Water in lower unit

[stormyj]

Hi all,
I changed oil in my bravo 3 lower unit and found some water in it. Removed the drive and its sitting on my bench right now. Was going to put together a pressure test set to see where it is leaking. Heres where Im curious. where are the points that it can leak under water. Yes, I know, anywhere, i just want to know what seals and where they are located. Im sure the outer prop seal can leak, but where else can it leak and where should I just replace the seals to be sure I dont have a problem. After I replace any seals I will do a pressure check on it to ensure it is not leaking. Thanks for any help.

 

[crazy charlie]

With water intrusion a vacuum test would be the priority but pressure and vacuum should be done.Personally I would want to know which one is failing before I just went out and replaced all seals.Prop shaft seal is an easier one to inspect for leakage as it shows as straight forward to look at.Possibly something as simple as gear lube drain or vent washer/gasket.Charlie

 

[stormyj]

With water intrusion a vacuum test would be the priority but pressure and vacuum should be done.Personally I would want to know which one is failing before I just went out and replaced all seals.Prop shaft seal is an easier one to inspect for leakage as it shows as straight forward to look at.Possibly something as simple as gear lube drain or vent washer/gasket.Charlie

Im hoping for an easy fix. But that never happens. lol

 

[dubs283]

The only seals under water on a bravo are the propshaft seal(s)

Other seal area is the input yoke shaft which should not be subject to water at any time as the u joint bellows should be dry inside

Be sure the drain plug gaskets are in good shape and the shouldered area is free of debris/old gasket material

 

[stormyj]

The only seals under water on a bravo are the propshaft seal(s)

Other seal area is the input yoke shaft which should not be subject to water at any time as the u joint bellows should be dry inside

Be sure the drain plug gaskets are in good shape and the shouldered area is free of debris/old gasket material

After more thinking about it, my boat is in a slip so when it sits, the outdrive is pretty much all underwater. which means it can be leaking from anywhere. I would think that the only place where it is wearing down would be the shaft seals. all the other seals around are between two mated surfaces and shouldnt really be a problem after this long, a 2006 searay. There was no hit or anything and last time I changed the oil, there was no water.

 

[stormyj]

So heres my next question. If I change the shaft seal, do a pressure/vacuum test on it, and find no leaks, is it safe just to refill it with 90w gear oil, or should it be flushed with something? Will any remaining water that might be left in there be a problem? Fill, run, and change oil again? Just curious. Realistically, I would think the whole thing needs to be torn down, inspected, and put back together.

 

[dubs283]

If the u joint bellows are dry inside and in good shape with no gear oil present you can rule out the yoke shaft seal

The drive halves mate with o rings so little chance of the leak being there unless there is damage from a hard strike or corrosion

Mercruiser has a service bulletin about bravo 3 propshaft seals leaking lube and has re designed the seals to correct the issue. If you are not having to constantly add lube to the monitor bottle you may be okay but water in the lube indicates a pretty decent leak somewhere and should be fairly obvious, seal or otherwise

 

[stormyj]

If the u joint bellows are dry inside and in good shape with no gear oil present you can rule out the yoke shaft seal

The drive halves mate with o rings so little chance of the leak being there unless there is damage from a hard strike or corrosion

Mercruiser has a service bulletin about bravo 3 propshaft seals leaking lube and has re designed the seals to correct the issue. If you are not having to constantly add lube to the monitor bottle you may be okay but water in the lube indicates a pretty decent leak somewhere and should be fairly obvious, seal or otherwise

How much play should there be between the joint drive shaft and the prop shaft? When I twist the shaft it turns maybe 10 or 15 degrees. Seems loose sloppy. Link to video.