Reinstalling bravo 2 outdrive questions

PickleRick

So im at the fun part.  The brilliant engineers at mercrusier used the same rear mounts on my 1000+ lbs diesel as they do a 3.0 4 cylinder.  So along with new bellows and gimball im addressing rear mounts.

Anyway, on an alpha you have a mounting gasket and the rubber ring around the input shaft bearing housing of the outdrive to seal the housing where the u joint bellow is.

On the bravo you have O rings but they are not around the u joint input housing, they are around the exhaust port, oil feed and shift cable.  What keeps the water intrusion out from where the drive meets the shield?  

Dream_Inn

I'm thinking a couple pictures here may help. Are you asking, where the actual drive (in bottom pic) bolts onto the middle pic...or the middle pic goes into the housing (top pic)?  I believe maybe you are asking about part #12 in the middle pic?

aero3113

@Dream_Inn , I think he’s asking what prevents water coming into the U joint/bellows area. 

PickleRick

The o ring kit in the bottom right corner box, none of that seals where the u joint bearing housing of the leg mounts to the shield

PickleRick

PickleRick

My question is, when I install the 6 nuts on the studs, what keeps water from coming between these two mated surfaces and allowing water into the u joint bellow. Do I coat the area where it meets at the base with bellow glue?

I don't have an outdrive water pickup so that o ring is a waste, where your water pick up hose goes I have an open water port to the shield away.  

Dream_Inn

I don't believe there is any sealant there.  I know positively that my drive has been removed, inspected, and then put right back on without any sealant added.  I do not remember seeing anything in between the drive and the plate it mounts to. I agree that does not make any sense.  I believe the mating part (shiny in your 2nd picture) seals within that rubber ring inside on your 1st picture.

Handymans342

Would it hurt to add a bead??

PickleRick

Looking at the outer bearing housing i see nice black paint.  This leads me to believe that all the time she sat in a Cali salt water slip that it never took in water between the mounting surfaces.

My reading leads me to believe the aluminum ring seals the two mating surfaces at the bellow.  I personally don't trust that aluminum ring. 

I think I'll but a bead of bellow glue around both the base of the mounting surface of the housing as all as the lip that mates to the bellow.


Does anyone else feel that bellow glue is expensive weather stip adhesive or rubber contact cement?  

PickleRick

Thanks @Willhound

I installed a new Sierra bellow.  I put a bead of bellow glue around the surface area where the input shaft housing lip meets the bellow ring.  

Luckily mercrusier designed the bravo where a 2x4 fits perfectly between the drive upper housing and the transom shield, a swift pull up with nuts out and trim cylinders removed will break the seal.  This is if you have the ability to firmly swing a 175 lbs outdrive back towards you. Im sure you know this trick  but maybe this will help a few first time DIY guys. 

On much of the new equipment we service both crank case sumps aka oil pans and valve covers use rtv rather than gaskets.  The better dead blow you can get the easier it is to remove.  

aero3113

@Alswagg , welcome back. Should we use bellows glue to help keep the O rings in place when installing the drive? Is grease better to use?

PickleRick

That's a good question.  Mine were held on with bellow glue but when I reinstalled I did so with grease holding them on as well as very well grease studs and splines.  It was difficult cleaning all the bellow glue out of the O ring recess.

I found people recommending both ways so I didn't know which was right.

aero3113

@PickleRick , I spent about an hour removing the bellows glue that was used by the previous owners mechanic. Grease would be so much easier for the next time.

PickleRick

Permatex makes a similar gasket maker/sealer and at one time so did loctite.  The stuff never hardens.  I have some of the loctie product from the GE turbine service shop dating back in the 90s and it's still comes out of the tube like it did back in 1996.  

GE usually got the good crap.  I'm pretty sure their duct tape could hold the wings on a space shuttle coming back into orbit.  The hand soap I got from there can both remove diesel oil stains from your hands and clog a sink instantly.   

aero3113

I bought some of the permatex aviation gasket sealer last season. I guess I can use a little of that.

PickleRick

aero3113 said:

I bought some of the permatex aviation gasket sealer last season. I guess I can use a little of that.

That's the Permatex equivalent.  

reneechris14

The nose of the Bravo is exactly 2 inches long. So after you set the bellows and the metal ring make sure to use a micrometer and it is less then 1.90. The drive seals to the rubber just out side the metal ring. So when you use the gorilla snot to set the bellows make sure it is in enough when you beat the rung in. 

reneechris14

Just looked at your pic, you have alot of material where the drive sits. I think if you put bead of something there it could be trouble to remove the drive in the future.