HELP. Why my reverse gear behaves like this?

[cmedsailor]

I hope I manage to explain what the problem is!!
The engine is a Volvo Penta MD2030D and the reverse gear model is the MS10L. For neutral the level is in the middle position and then you push it forward a little bit to engage the gear (“click position”) and then of course forward for higher speed (rpm).
If from neutral position I push the level forward beyond the engagement position a little bit fast I often hear the reverse gear box spinning with no gear engaged. If I do it again but stop at the click position for very very little (less than one second) again sometimes the gear is not engaged. However if I push the level at the click position, leave it there for 1-2 seconds and then forward the gear will ALWAYS engage.
Is this normal? Is this how is supposed to work? OK, of course I don’t expect to change gears like a car and I don’t but on a few cases where I had to do a quick manoeuvre in the marina (cross winds, had to change from astern to ahead fast etc) the stupid gear didn’t engaged.

 

[morgandlm]

Ahead/astern

You keep referring to "the level" but I assume you mean the lever and that this is the morse control type lever in the cockpit. You do not explain where this is or what sort of boat it is so we must make a lot of assumptions.

If it is indeed a morse control type lever then it will probably be connected to the gearbox and the throttle quadrant by means of push/pull cables. These can be adjusted so that the movement of the lever, first engages gear, ahead or astern, then increases the throttle setting. If the cables or part of the mechanism get stiff due to poor lubrication or some other reason then problems can occur.

For what it's worth, on my boat going from ahead to astern or vice versa must be done fairly slowly with a pause in neutral or the transmission rotation is reversed too quickly which the system does not like.
Morgan

 

[SAMYL]

What sort of gearbox? (make & model) Ooops! Didn't read the question!

 

[david36]

If adjusting the cable does not work then I suspect that you have significant wear in the friction bands that in a car gearbox would be called the clutch plate. My marine engineering vocabulary does not extend to a precise term for such technical matters. However, having had a similar problem I recognise the features. Mine developed so that there was an increasing delay in selecting both forward and reverse. The solution is a significant rebuild by a gearbox specialist at a cost of £1,000 plus. When I raised the matter with Volvo a representative said that such a fault was "normal" after five or six hundred hours of use. I hope that I am wrong for the sake of your bank balance.
Good Luck.

 

[2Tizwoz]

Adjustment may be the cause but as the transmission works with wet clutches you may be not allowing the clutches sufficient time to properly engage and instead are causing them to slip. So stop it. You'll wear them out.

There's a free owners' handbook, which tells you that you should do it slowly, available on the Volvo Penta website (click here)

 

[Playtime]

Have you checked the oil level in the gearbox?

 

[oldharry]

Positive engagement of gears from neutral - every time, or you will damage the friction bands and possibly other components.

Pause to allow the engine to die down to tickover in neutral when moving from forward to reverse or otherwise, or again you will damage the box.

Check the oil level
Check the correct grade of oil has been used. Using 'gear oil' such as EP 80 or 90 when it needs ATX or engine oil, or vice versa can cause malfunctions such as this.

With a wet clutch system NEVER use a friction modifier additive such as Molyslip; they will cause all kinds of problems from clutch slip to complete failure.

 

[cmedsailor]

Let me add a few more things.
First of all, yes it is lever not level (sorry for my English).
The boat is a Beneteau Oceanis 361.
About a year ago my mechanic changed the discs inside the reverse gear box because he said that there were worn out (I bought the boat secondhand like this).
I never noticed that problem since that big maintenance (and big bill) until one incident 3 months ago after he increased idle rpm from 850 to around 1000 to have less vibrations. Could that affect it or was it just coincidence?
The oil grade is correct and is 3 months old (has only 2-3 hours on it because the boat was out of the water).
It gives me the impression that the clutches need a long time to engage otherwise they slip. Somebody called me that this is probably because the box has discs inside. Probably I will have to be more careful then (which I try but as I said in the beginning it was one of these rare cases where I had to make a fast manouvre. Faster thinking is probably my answer rather than faster movement!)

What are "wet clutches"?

Thanks

 

[oldharry]

Wet Clutches: In the car the clutch friction plate runs without lubrication. If oil gets to it, it will slip. Marine gearboxes may have to be able to work in the wet, so are built with the clutch inside the gearbox, and running in the gear oil. They may be plates, similar to those in the car, but more often are friction belts that run over the housing of a planetary gearbox . Planetary gearbox? A type of gearbox construction where everything revolves round a single central shaft using the clutch friction bands to engage fwd and reverse gears. Frequently used in boats because they can be built very compact with the output shaft in line with the engine crank.

Increasing tickover speed will affect the operation of the gearbox, and may well be the cause of your problem. Worth slowing the engine again to check and see if works properly. You then decide whether or not you can live with the disfunctional box, or have the vibes!

 

[SAMYL]

Have a look at this link, it describes gearboxes etc. in words of one sylable. If you can identify your type of box it will give you a better understanding of its operation and possible faults.

http://www.carbibles.com/transmission_bible.html

 

[Tranona]

Firstly, put the tickover back to the proper 850 rpm. If there is vibration at tickover, find the cause (possibly worn engine mounts?).

To check whether it is a selection problem or internal to the gearbox, observe the operating lever on the gearbox when the control lever at the helm selects gear. When the gear is selected the lever should move its full arc. You can check how far this is by removing the cable and moving the lever by hand. Do this with the engine off.

If the lever on the gearbox is not moving fully then adjust the cable. If it does move fully, but the gear does not engage than the fault is internal to the gearbox.

I have the same engine and box, although with a saildrive and it always goes into gear cleanly at tickover revs.