Volvo 120S-C shifting

[SJ28keith]

I bought a 10yr old, but still in factory crate, Volvo 2002 diesel and 120S-C saildrive and installed 2 years ago. All has performed flawlessly until now. Now, at 52 total hours, the 120SC will not shift into reverse on demand. Forward/neutral shifting is normal. Have confirmed that it is not linkage/shift cable problem, as shifter lever at saildrive housing is traveling to its limit. Last week, it slammed into reverse when some rpm was added. Yesterday I could not get it in reverse at all, so I pushed out of the slip and went sailing. During sailing, I put shifter in reverse position out of habit. Noticed that I could NOT hear prop spinning, suggesting it was in reverse. Started diesel with saildrive in reverse position and confirmed it was in reverse. Once shifted to neutral, it again would not go back into reverse on demand. Any ideas?


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[spannerman]

Sounds like you have a problem with the cone on the clutch, have you checked the oil to see if there is any contamination, looks like gold dust in the oil. remove the cable at the g.box and make sure when the gear lever is in nuetral and that the box is in nuetral, the cotter pin should line up with the hole in the arm on the g.box.ensuring you have equal throw.
If this is OK then I think you can remove the side cover holding the shift arm to inspect the mechanism, you will lose some oil, then you can check for free movement of the cone which should spin up and down on the vertical shaft, you maybe able to see the cone face when its up or down. If not or you can see particles in the gearbox then it has to come out to be repaired, if you are lucky it may be possible de-glaze the cone inside the gear, or at the worst you will need a new clutch. Good luck, Steve

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[PeterGibbs]

I defer to Spannerman's expertise on this but from my experience with the 120 drive, to put it into reverse whilst sailing with motor off will cause the gear to lock in reverse until the motor is started again. This appears normal and results in no loss of function.

What you describe seems to go beyond this. I have experienced damage to my drive through loss of oil, resulting in failure at the gear selector - I could not retain neutral. This required the box to be withdrawn and the selector mechanism rebuilt. If you have sustained such damage, through loss of oil or damage through contaminants, you most likely have a rebuild on your hands.

Sorry not to bring your more + news.

PWG

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[SJ28keith]

I appreciate the responses, but am a bit surprised by them. The model 120S drive I have is a saildrive, not a conventional stern drive. Does the 120S saildrive have a cone type clutch like a conventional stern drive? Since the saildrive looks similar to an outboard motor lower unit, I assumed it shifted in a similar manner and would not have a cone type clutch. My assumption may be dead wrong. In any event, the saildrive oil level was not low and the oil still looked new when I checked it. It occasionally shifts into reverse. When it does, it sounds and performs normally with no slippage. It only has 52 gentle hours use. I don't think the problem is wear. My sense is that something about the shift mechanism is sticking or is not properly connected. If it does have a cone type clutch, is there an internal adjustment of the "throw" each direction? Externally, the shift lever feels as if it is hitting a hard stop in both directions. These hard stops must be internal, however, because there is nothing external that would limit the lever's travel in either direction. Thanks in advance for any advise.

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[spannerman]

Yes Volvo saildrives use exactly the same system as the outdrives, a mechanical cone clutch. There is no internal adjustment the stop you can feel is the cone engaging with the cone in the gear, the only adjustment is on the cable and its imperative that neutral IS neutral otherwise its possible for the clutch to be nearer one gear than the other and so you don't get a positive engagement in one of the gears if its off center when in neutral. The simplest thing is to get someone on the helm to operate the shift and go down and remove the cotter pin, and manually engage the gear and get the helper to follow with the shift and check if the cotter lines up with the arm on the g.box thereby ensuring the cable has the correct amount of throw, a lot of control boxes have various mounting positions for the cable to suit different g.boxes. It should match up in all positions if not you will have to check the control box. Also you can run the engine while moored up and manually put it in reverse with the cable off, if it goes in everytime then your problem is external and therefore cheaper to fix!

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[SJ28keith]

Thanks for the response. Since my last post, I have obtained Volvo's workshop manual and been back to the boat. The 120-S saildrive has the exact same shifting mechanism as the various versions of Volvo's MS2 reverse gear. According to the workshop manual, the travel of the shift lever is limited by a steel pin hitting an internal machined surface in the shift lever assembly. While at the boat, I disconnected the shift cable and shifted from forward to reverse several times using only the shifting lever while the motor was running. It is clearly hitting the internal stops but only occasionally shifts into reverse. When it does, there is no slippage. So, it seems that the sliding sleeve that the shift mechansim moves up to engage forward and down to engage reverse is not engaging the reverse gear most of the time. What could cause this? Remember... it has only 52 hours since new, occasionally goes into reverse, never slips when it does engage reverse, and has new looking oil that has never been low. Is there anything I can do short of pulling the saildrive and disassembeling?

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[spannerman]

Hi Keith, I suggest you remove the gear shift cover and carefully extract the mechanism, watch out for the spring which will push the selector cam out of its hole in the shaft and note the offset as it only goes in one way ( the curved segment is off center to the clutch as you look vertically down on it) then when you have it completely out check it for wear, or stiffness, it should rotate freely in the hole as you operate the shift lever up and down, also check the running surfaces of the selector where they sit in the groove on the clutch for wear,self explanatory when you see it. You will lose some oil 1 liter? but its the only way if the boat is on the sea, just top up after assembly. As I said before if that seems OK then try to visually inspect the clutch by moving it up and down on its shaft, you may be able to inspect the exposed cone faces when its moved into forward and reverse ( up and down) If they are worn then its gearbox out I'm afraid, hope this helps, Steve

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[SJ28keith]

Thanks. I will try this procedure this Saturday or Sunday.

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[SJ28keith]

Spannerman and others: I think I found the problem and it is bad! I pulled the shift mechanism to inspect. The shift dog looked perfect, with no wear. I was able to reach in and move the sliding sleeve vertically until it touched the upper and lower gear. BUT.... then I noteced that I could put my finger under the upper gear and lift it up about .25 inches!! This isn't normal is it? I suspect the bearings are ruined.

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