volvo 280 outdrive bubbles??

[bill56]

Hi, everyone, another one of those pesky volvo problems!! Have twin ford diesels driving 280 single prop legs (been in 13 years) with through transom exhausts - outdrive intake and exhaust bellows removed and blanked off (about 7 years ago I was told) so only top drive bellows and small bottom "L" shaped rubber tubes left (what are these for BTW?). Of course water intake grill at forward lower leg still open but doing nothing? The problem is difficulty engaging reverse on stbd engine- it clunks when put into gear- and on occasion lots of bubbles come up but no drive- bubbles increase with revs. This first happened coming bows to pontoon(Med birth), on stbd engine only, put engine into reverse(pausing in neutral) no braking effect only bubbles-therefore prop not turning- luckily port engine still running so avoided big crunch!! Please help!!

 

[ms1]

I have exactly the same config.
I think the bubbles may be a red herring I have seen some legs with what appears to be some kind of exhaust pressure relief/ equalisation (tube) which may be the source of the bubbles.
What you describe sounds like a 'cone' problem (except for one thing which I will come back to) . In these legs drive is achieved via cones which are a bit like 2 flower pots engaging one inside the other. Forward and reverse have their own cones. The cones do wear in time.
However - when they go it is not usual to get the engagement "clunk" .. it quietly engages and slips then after some seconds actually does engage and you have drive. Can be quite intermittent at first. Bit like a car slipping clutch in fact.
Engagement does require some hydraulic action between the cones so I am wodering if your oil level is too low.
The central screw on the top of the leg is the filler/ dipstick.
Too much oil is also undesirable as well.
I use a wheelie bin on the bow filled with water to get my stern up do so this sort of thing.
This is about the extent of my knowledge.
Here comes the scary stuff ...
New cones on one leg cost me £1,000 including lift out (Thames). The cones themselves costs several hundred pounds from Volvo.

 

[bill56]

Thanks for the speedy reply, will definitely check oil level even though both legs were done in July- you never know. I think you are right as if I leave boat unused for a while, I nearly always get bubbles on first engagement of reverse on this engine- when I try again a few seconds later it usually goes into drive- maybe oil has settled in leg and is moved around on first attempt, which gives some hydraulic action on next one- hence drive. BTW forward gear works perfectly on every try??!! Boat due to come out late November, so if no real damage is being done will just use port engine to stop for now. Thanks again.

 

[Grajan]

Unfortunately had a very similar problem which turned out to be cones. Volvo now supplied a modified replacement kit but still quite pricey