Bravo 1 air bubbles coming from top cover

[5at38off]

I cannot figure this out. It is a 2003 mercruiser 350 mag with Bravo 1 drive. after running 10-15 then stopping to swim you can see a stream of small air bubbles coming from the top plate. I have replaced the orings twice. there are no cracks. all surfaces are smooth and true to flat. after 5-10 minutes the air bubbles will stop. there is no water in the drive oil at all.. my oil bottle has not lost any oil. any ideas??

 

[alldodge]

I cannot figure this out. It is a 2003 mercruiser 350 mag with Bravo 1 drive. after running 10-15 then stopping to swim you can see a stream of small air bubbles coming from the top plate. I have replaced the orings twice. there are no cracks. all surfaces are smooth and true to flat. after 5-10 minutes the air bubbles will stop. there is no water in the drive oil at all.. my oil bottle has not lost any oil. any ideas??

Have you removed the back cover and if so what does it look like in the shift fork area?

 

[5at38off]

I have not removed the back cover. I can do so this evening, what would I be looking for?

 

[alldodge]

I have not removed the back cover. I can do so this evening, what would I be looking for?

There are two sections that the back cover seal, the upper gear set and the shift linkage. Your seeing bubbles and no water is getting into the gear section (good news) but it could be leaking from the shift cavity area. Otherwise I can see of no other place air could be coming from. The shift linkage area should be dry and only find some 2-4-c grease on the linkage.

 

[5at38off]

cool, I will pull it tonight and see what I find.

 

[5at38off]

2 things thats just weird with this, one the drive is completely full of lube and my reservoir is full so where can it be generating air from anyway. I have never seen this drive even get hot to the touch. second, with good surfaces and new orings how is the air getting by and no water getting in.

 

[alldodge]

2 things thats just weird with this, one the drive is completely full of lube and my reservoir is full so where can it be generating air from anyway. I have never seen this drive even get hot to the touch. second, with good surfaces and new orings how is the air getting by and no water getting in.

You have a strange one for sure and right now there is a very slight possibility it is coming from the other section somehow. It's either that or it's not coming from under the cap, may just look like it. Not saying your wrong, just trying to figure it out

Edit: BTW you need to remove some lube before you remove the back cover otherwise lube come flowing out

 

[5at38off]

so I ran it today for about an hour. with goggles on the air come out between the top cap and upper housing. I pulled the prop and pulled the drain plug and then went no futher. I had a small amount of water come out. about 3-4 seconds worth then the blue lube started to flow. so I must have a leak somewhere and when the drive gets warm air has to excape from somewhere. so is there a common seal that goes bad on a bravo? It is a 2003 model with 103 hrs. was run in saltwater most of its life..