volvo penta msb gearbox

[zappa76]

Hi.

I've recently acquired a Volvo Penta msb gearbox. The previous owner stated that it was 'spares or repairs' as it was stuck in reverse.

Apparently it had been run with too low oil in it and the previous owner saw metal shaving in the housings.

I thought I would have a go at repairing this, re-paint it and get it working.

So today I downloaded the overhaul instruction manual and got going.
First thing I noticed is that there was some oil in there, very little, but it was very dark and I suspect very old. I cleaned it all up a bit and thought I would inspect everything. All the gears seem fine, bearings seem to turn ok without bad noises.

I've come across two pieces of definite damage and one that I'm not sure about.

In the front housing there is a little sleeve that is threaded, that is all mashed up (I'll add photos when I've worked out how to do that)
One of the bearings making up the reverse gear, seems to have a hole in the casing.

The bit I need help with identifying is the sliding clutch. On the outside there is wear to be seen, it also seems as if it has split in two, but isn't supposed to. following photos hopefully should illustrate what I mean.

I've read, that the sliding clutch could be one of the causes of the gearbox getting stuck In reverse, is that right?
This clutch is marked 827590. Unfortunately I can't seem to find a match, does anyone know the new number for it?

One last thing...how do I remove it?
Many thanks in advance.

[jimbunyard]

Can offer only a little help.

Oddly enough the the clutch still seems available, 827590 is the correct number. At about 900 euros, it hardly seems a viable choice though.

https://www.marinepartseurope.com/en...-44-13812.aspx



Given the damage to the clutch sleeve, I'd imagine item 52, the clutch dog, 3855602, which is apparently also still available, would need to be replaced as well.

As for the 'plug', which appears to be item 14, if it still serves it's function, looks like you'll need to reuse it as it's listed a NLA.

Can't help you with the hole.

I believe the clutch sleeve should just slide out. Perhaps it has become somewhat 'welded' or stuck into the gear, and some judicious force with a punch and hammer could free it up?...

The best solution may be to try and find another used 833558 gear and combine the two.

[zappa76]

Many thanks for the reply. I managed to release the clutch with a tiny bit of force. I definitely think this is the main problem here and the key to the repair.

I've also seen this part advertised by a European company for around the 900 euro mark, which as you say makes the whole thing not viable.

I'm wondering if Volvo Penta part 3807613 may do the trick though; I should imagine since the mid 70's when these things were produced, the part numbers have changed a couple of times, might be worth the gamble, still looking at £150 though.

The other option is to acquire a spares/repair ms/msb and hope the clutch is better than this one.

As far as the hole in the bearing case, that shouldn't be too difficult, as I can just replace the bearing there.

I've seen the little plugs advertised at around £30, so may invest in a new one, unless a great 2nd hand one crops up.

Thanks for the advice about the clutch dog, that wouldn't have occurred to me as the one I have looks fine

[DougR]

If you install a new cone clutch, it's a good idea to install a new shift shoe (clutch dog) as well. Use the old cone clutch and with some fine lapping compound remove any shiny glaze in the shift cups (gear side) and then reassemble with the new shift done. It's important to shim the shift shoe properly.....follow the instructions in the manual. This is what allows the shift shoe to pop the cone into neutral. If not shimmed correctly it will be difficult to get out of gear....forward or reverse.

The plug (#14) is in fact, just a plug to keep oil in the gear. Install a new O ring and reuse it. The threaded hole in it is so you can insert a bolt into it and pull it out.

The rear housing has two small roll pins, one of which seems damaged in your photos....these pins should protrude slightly above the machined surface of the housing. They engage the slots in the ends of the reverse idler gear shafts and prevent the shafts from rotating.

Don't see the bearing housing with the "hole" in it.....

DougR

[zappa76]

Thanks Doug, some great advice there. I can definitely do that if I am able to source a new clutch. Any idea if part 3807613 would work at all?

Are the two pins you mentioned easy to replace, ie pull out? How much should they be protruding out of the housing?

Sorry just to clarify, I shouldn't have said bearing housing, I just meant bearing, in fact if you look at the diagram put up by Jimbunyard, it is part 28. that is the one with the unusual hole in it.

Ok well that's good news about the plug, don't need to bother having that replaced and saves me £30!

[jimbunyard]

Well if these pictures are correct, no. Note the reversed helixes...

827590



3807613/380583

[DougR]

The roll pins shouldn't be too difficult to pull out if you can manage to grab them.....if they are dinged up it could be a different story.

They don't have to protrude much, just enough to pass thru the gasket
and fit maybe a millimeter into the slot in the end of the idler shafts.

Can't help much with the hole in the bearing race....I don't recall that..
Maybe a careful reading of the assembly instructions is in order.

DougR

[zappa76]

Thanks for the pictures.

So it would appear that my idea of chancing a 3807613/380583 replacement won't work as the helix is different to the older model.

It looks as if I will either need to source a MS/MSB spares repair or abandon the project for lack of the correct part.

checked the instructions and the hole to the bearing race shouldn't be there, so that needs replacing.

[boden36]

I have owned an MS gearbox on a 3 cyl Volvo and rebuilt it a number of times. Repowered with Yanmar due to the crappy box. Would not spend any money on one of these boxes!
Two main problems 1. the clutches were not long lasting: 2. The helix shaft has a circlip on one end to take reverse thrust which can pop off and you lose drive.
I did not treat the box roughly.

Regards,
Richard.

[zappa76]

Thanks Richard, it does appear as if this gearbox isn't worth repairing; as the correct clutch cone is approximately 800-900 euros to buy new, and a second hand one probably wouldn't last a long time.

I think I'll get rid of this and find a better project where the parts are easier to come by.

Thanks for your assistance. Regards Dean

[aquafacts]

If you need a complete MS box - let me know - I have several from fresh water applications - Gear ratio ?

[jag39]

Originally Posted by aquafacts

If you need a complete MS box - let me know - I have several from fresh water applications - Gear ratio ?

I ran across your comments. I've got a MD6A in need of a MSB box. Actually, the reduction gear housing is my problem, as the cooling jacket apparently rusted through, and when put in gear, pumps oil into the water. Having a problem locating either the reduction gear, or the complete works. My transmission is working fine, so far, but would buy complete unit in order to get the reduction gear/casing. This is 1.91:1.

Also, heard the MS2 could be used. Didn't know if this was true or not, so if anyone has information on this, it would be much appreciated. It seems most of them have a different ratio though.

[DougR]

Jag39,
You might be able to find an MS transmission reduction housing from a company called Capitol Equipment in Manchester, Connecticut. 860-643-7958.

Many years ago the New England VP distributor was a company called DiPietro-Kay. They sold many VP engines to sailboat builders in New England, and some of those engines were equipped with Walters V-drives. On these engines the reduction housing of the MS gear was removed and the Walters RV-10 V drive bolted in its place. At one time DiPietro had loads of the reduction housings sitting on the shelf.

Capitol Equip. is the corporate descendent of DiPietro and it might be worth your time to give them a call.

As far as the possibility of using an MS2 transmission behind an MD6..... It's maybe possible but would take some detective work to be sure. The MD6 engine morphed into the MD 7, and the last version of the MD7 used an MS2 transmission. This would require a variety of adapter components to make happen, and it's possible that the components used on the MD7 would not work with the MD6.

Even if it could be made to bolt up, the MS2 gearbox had two versions; a drop center/down angle output shaft, and a drop center/ horizontal output shaft. The horizontal output version had a drop center of about 2.6" compared to the drop of .75" of your MS gearbox. So your engine would have to be raised about 2" to get the gear box to align with the prop shaft coupling. Plus with all the adapter plates necessary for the MS2 gear, the package became about an inch longer so you would need to slide the engine an inch forward as well. Could this be done??

Perhaps it's better to stick with the MS gear....

DougR

[jag39]

Lots of information, and I really appreciate it. You pretty much verified what I was perceiving from pics only. One option I can check off.


I will try Capital Equipment, and see what they have to say.


Thanks again for the good info!

[Ngre]

Gents , interesting thread : can you help me
I’ve a Volvo MS box in my westerley which has started to leak oil from the prop seal - question can I just take off the rear housing part 73 with the box in situ ? and change the seal , rather than the whole box off - appreciate any advice thanks