Gearbox on stern drive locked in FORWARDS gear

[ThePinkPanther]

Hi Guys, I'll try to spell this out real carefully as I have totally lost the plot myself!

I have a 1996 Ford Windsor 351 V8 short block running a Volvo Penta stern drive.

Following many dramas during the rebuild of this motor from the ground up it has nonetheless performed beautifully and never missed a beat for some three months.

But today not so! Started her up, slipped into REVERSE gear to back off my pontoon and lo and behold, it is actually in FORWARD GEAR, almost drove into my neighbours back yard.

So, in some sort of order I hope this clarifies the problem:

1. With the motor STOPPED there is UNRESTRICTED FWD and AFT movement of the throttle in the OUT OF GEAR POSITION (Pb on quadrant pressed to prevent gear engagement)

a) In this condition the propeller rotates freely in BOTH directions by hand

2. With motor STOPPED and GEAR SHIFT SELECTED there is only about 20 degrees of FWD travel available and far too much AFT travel movement - the throttle hits drivers seat)

a) In this condition the propeller jams when tuned by hand to REVERSE but if I rotate it FWD just a touch it will then rotate in REVERSE again very briefly but again lock up, over and over ........

3. With the motor RUNNING there is UNRESTRICTED FWD and AFT movement of the throttle in the OUT OF GEAR POSITION (Pb on quadrant pressed to prevent gear engagement)

4. With the motor RUNNING and GEAR SHIFT SELECTED to either FWD or REV the gearbox is irreversibly locked in FORWARD GEAR. Again the FWD travel is very limited as in 2) above but it screams it's head off in REV and
nothing can be done on the throttle to get it out of FWD gear! That's it, there's a better than average chance I have maybe missed a point above but hopefully it will provide a reasonably clear explanation of what is going on. None of the throttle or shift cable adjustments have been touched in any way or the gearbox itself, just happened overnight!

I think it's pretty obviously the throttle cable and linkages are fine and the GEAR SHIFT mechanism up inside the throttle quadrant appears to be also working OK as I can see the cable moving quite freely. I'd love to think it was just a linkage problem but I "did" hear a very brief noise in the gearbox "just once" that I didn't like the sound of but when it was charging away madly at anchor in FWD GEAR there was no sign of any "bad" noises! Yeh ..........!

Any advice appreciated and I'll do a double check on everything again tomorrow to make sure I have got it right, and my apologies if I haven't!

Thanks

Ian

[GBC]

We had a similar thing happen on a mates boat over at peel island. The cable popped out down in the gearbox. Easy enough fix but it had to come out of the water to do it. His jammed in forward but the engine could still start. Nearly hit the boat in front of us. If it had happened alongside it would have caused a bit of carnage.

[Noelm]

I guess the obvious thing to do is disconnect the controls altogether and operate the gears by hand at the engine end, at least that divides the whole system in half and will tell you if it's a control/cable/adjustment thing, or the gearbox itself.

[gofishin]

It sounds like you have checked/ruled out throttle/gear lever problems (in the mechanism itself), and as you state that nothing has been touched/worked on, that leaves 2 possibilities as I see it...

The gear selector cover is at the aft top section of the leg (behind the gear box). 2 x Phillips screws, bottom one has to come out, top one only needs to be loosened, then the cover comes off by pulling the bottom out first then slipping it downwards.

With this cover off, check that the cable and linkages are all fixed properly/not loose and split pins in place.

get someone to work the throttle/gear lever in fwd then reverse etc. Watch that the cable pulls and pushes the linkage and hence rotates the gear selector at the top of the leg.

If you see an issue, rectify as required. If not, keep looking... disconnect the cable & manually work linkage/selector.

If all this is working properly, the last possibility is what you don't want to hear! ($$$).

Oh, it's been over 20 yrs since I worked on Volvo legs, so I might be missing something too ! :)

[ThePinkPanther]

Thanks for the great reply! It's 2.30 am in Brisbane and my worry meter is on EXTREME but strangely enough your suggestion was my next step! I've had that cover off before to lubricate the linkages so once the sun is up that will be my first job! Problem is my 7.0 metre boat sits on an air-lifter to get it out of the water and working on the leg involves lying upside down on a plank, suspended over the water and of course dropping every tool, nut and bolt into the drink! But thanks again, just going to be a process of elimination. Cheers

[gofishin]

Do you have a ducky or a mate with one/a tiny? Park it underneath and work the right way up :)

[ThePinkPanther]

Hoping I've found the problem guys, disconnected the cable from the shift mechanism on the back of the drive unit and no problems selecting FWD or REV via that so would appear the cable has busted internally somewhere!

Just have to chase one up now, probably MORSE TELEFIX will have them and then thread it in somehow.

Thanks for replies!

[TheRealPoMo]

Tell us how it goes...I assume uou have a standard Volvo Penta throttle assembly. Mine could use a replacement.
How is the Holley BTW?

[ThePinkPanther]

Tell us how it goes...I assume uou have a standard Volvo Penta throttle assembly. Mine could use a replacement.
How is the Holley BTW?

Pretty easy to fit though getting the pull through wire round the corners is a bummer! Throttle and shift cables are both the same. Hydrive in Cleveland have a big range of the cables and adapters.

Carby redone again by another "expert", much better but still has to be primed with raw fuel before a cold start!

Cheers

[gofishin]

... so would appear the cable has busted internally somewhere!...If this is the case, you should see inconsistent movement with the cable at the gearbox - in relation to the movement at the gear/throttle lever. Confirm this before removing the cable.


...Just have to chase one up now, probably MORSE TELEFIX will have them and then thread it in somehow....Yep, Morse and an alternative which escapes me ATM - probably more alternatives now too.

Installing/replacing within the leg & feed assembly is pretty straightforward.

The AC/DC gear cable SS retaining plate has two small SS set screws, one in the centre & one outboard, opposite side to the cable. ONLY remove the outboard screw, loosen the middle screw and then skew/twist the retaining plate which will slip out of the cable groove. Fiddly, esp if you are 'planking' :). If you don't do this the cable ain't going nowhere.

To thread the new cable through into the leg, if it is hard to get through, loosen the clamp up the top of the cable hose inside the transom shield (this hose provides the waterproofing) . This allows you to wiggle the hose around a bit and makes it a lot easier to install the cable sometimes.

If you decide to dissemble the external linkages at the leg/g.box (for whatever reason) make sure the cable and vertical SS rod linkage goes back EXACTLY the same way. Accidentally swap them over and you will be going in the opposite direction to what you want to :)
Cheers

PS. Don't throw the old cable out. With some strong side cutters, cut thru the outer sheath one end, where the plastic sheath meets the SS outers. From the other end pull the inner cable out. This is HT stainless about 2mm in diameter. Great for all sorts of stuff.

[ThePinkPanther]

Thanks for all that advice, much appreciated!

I got the new cable off HYDRIVE just down the road at Cleveland.

But as you say, I'll have a play with the old one first to check it really has gone internally. Hate to yank it out and find it all in one piece! The inside transom attachment to the leg is so difficult to reach even a field mouse can't get to it ........

Hopefully this rain will stop me trying!

thanks again!