Starts and runs. Stalls when I try to shift into gear....

[malangon]

Mercruiser MCM 3.0L inboard with an Alpha 1 Gen 2 stern drive. I just took apart the sterndrive because apparently I'm an idiot and thought I should/could do it. Replaced some orings, seals, and the water impeller.

When I start the engine, it runs fine. Maybe feels a bit rough, but starts without a problem and runs without any issues in neutral. I have 2 questions:

1) When it's in neutral, I noticed that the propeller is spinning. Not very fast, but spinning nonetheless. Is this normal? I can't remember.

2) The bigger problem is even though the engine is running fine in neutral, when I try to shift it into gear, it immediately stalls. Every time.

Obviously have a problem if I can't get this into gear without the stalling. Any suggestions? I'm wondering if I screwed up putting this thing back together somehow.

 

[muc]

1. Some do, most don’t.
2. Watch the shift interrupt switch when shifting. It shouldn’t move when Boat is out of the water.

Yup, I’m guessing you messed something up. But that’s how most of us learn.

 

[Rick Stephens]

But that’s how most of us learn.

Yup

 

[Lewis1111]

Do some searching on the shift interrupt switch. Most likely it is engaging and killing the engine as you are shifting.

 

[harringtondav]

My guess is the propeller shaft hsg. shift spool, yoke and shift shaft are misaligned somewhere. The yoke must face to the left/port side of the gear hsg. before installing the prop shaft assy. The shift shaft splines should be set so the yoke swings slightly (+- 10 o'clock) forward with the top of the shaft at 12:00 o'clock - full forward. With the top of the shift shaft at 9:00 o'clock the yoke should be at around 8:00 o'clock. You have to hold your mouth right, and tilt the end of the prop shaft left to engage the yoke in the shift spool groove. This is tricky, but you'll know when it's engaged because the prop shaft assy won't pull straight out. It must be engaged. My guess is it is not, and the shift yoke dead ends against something. The shift cut out switch reacts to push-pull force between the shift cable core and OD. If it dead heads, it will hold the cut out switch closed - and kill the engine.

 

[nola mike]

Did it work correctly before you took it apart? Does it stall going into forward and reverse? If it worked before, I can think of a couple of reasons to that it would trip now. I'm wondering if you're actually in neutral. If you give it throttle in neutral, does the prop speed increase? It shouldn't, even if it spins a bit in neutral at idle. The spinning is just due to friction on the prop shaft internally. Also, with the boat off in neutral, you should be able to spin the prop in either direction easily.

 

[malangon]

I spoke to one of the mechanics at my local shop and he immediately suggested a bad shift cable.

I found the shift interrupt switch and disconnected one of the wires coming from it. That immediately solved the problem.

So, now I am facing a new set of questions:

1) This is a short term fix because it will supposedly damage the engine. I assume it is a bad cable and needs to be replaced?

2) I noticed that at neutral, the engine will sometimes run fine, but often stalls out. Can I fix this by adjusting idle? If so, how?

 

[Bt Doctur]

1) wont damage the engine but you will have difficulty getting out of gear unles you shut the motor off first.
2) how low is the idle now

 

[malangon]

Not sure how I can describe how low it is. I have had it idling for a few mins at idle but nine times out of ten it stalls out. Seems "low" and I was thinking as a temp measure just so I can get out on the water this weekend, I could adjust it slightly and deal with it.

This sounds terrible, but I just want to Macguyver it for the weekend to take my kids fishing on a lake. Then I'll deliver it to my marine shop who will end up telling me I need to repair 927 things on it...

 

[nola mike]

Sure, try to adjust the idle. Check the timing and point Gap/dwell if you still have them, both affect the idle.

 

[malangon]

nola Mike, with the boat off and the shifter in neutral, the the prop does NOT turn freely. It will turn one way with a heavy click as I turned it. It will NOT turn the other way.

I assume then that when I put the stern drive back on, I screwed it up and it's actually not lined up to be in neutral?

 

[malangon]

Ok, I took the stern drive off and the shift lever (not sure I'm using the right term here) on the stern drive was pushed to the side and not in the groove for the shift lever on the boat.

It was a major ***** to finally get this thing back on and lined up, but it's on now and lined up.

Now the problem I have is when I shift into neutral, I still do not get a free turning prop. I know the lever is lined up and in the groove, but the prop clicks when I turn it one way and won't turn the other way.

No idea what this means now. Too late to start this thing up since it sounds like a jet engine.

Any ideas before I blow myself up in the morning?

 

[harringtondav]

If it shifted OK before you disassembled it, I go back to my comments above. I suspect the prop. shaft hsg. shift lever is out of time by one spline, or the spool yoke is out of position. Pull the O/D back off. Set the shift lever dead forward and hold it. The prop should ratchet CW (forward), but lock CCW. Turn the shift lever as far left as it will go and hold it. Now the prop should ratchet CCW (reverse) but lock CW. With the lever just left of forward you should be in neutral with a free spinning prop either direction. If you don't get this, time to tear back into the prop shaft hsg and straighten things out. You may get luck by removing the shift shaft seal holder, lift the shaft from the yoke, and reposition it by one spline to achieve the above.

 

[nola mike]

At least you're going to get good at removing the drive! Don't worry, you can still get out this weekend. As harringtondav said, you probably are if by a spline. First, remove the drive. With the shift lever straight ahead, the prop should lock CCW. If so, great. If not, you'll need to split the drive. The small splined shift lever in the lower should be turned cw. At this point, the prop should lock CCW. Hold it there with a bungee or something. Now put the upper back with the shift lever pointed straight ahead. When you're done, prop should lock CCW. The lever should turn 45'or so CCW, at which point the prop should lock cw (which is reverse). Somewhere in the middle is neutral. Also check to make sure you didn't distort the upper shift shaft and shoe on the bell housing when you put it on last time. Good luck

 

[malangon]

Thank you all for the advice. On another board I posted the same issue and I got about 19 replies of "rebuild the carb". Seems to be a standard response!

I found that my shift shaft was off by a spline. I pulled it, pushed it back in and it magically rotated in the right direction. When I remounted the sterndrive, I get the free spinning in neutral.

I also noticed that shifting was easier (duh!) and I could get the engine to idle in neutral without too much trouble. Still not perfect but I'll take it.

Tomorrow will be the trial run on the lake. Going to a small lake because it'll be easier to swim to shore...

Thanks again and Happy 4th! Thanks harringtondav and nola mike!