Alpha 1 Shift Problem

[poliz296]

Hi, I have a 1991 5.7l Mercruiser with a alpha 1 drive. I found water in the drive and pressure tested it to find that the short yoke seal was bad I replaced the seal and the drive holds pressure now. The problem is that when the boat is out of the water I can shift it into both forward and reverse gears. When in the water it will shift into gear but will not come out of gear, especially reverse gear, until you shut it down to shift it out of gear. I have checked all of the shift cables and adjusted the cables properly. I have a hunch that it could be that the shift-interrupter switch is either bad, or out of adjustment. The switch does work (when you hold it in the engine dies). Could it be one of the shift shafts? The Shift interrupter switch? Something else?

 

[Laddies]

Re: Alpha 1 Shift Problem

The shift interrupter switch is not working or could be disconnected at the coil or the shift interrupter rocker it stuck

 

[KRS]

Re: Alpha 1 Shift Problem

Although you can manually activate the interruptor switch, the "rocker" (as laddiesservice mentioned) may not be "rocking" properly to engage the switch fully. Check that.

 

[kwoolard]

Re: Alpha 1 Shift Problem

I have the same problem, no matter how much I tweak the cable adjustment it still will not shift out of gear. I know my interruptor works because it will kill the engine when I depress the switch but I don't think the actuator is working properly. Is there anywhere to purchase an aftermarket shift interupter switch and accuator for a 1974 mercruiser?

 

[Don S]

Re: Alpha 1 Shift Problem

Assuming you are talking about the "short yoke seal" as being on the input shaft yoke where the ujoints are, if so, then you need a new bellows also. There shouldn't have been water in the bellows to begin with. All that will happen is the new yoke gets rusty and eats up another seal.<br />If your in salt water, you need a new set of ujoints and gimbal bearing also.

 

[intoodeep]

Re: Alpha 1 Shift Problem

Make shure lower cable routing is correct.<br />interuptor acts on cable housing movement not inner cable

 

[DHPMARINE]

Re: Alpha 1 Shift Problem

No one seems to understand that the shift interrupter switch is made to activate when there is a problem,to help save the gears.Normally when you shift,the switch won't even twitch.<br /><br />Generally,turn your idle speed down,and shifting is a world better.<br /><br />DHP

 

[Don S]

Re: Alpha 1 Shift Problem

Always Something<br />Is your drive an Alpha I, or an Alpha I Gen II. 1991 was the first year of the GenII drives. If your boat is a 91, you could very well have a 90 engine and drive installed.

 

[poliz296]

Re: Alpha 1 Shift Problem

It is an alpha 1 gen 1 drive 1990 model engine and drive, both bellows (exhaust,u-joint) were replaced. the short shaft I was speaking of is the input shaft yoke. The U-joints and gimbal bearing are new also. The idle is set to 550rpm. I am not sure of exactly what you are talking about the lower shift cable being routed properly, perhaps you could explain how it should be routed.

 

[Don S]

Re: Alpha 1 Shift Problem

I doubt the routing of the cable is your problem. If the cable is routed wrong, it can bind and cause the engine to die when trying to shift. Your problem is the shift interrupt system will not activate.<br />My guess is your cables are so far out of adjustment that the switch is not activated, but you can still get to both fwd and rev.<br />What you need to do is read the instructions in the manual (See link to section 2 below) and adjust everything properly. Then it will work.<br /><br /> Section 2 of Merc manual #6

 

[intoodeep]

Re: Alpha 1 Shift Problem

Shift cable needs to go inside bell housing mount on starboard side {r.h}and up between manifold and elbow . No wire ties, cable sheeth has to move. Stutter is there to help sprial cut lower gears unload during a shift. Cable adj is verry important! Get a book and do not skip anny steps,<br />there are three adj.pointsthese can be kind of a bit**. Try backing up twins in a 30'+ when they will not come out of gear or stall. I know , it sucks. resist desire to tie remote cable to anything to make it look pretty. Let it hang

 

[qystan]

Re: Alpha 1 Shift Problem

Check the lower shift lever on the drive is properly seated in the upper shift lever shoe. <br /><br />Try shifting while on water (to have load on the prop) and observe the interrupter mechanism, you should see the lever that actuate the switch move when shifting out of gear.<br /><br />If it does move, possibility is that the switch lever arm needs adjustment. With everything in neutral position, the switch must actuate when a 1/8 inch drill is inserted between the switch roller and the cam, adjust by bending arm.<br /><br />If it does not move when shifting out of gear, inspect the lower shift cable sheath for damage. Also check if the input cable travel is ok and the sheath for breaks/corrosion etc. A bad sheath creates stiff movement and/or lost motion.