Shift Shaft pops out when pressure test is done.

[ChrisSmith290]

Here is a clip of whats going on when I start pumping air into the lower

 

[ChrisSmith290]

Here is a pic of the lower

 

[Bt Doctur]

I`ll admit, its the strangest thing I have seen yet.The only thing I can think of is the blast of air is moving the clutch dog. what happens if you introduce the air gradually?

 

[ChrisSmith290]

It moves with the smallest amount of air. Then its like spring loaded with pressure. I'ts impossible to try to turn the shift shaft clockwise unless the air is let out.

 

[Mercruiser420]

Can you take out the shift shaft and look down the hole with some light and slowly pressurize it and see if you can fingure out whats happening.

 

[cdiamond]

i cant remember ever pressure testing a drive when " in gear "

dont know any reason to do so

heres my WAG

i think what is causing the shift shaft to move

is actually the prop shaft

every drive ive tested - the prop haft will move out when pressure is applied

i think the prop shaft is pulling the shift spool - thereby rotating the shift shaft

my best guess anyhow

 

[JustJason]

I watched the video Is the shaft actually popping up, or just turning?
Does the lower unit shift correctly?

 

[ChrisSmith290]

It's not popping just turning. The reason the drive is in gear when pressure tested is because the entire drive system from yoke assembly to prop shaft should be turning to ensure all seals are not leaking. I've always done it that way for almost 30 years.

 

[ChrisSmith290]

JJ thanks for the reply. Yes the drive shifts perfectly. That's the thing , I was just doing routine winter maintenance. I had no issues with shifting, no water in oil, just worn seal and bad small yoke (grooved) on the yoke assembly. Changed it , piece of cake. No leaks except this weird shift shaft thing. And again the other drive does not do this and they are both right rotation but that shouldn't matter.

 

[ChrisSmith290]

CD you are correct about the prop shaft. When air is injected the prop shaft moves out and thas what is turning the shift shaft. I'm getting closer

 

[ChrisSmith290]

I'm going to post another clip of just the prop shaft

 

[ChrisSmith290]

I tried to keep my phone as steady as possible but you can see the prop shaft pop out. Thanks for checking it out

 

[JustJason]

That prop shaft is moving way to much. Did you remove the bearing carrier from the lower unit?

 

[ChrisSmith290]

Only after I was trying to find the problem. It was doing it before I started tearing it apart. Looked good in there just replaced o ring and oil seal on carrier.

 

[alldodge]

Don't see an end play measurement reading in the manual but that does look like to much. There are shimming procedures

 

[JustJason]

There isn't a spec in the manual but a properly assembled lower will have about 1/8th of an inch of end play in the prop shaft.

A number of things can cause this. If the carrier isn't fully seated, the nut not properly tightened, or a bearing issue in the carrier would all cause this. OP you are going to have to tear things down and have a look. Or take it to somebody more familiar with the drives. If you attempt to run it like that the lower isn't going to last very long.

 

[Bt Doctur]

Agreed, was too much movement. you need to disassemble it to find out why.the shaft moving out that much is pulling the clutch dog and moving the shift spool that is moving the selector and moving the shaft

 

[ChrisSmith290]

Everything looked good to me. I'm posting a video of the prop shaft and the amount of play in it. Keep in mind it's been like this for five years now, just not sure why?

 

[ChrisSmith290]

This is the prop shaft play. Anybody know if this is excessive. There is nothing broken. Pin goes through, nothing seems worn out or broken

 

[Bt Doctur]

what I see in the video is prefectly normal, with the propshaft fully seated in the housing ,the propshaft itself will have about a 1/8th inch movement when fully assembled. If the propshaft still moves more that an 1/8th inch you have to find out why.