68 Mercruiser 120 (MC1) lower unit installation

[Fisch]

First off, great forum ... I've read some of the information on various subjects and the knowledge base seems very strong.

Which, leads me to register and ask this:

I've just replaced the impeller, related gaskets, tube guide, etc.

Anyhoo ... I dropped the LU with everything in forward, have everything back together and 'in position with the LU and upper both in forward still ... water tube is lined up and started in, shifter is lined up and in position and seated ... but I can only get the unit to with about 3/4" of being installed.

Now, I've tried to put a bit of wiggle on it while my wife slowly turns the prop CCW, assuming that the drive shaft splines were simply not aligned ... to no avail.

I placed a small wooden bench below my skeg, and actually rested my body weight on the upper portion of the unit, while slowly turning the prop CCW and can feel a very gentle lapping while the pressure is applied ... I assume this is the splines on the drive shaft lightly hitting each other disengaged.

Lastly, I'll mention that this is the old style Merc 1 with the O-ring on the top of the drive shaft, which of course is also new ...

I'm assuming perhaps that I'm hanging up where the O-ring is meeting the seal in the upper?

Is it necessary to apply any sort of significant force to get past the "hump" so to speak with this O-ring?

Any tips, ideas, suggestions? It would really pain me to get this far along in a job and have to admit defeat and take it to the shop. Haha.

Thanks in advance for any and all input.

-Fisch

 

[Bifflefan]

Re: 68 Mercruiser 120 (MC1) lower unit installation

Recheck the shifter in the lower and the mating piece in the upper.
I think one of them is not lined up just right.
If you have turned the prop just a bit the wrong direction it will move the splined part of the shifter in the lower and not let it fall into place.

And welcome aboard.

 

[Eric 3.7LX Alpha 1]

Re: 68 Mercruiser 120 (MC1) lower unit installation

Sounds like your doing it right, it should go,
Eric

 

[Fisch]

Re: 68 Mercruiser 120 (MC1) lower unit installation

Well ... low and behold after heading back to the garage with a clear head today, I came to find that the tube guide that the dealer gave me was slightly different than the old one, which had melted a little when the pump failed, preventing me from spotting this right away.

Anyhoo ... the one he gave me had a small lip on one end, essentially making the I.D. smaller ... so it fit on the tube, but stopped at this lip of course, and fed into the water pump housing but also stopped at the normal place a guide tube would stop.

Deal being, the stop at the end of the tube was preventing the tube from setting slightly lower into the water pump housing, which of course made for my 3/4" inch issue.

Long story short, a bad part ... which I had no good original to compare to, but was able to modify by trimming about 1/16" inch off the end (to get rid of the lipped portion) ... managed a nice, clean cut ... and put a tiny skin of rtv on it just to help out with seating (the housing will be replaced with the next impeller anyway) ...

Fired her up tonight, and everything is seemingly good. No hot engine ... forward and reverse are working as intended ...

Now this question though ...

This is the first time I've done this work ... there is a small hole on the side of the L.U. above the water intakes ... when the engine is running, water is now coming from this hole ... also, water is coming from the hole that the shifter arm sits in ... shifter is seated snug, and working fine, but don't recall water in either of these places before ... is it normal from either?

Water was of course, exiting at the prop as well ... and more so when the engine was revved.

Normal discharge spots? I can accept that maybe something was cleaned or cleared by moving parts around, cleaning, etc ... just want to be safe before launching.

Thanks again for all input!