I recently purchased a volvo penta engine MD 7A No 23739 with MS gearbox No 64324 At the moment its tied on a pallette (doing some work on it) as far as I know it as two reverse gears? One gear sounds fine (this drives the prop to the left) the other gear is making a whining noise, when its selected (this drives the prop right) is it ok to use this one as opposed to the quiet gear, to me the quiet one seems to be the forward gear? While the whining one seems to be reverse. The narrow boat that I have when that goes forward the prop turns to the right and then left for reverse is there any way I can change the MS box so I can use it in the quiet gear? ie: any conversion kits around, or anything that could be done inside the gearbox. the gear that whines might not last to long if and when I put it in the boat…………… is there anywhere I can get spares for this engine & box?
I am not familiar with a gearbox called an MD, unless it is the designation of a Volvo box. If so and Volvo-Penta agent should be able to obtain spares for you.
You description of how the box sounds tells me what you have inside it. In ahead gear, all the “guts” revolve as a single unit,
hence no noise. In reverse the drive goes through (probably) two or three parallel gear trains, each consisting of two gears (one double), plus the input and output gear. This explains the noise, and with this type of box is not unusual.
In general terms, the lubrication of the reverse gear trains is not usually adequate the ensure prolonged, reliable running in reverse gear – using it as ahead. The risk is yours, but I would not do it, marine gearboxes are expensive!
By far the easiest way of solving this problem is to fit the opposite handed prop, so from your description you need to swap your right hand one for a left hand one. In any case, a change of engine often indicates a change of propeller to obtain optimum performance – talk to Norris of Isleworth, Steel developments of Merton (I think) or Crowthers – possible Manchester. They should be able to advise on the correct prop size, matching engine to boat. Some suppliers will give an allowance against the old prop.
