Advice on Bravo 2 problem please

[nickscs]

Hi,
have removed bravo 2 leg from my Sealine to replace gimbal bearing, bellows etc, Its leant against garage wall . Noticed today it was weeping oil from the top plate seal. Due to the heat from the sun ??. In panic I checked the oil plugs top/bottom to see it had no water contaminant and luckily all was well, oil altho black was not milky and felt ok , no sign of water

I understand that these legs do pressurise (5-8psi) when warm in use , so question is ,apart from replacing the oil seal what else can i do to prevent this happening and what should the bolts be torqued down to?

Or anyone any ideas please? Help

Nick

[Jon Fuller]

Originally Posted by nickscs

I understand that these legs do pressurise (5-8psi) when warm in use.
Nick

No, unless it's a very early leg, (pre 88) they have an internal reservoir (within the boat) into which the drive can expand some of it's oil (as it warms) and draw it back in as it cools. So no pressure builds up, it vents into the internal reservoir (which is itself vented).

Not sure what you mean by leaking from the 'top plate seal'. The top bearing cap seals with an 'O' ring, so the only reason to leak from that area would be porosity, of corrosion, or maybe a crack.

Can you clarify the description of the leak.

[nickscs]

It was my local dealer (who usually knows his stuff) who told me that the leg pressurises and does not vent back into the lube tank on the engine, so not sure now.
However the leak is coming from the top plate seal, ie; the "O" ring. There are no cracks in either the top plate or the leg. The "O" ring does not seem to be damaged or nicked in any way, and the mating sufaces all "seem" to be flush and undamaged, but I shall check them for true later.
Also throughout the last 2 seasons the level in the lube tank has hardly dropped at all.

Its a `97 leg

[nickscs]

Originally Posted by nickscs

It was my local dealer (who usually knows his stuff) who told me that the leg pressurises and does not vent back into the lube tank on the engine,

However if you are correct that the oil vents back into the lube tank when warm, perhaps this explains why the "O" ring seal is leaking when the leg is warmed by the sun, as the pressure builds and cannot bleed away?
Or am I talking rubbish..... dont answer that.

[Jon Fuller]

Originally Posted by nickscs

However if you are correct that the oil vents back into the lube tank when warm, perhaps this explains why the "O" ring seal is leaking when the leg is warmed by the sun, as the pressure builds and cannot bleed away?
Or am I talking rubbish..... dont answer that.

I think that's a very valid point, as when you remove the drive, the wee spring & ball bearing assy closes off the passage to the remote reservoir to avoid oil loss, so it would indeed build up some pressure in the sun. ~However, it shouldn't leak, and if it did, I would expect it to be from a worn seal on a shaft or similar, not from the O ring where you describe, as that should be able to withstand pretty high pressures, and isn't subject to wear, or change.
I think a very close and detailed examination of that upper assy & cap is required.

The oil level in a Bravo is controlled by the position of the vent screw (fill level) and vertical position of the reservoir fitting (about the same elevation as the level plug). This is about 3-4 inches from the top of the drive upper housing, so a cavity should always remain in that upper part where only air resides (when not in operation) This cavity is all the early version had as an expansion area for the variations in temp etc before the reservoir version appeared, so even in the hot sunshine, the air gap in the top should be enough to allow the increased volume through expansion and stop any squeezing out of any oil when things get hot.

[nickscs]

Originally Posted by Jon Fuller

The oil level in a Bravo is controlled by the position of the vent screw (fill level) and vertical position of the reservoir fitting (about the same elevation as the level plug). This is about 3-4 inches from the top of the drive upper housing, so a cavity should always remain in that upper part where only air resides (when not in operation) .

When I removed the oil vent /level plug, the oil level was actually higher than this screw and lube tank connector.... so perhaps this "air cavity" had filled with oil... or would it anyway?

[nickscs]

Hi,
if anyone is interested in this, actually found the problem that on removing the top plate the little "o" ring over the gear shift shaft was not fitted correctly and was allowing oil to leak past. Have replaced this "o" ring and the main seal ring and this seems to have fixed the problem.

Cheers