Volvo Penta MS2B Gearbox clunk

[Marine Jim]

Please can you help? I have a Volvo Penta 2003 fitted with an MS2B gearbox. When either forward or reverse gear is selected there is a hard clunk. This was happening prior to me fitting new modified spline and driveplate. The clunk was less of a problem for the first few days. I suspect the cone clutch in the gearbox and I’d appreciate if anyone can offer any ideas.
Many thanks,
Marine Jim

[DougR]

All cone clutch gearboxes clunk to some degree when shifting into gear, it's just a question of how much. You might check the level and viscosity of the oil as that can effect the noise somewhat. Also, high RPM causes high clunk....the 2003 idle speed is recommended to be between 775 and 825 RPM. Set it as low as possible without vibration and dying when shifting, and that will help some.

It's possible that cone clutch wear is aggravating the situation some, particularly wear between the shift shoe and the groove in the center of the cone. If there is too much play here the cone isn't controlled well by the shoe, and can slam into gear.


DougR

[Marine Jim]

Dear DougR,
Thank you very much for your helpful reply. I can confirm that the oil level is ok and the oil has been changed this season. The oil type is as per engine oil and I wondered if a heavier oil might help. I will certainly start by reducing the engine revs as you suggest as she’s idling at 850 RPM. Since posting the enquiry, I’ve been wondering if the problem may partly be the 3 blade Variprop as it doesn’t appear to have any soft stops. I’m wondering if I should fit a fixed 3 blade prop and see if the slam is reduced. Do you think I should try say EP 90 oil in the box?
I really appreciate your help as there’s no substitute for knowledge and experience.
Many thanks again,
Marine Jim

[Paul L]

These transmissions have had a lot of issues with the spline. See this article
https://www.hisse-et-oh.com/system/a...pdf?1443112921

[Marine Jim]

Paul L
Thanks for your reply. The gearbox main splined shaft and splined drive plate have both been replaced prior to launching.
Many thanks,
Marine Jim

[Pete7]

Was this clunk there before you changed the drive plate and gearbox splines?

If not surely this is were the problem is?

The gearbox needs ordinary engine oil, I wouldn't put gearbox oil in if Volvo has specified a thinner oil, there will be a reason.

It could be the prop or even a rope cutter if one is fitted and the anvil hasn't engaged.

Pete

[Marine Jim]

Dear Pete7,
Thank you for your interest and reply. The clunk was present before the shaft and splines were changed. The gearbox oil is as specified by VP. I think the clunk could be caused by the cone clutch or the 3 blade Variprop which doesn’t have cushioned stops. I have reduced the idling speed which has helped reduce the clunk a little. I may have to temporarily fit a fixed 3 blade prop to eliminate the possibility of the Variprop being the problem.
Many thanks,
Marine Jim

[Pete7]

Jim,

My interest is because I have the same engine. You could just try taking the prop off and see what its like When they did my spline conversion, the gearbox input shaft was removed and changed to a hex instead of splines. There is also a Volvo solution which is slightly different but I haven't seen one.

However, since your problem existed before the change, it would be good to rule out the prop before tearing the gearbox down. They are getting expensive this side of the pond, £500 for a used one and no guarantees.

Pete

[Marine Jim]

Dear Pete7,
Thanks again for your help. Both the new shaft and latest drive plate are new VP parts. I agree totally with your suggestion that I check the Variprop before removing and dismantling the gearbox. The clunk wasn’t pronounced when I first launched in May and I suspect it may be due to the fact that the propellor hub was fully packed with grease which probably had an initial cushioning effect.
Many thanks again,
Marine Jim

[Marine Jim]

Dear Doug R,
I have reduced the tick over speed to 650 RPM and the clunk has been significantly reduced without the engine stopping or vibrating. The clunk is much lighter and I think I can live with it now. I note you say all cone clutches clunk to some degree. I would like to temporarily change to a fixed prop as I suspect the Variprop may be a contributing to the clunk.
Your help has been most useful and appreciated,
Marine Jim