure of the bad seal. Unless the oil is checked after every run, 502GTX might not know of a major change of events with seal issue. At that point, we all know oil and water make a bad combo 
I had a issue with my SEI unit in the 2nd year of using it. Pressure tested great over 24hrs. Still let oil leak out and water in. SEI covered all repairs at no cost (except for my shipping to them) and also stated that they replaced some bearings due to pitting.
The cost of outdrives, the $400ish spent would be worth spending vs $2500+ for rebuilding it due to failure
I had a issue with my SEI unit in the 2nd year of using it. Pressure tested great over 24hrs. Still let oil leak out and water in. SEI covered all repairs at no cost (except for my shipping to them) and also stated that they replaced some bearings due to pitting.
The cost of outdrives, the $400ish spent would be worth spending vs $2500+ for rebuilding it due to failure
Thanks guys for all the input. Much appreciated. I attached the vac pump to the oil fill plug. I'm definitely not opposed to having it resealed, I just don't know who to trust around my area. I definitely know of a few shops not to trust. I just don't want the old "you need an all new everything" deal, once my outdrive is all apart. The cash ain't flowing like it once was, just want to be careful with it.
RNGRDVE
Well-known member
You may try refiiling with fresh fluid and a new fill plug. Since it holds vacc when tested at the fill port would make me believe that the plug is allowing some moisture to enter since that is the one item not being checked by your test. I would say fill, replace plug and monitor the fluid condition for a few runs to see if the problem is still present.
Philster
Active member
At a bare minimum, you need to do a trial run. Milkiness can show up quite fast; even a small am't of water will show a sign.
Get a look at the new oil. Heck... drain some perfectly fresh stuff from the drive and look at it. Take a picture. Take several. Top off the drive and head out for some time.
Take it back in after 30 mins and drain some oil. Even a little water will make a difference. Compare what you see with what you first sampled.
If nothing is wrong, try again.
Get a look at the new oil. Heck... drain some perfectly fresh stuff from the drive and look at it. Take a picture. Take several. Top off the drive and head out for some time.
Take it back in after 30 mins and drain some oil. Even a little water will make a difference. Compare what you see with what you first sampled.
If nothing is wrong, try again.
jazzy
Well-known member
Pressure tests are usually done over several hours not 30 mins and you're probably getting water in from the water passage inside the drive on thats why you aren't seeing a slick I'm pretty sure there's an o ring where the case splits around the passage but don't quote me I don't do my own drive work
Chris E
Well-known member
just to clarify - did you do a vacuum test or a pressure test, as they are two different tests. one will test the ability of the seals to hold pressure, the other tests the abiltiy to keep water from being sucked in. the seals are installed back to back, one seal can fail causing your problem. if memory serves (and it's been a lonnnnngggg time) here is what should be done:
pressure test at 3 and 15 psi, sometimes the high pressure in the drive can force the seal around the shaft makeing the leak disappear.
vacuum test - i think at the same pressures - i checked my alpha service manual it mentions nothing of either test, so, i'm not sure and i could be wrong.
both tests are performed at the vent hole, not the fill hole.
if it passes both, then i suspect your issue is the drive washers, which should be changed with every drive oil change. the other possibility is a bent propshaft, it doesnt need much of a bend to let water in.
did you take the prop off to check for fishing line - that'll take a seal out faster than anything.
hope this is of some help.
pressure test at 3 and 15 psi, sometimes the high pressure in the drive can force the seal around the shaft makeing the leak disappear.
vacuum test - i think at the same pressures - i checked my alpha service manual it mentions nothing of either test, so, i'm not sure and i could be wrong.
both tests are performed at the vent hole, not the fill hole.
if it passes both, then i suspect your issue is the drive washers, which should be changed with every drive oil change. the other possibility is a bent propshaft, it doesnt need much of a bend to let water in.
did you take the prop off to check for fishing line - that'll take a seal out faster than anything.
hope this is of some help.
Wow, a lot of great input guys thank you all very much. Chris, I did a vacuum check at the fill plug. I have not checked the prop shaft for runout, but the prop was whanged pretty good when I got the boat so I will be looking into it. I thought 1/2 hour was sufficient for a test but apparently not. I think as suggested above I will do another test at the vent hole, both pressure and vacuum. There doesn't appear to be any fishing line present. I am also thinking maybe I overlooked the o ring on the drain plug too as mentioned above. I want to check all the simple stuff before I take the drive in to be resealed but if I don't find a definitive answer to the problem I will have it resealed. Red, I changed the fluid at the beginning of last season with Mercury gear oil. The previous owner used high impact Redline synthetic. The oil in the drive had about 20 hrs on it when I noticed the milkiness in the monitor reservoir before I put it away last fall.
Got the boat into the shop and started checking it out. The prop shaft looks good, has between 003-004 runout measured at the flat area where the thrust washer seats. I did find something that looks like good news. The drain plug o ring looked OK to the eye (my deteriorating vision that is), but when I went to change it to a new one it crumbled in my fingers. I have installed new o rings on the plugs and added new oil to the drive. Gonna run it once, then if anything looks suspect, I will be having it resealed. I had my help, who is shorter than I am, squeeze into the engine compartment and change the impeller. Man is that sea water pump buried in a 251!