Mercruiser Alpha 1 clicking/ratcheting in reverse

Hey guys, working on my dad's boat again, getting it ready for river trips. We've had some stalling issues while shifting between forward, neutral and reverse. It was the shift interrupt switch being held too long. I just changed the engine and gear oil along with a new impeller kit. I adjusted the shift cables and warmed it up and it did not stall shifting between the gears. Big relief. This was out of the water though, with the earmuffs on. It makes a clicking/ratcheting sound in reverse though. Only reverse. It goes into gear normal then 2-3 seconds later it starts clicking about 2-3 times per second at idle. Is this a result of not lining up the lower with the upper when i did the impeller? i don't think so because it is perfect in forward gear. Shift cable slightly out of adjustment? Or just a result of no water acting as resistance on the prop and it's completely normal? Thanks

Boat is a 1992 Cobalt 21ft Mercruiser 5.7L/Alpha 1 stored with outdrive down. Shift cable is about a year and a half old and i just replaced the bellows

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

the shift cable is either misadjusted or more likely needs to be replaced

adjusting the shift interrupt switch doesn't do much good with the boat out of the water, there needs to be a load on the prop when shifting to properly engage the shift interrupt switch

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

It sure sounds like a lower cable problem, but if it failed that soon it's probably getting water in it. If its bellows is OK, it would be coming through the shift shaft seal.

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

wrench 3 said:

It sure sounds like a lower cable problem, but if it failed that soon it's probably getting water in it.

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or it was routed incorrectly

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

dubs283 said:

or it was routed incorrectly

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Good point. That's why I attach a fish wire to them before I pull them out. But that wouldn't help if it's routed wrong in the first place.

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

wrench 3 said:

But that wouldn't help if it's routed wrong in the first place.

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exactly

you wouldn't believe how many factory installed cables i replace are routed incorrectly

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

If you find that adjusting the cable doesn't help much, or when it does you find you can barely hit forward, your problem may be a broken clutch dog pin... see #51 in the diagram below, then my broken pin next to it. Mine was from my Mariner outboard, but the Alpha's are similar. Mine acted the same way as yours, 'part-time' reverse at best--

-- the clutch dog is spring loaded towards the forward gear, so even with the pin busted it'll go into forward no problem. But neutral and reverse is a different story, because pressure on the pin is what moves the dog, and when it's broke, it can't move the dog as far as it's supposed to...

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

Frantically Relaxing said:

the clutch dog is spring loaded towards the forward gear, so even with the pin busted it'll go into forward no problem.

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no

the clutch dog is not spring loaded any direction, it merely slides on the propshaft to engage either the forward or reverse gear, springs have nothing to do with it

my guess is the reason yours worked in fwd gear but not rev is due in part to the rotation of the gears themselves and the ramped teeth on the fwd end of the dog

the reverse teeth are lugs and will not engage as easily

alpha clutch dogs have ramped teeth on both ends and there would probably be no rhyme or reason to the shifting if the pin you refer to was broken

to op: focus on the shift cable adjustment or possible misrouting/failure first - 9 times out of ten that is where the shift issue you have lies

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

Did some research, the Alpha's are different than my outboard lower, the main difference is the dog is moved with a "shift spool" in the Alpha's. However, the gen 1 Alpha's do have a compression spring, but the gen 2's do not. But common to all is the dog pin, and if it's broke in half, the results will be the same.

Re: Mercruiser Alpha 1 clicking/ratcheting in reverse

The compression spring in the alphas only holds the shift spool in place on the clutch shaft and does not preload the clutch shaft. A broken pin would just make everything sloppy. But I've never seen one brake in an out drive.