No power in reverse

[Delaware]

Check the fluid and add ATF as needed. Be careful not drop the crush washer into the bilge.
Slightly low fluid = no power in reverse.
Additionally, if the boat has been sitting for a while without running the discs will stick together and cause lack of power. They will free up after you run them in gear for several minutes.

[Rumrace]

A Sea Drive 20 has cones not discs. Discs sticking together are in contaminated oil. When you add oil to a Sea Drive it’s leaking.

The 20’s cones can be resurfaced but the labour involved is so silly replacing the clutch pack makes more sense.
ZF inherited the design and repaired it with each generation. Their down side is the same as and transmission depending on water flow to cool it. This abuse running in neutral while the motor pretends to be a generator is hard on them. It makes the oil expand where there is no expansion available. This causes leaks and sucking water into the oil swelling and increasing leaks. One solution is to add a sealed expansion area which will not pull in water.

Sure it’s a control issue though

[FPNC]

Go below, disconnect the throttle and clutch cable from the engine and actuate both clutch and throttle by hand.

This will tell you whether you have a cable / control issue or a problem with the transmission or throttle.

[Cheechako]

Originally Posted by dbbd

One handle

Sounds like cable or problem in the shift mechanism to me. Those single lever systems go to neutral at idle lever position, when you go back it's not advancing the throttle. They are complicated little devices, but fairly easy to understand when out and in your hands. Something in the shift mechanism isn't moving the throttle only in reverse.

[HeywoodJ]

Originally Posted by dbbd

The metal tab say model ZF 30 H.
I have no idea what it is.

Is it coupled to a Yanmar 4JH series engine? Those were pretty standard on Sun Odyssey and come coupled to a ZF30M. Delayed engagement or no engagement on these transmissions is sometimes an adjustment of the shift lever cover plate. First step is always (as noted above) to disconnect the cable and shift by hand at the transmission. That determines whether the problem is inside the transmission or outside.

If you determine it is inside, the adjustment check and procedure are in section 7 of the service manual. I'd go through at least the check before digging any deeper into fluids, clutches, etc.

If you determine it is outside, well, that has been covered up thread.

[Rumrace]

Yes you’re absolutely correct the seadrives all generations are very dependable products. Could be helm control, cable, cable clamps,

[sailorladd]

The morse cable needs adjustment...

[Rumrace]

My Jeanneau SO is shaft but I’ve worked on a couple seadrives. They are typical ZF quality top drawer. They inherited the design and fixed it. My next Jeanneau I don’t believe is offered with one unless you spec it. Don’t see it on option list at any rate.
It’s hard work to pull the engine back but doable. Refinishing you Clutch is a temporary repair for a lot of work. They are all weak clutch designs compared to gas engine cone clutch. They have the advantage of grounding spark during shift to take the load off the shift.

[edlepera]

Transmission? Throttle and Gear level and cable issues? a missing key on the transmission shifting lever? lots of areas to explore.

[Southern Ocean]

I had the same problem with my Kiwiprop which feathers.
Took a long time but I think I have it sorted now.
In my case the torsion on the spring was to strong. I eased it a significant amount and now engaging and revving in reverse.

[wingssail]

OK, single handle control. You say it revs up when you push the handle either forward or reverse with the gear disengaged but it does not rev up in reverse with the gear engaged.

On many of these single handle control units there are some gears and cams behind the handle. These can wear or break and then not move the the throttle or, more often, not the gears.

I suspect that this is the source of the problem.

One way to confirm that it is not the transmission is to disconnect the throttle cable at the injection pump and operate the throttle manually as you shift the handle into fwd neutral rev. If you can make it rev up but the single handle control won't that is the problem, If however that does not eliminate the transmission, then you have a tranny issue.

[Cynara]

What happened when it failed

[GrowleyMonster]

I would first suspect the cable, linkage, or adjustment. That is a likely cause and is cheap and simple to fix. Always look at the stuff that is cheap and simple to fix, first. Isolate the problem by disconnecting the cable(s) and operating gearbox and throttle locally, tied securely to the dock with appropriate fenders out. If you get full power astern, then there is your problem. Check your main control cable for full and free movement. Try pouring a few drops of oil down the cable and working it, and see if you can free it up. Check the throttle linkage, and adjust appropriately.

Not the problem? Did you have full power in REV before? What kind of prop do you have? Folding or feathering props can malfunction, especially when they haven't been cleaned in a while. You may need to take a trip over the side and visually inspect your prop and check for full range of motion. If it is a fixed prop, less likely to be the problem.

When you have eliminated the cheap and easy fixes, you probably have an issue with your transmission. This is the least likely, and also the more expensive to fix.

[EWOL Props]

If it's a Sail-Drive with many engine hours most probably the problem is at clutch level

[01kiwijohn]

Originally Posted by Southern Ocean

I had the same problem with my Kiwiprop which feathers.
Took a long time but I think I have it sorted now.
In my case the torsion on the spring was to strong. I eased it a significant amount and now engaging and revving in reverse.

Interesting. A year ago I had the same issue with my Kiwiprop. Found 2 problems.
a) The screw h, which bear against thte reverse rollers of the new style blades, were not flush with the surface, causing the blades not to go into reverse fully.
b) The original spring setting, of 3.5 to 4 lbs initial torque, was too high. the new spec, of just 2lbs for first inch of travel has proven to give much better engagement.