Transmission Woes in Vintage Mercruiser

[Jamespio]

Running a new-to-me '66 Mercruiser IC with EZ-shift. I had the sterndrive off in order to evaluate its condition before I was willing to drive it. But I did not crack open the gear box. I also did not attempt any adjustments to the shift linkages when I reassembled it. Although I'm mechanically competent, I have no boat repair experience.

Evenything I fix on this boat reveals another repair to be done. About what I'd expect from a nearly 60-year-old boat. Current issue getting my attention is the transmission. When I shift into forward gear, it's a pretty long throw on the shifter, from idle at 12 high, it doesn't grab forward until I get almost to the 9 o'clock position. But then it shifts into gear pretty smoothly. I can live with that, if I have to.

When I shift to reverse it's a much shorter throw of the shifter, and then a much more pronounced "clunk" as it goes into gear. The worst problem though, is coming OUT of reverse. When I move the shifter to 12 o'clock from forward, I go into idle. When I'm shifting from reverse, at the 12 position the shifter hits a hard spot, I have to push it just a bit harder to make it move th elast inch to find idle, and then it "clunks" again not quite as hard as when it went into gear.

So the mai problem/symptom is with how hard it is going in and out of reverse, but the seconday probalem is that I'd like forward and reverse to be somehwat symmetrical in terms of how far I have to swing the shifter/throttle.

Hoping someone has ideas on what may cause this, and how to diagnose and/or repair. Thanks in advance.

And here she is in her current state. Much work ongoing.

 

[dubs283]

Sweet boat

Not too familiar with the EZ shift mcm drives. I only worked on one and it was painted a metallic light green, same with the Renault engine coupled to it. My first observation was how it resembled an alpha drive but was 80% the size. Everything worked fine and it was a basic winterize I performed so no in depth troubleshooting required.

Please post some pictures of the drive/transom assy, engine and any serial numbers if applicable.

My first guess is the lower shift cable is out of adjustment or likely needs replaced

 

[Jamespio]

Sweet boat

Not too familiar with the EZ shift mcm drives. I only worked on one and it was painted a metallic light green, same with the Renault engine coupled to it. My first observation was how it resembled an alpha drive but was 80% the size. Everything worked fine and it was a basic winterize I performed so no in depth troubleshooting required.

Please post some pictures of the drive/transom assy, engine and any serial numbers if applicable.

My first guess is the lower shift cable is out of adjustment or likely needs replaced

This appears to have a layer of light green under multiple layers of low quality white paint. The engine is a Chevy 230 I/L 6 rated at 150hp.

 

[Scott Danforth]

you know that big old hole should not be in the front of your drive, right. that is freeze damage

also, your shift cables are woefully out of adjustment

 

[achris]

Anybody notice this?



Personally, I think this drive has 'gone to god'...

 

[Jamespio]

Anybody notice this?

View attachment 364789

Personally, I think this drive has 'gone to god'...

That drive has powered me up and down Saratoga Passage half a dozen times. Do you know what's under that damaged cover? The metal body of the upper gear box.

Not everyone is into vintage, especially those who see damage and immediately think "time to throw it away." My approach to that damage, and to the massive hole in the lower unit was different from that. I started with "does the visible damage actually effect operation?" I then moved on to "will the damage lead to additional failure if left alone?" Then "what if fixed?"
In this case, the damage was solely to a portion of the outer aluminum shell, leaving the gear box underneath untouched. In the pic above, one might notice the lack of oil draining through that crack, despite the fact the gear box is literally full of gear oil. That massive crack that makes you think the drive is dead, was entirely cosmetic.

 

[Jamespio]

you know that big old hole should not be in the front of your drive, right. that is freeze damage

also, your shift cables are woefully out of adjustment

The "big old hole" has been fixed, and yes I reached the same conclusion you did.

Was hoping someone might be able to tell me more than "shift cables out of adjustment." Maybe point to some resources on proper adjustment, tell me where the "problem" is likely to be located (at the shifter lever, inside the transom, inside the sterndrive?).
The photos I just shared were taken early in the repair process. Since they were taken, the holes are fixed, the drive is reassembled, the straight-6 engine runs (still a bit rough, but I replaced most of the ignition components), one tilt cylinder was rebuilt (by me) the other replaced, new blower installed, and much more.

Which leads to my question about the transmission (since the holes in the drive are now fixed).

 

[Scott Danforth]

I would buy new cables and follow the manual on adjustment.

cables stretch slightly, however mostly the inner sleeve wears and the throw is not the same. being that your boat is 60 years old, you should be moving to the 5th set of cables by now as they last about 15 years.

 

[Scott06]

The "big old hole" has been fixed, and yes I reached the same conclusion you did.

Was hoping someone might be able to tell me more than "shift cables out of adjustment." Maybe point to some resources on proper adjustment, tell me where the "problem" is likely to be located (at the shifter lever, inside the transom, inside the sterndrive?).
The photos I just shared were taken early in the repair process. Since they were taken, the holes are fixed, the drive is reassembled, the straight-6 engine runs (still a bit rough, but I replaced most of the ignition components), one tilt cylinder was rebuilt (by me) the other replaced, new blower installed, and much more.

Which leads to my question about the transmission (since the holes in the drive are now fixed).

Do you have a factory manual for that drive ? Unfortunately most of us don't have hands on experience with that drive due to age and limited amount built vs later drives like MC-1 and alphas.

So would recommend finding the factory manual and adjusting cables to spec.

Merc only made this drive 64-66 so parts availability may be an issue.
It was for me 25 years ago - My grandfather had the same 150 hp and drive in his '66 Penn Yann. Drive was originally white over green dichromate primer if I recall. We had the same freeze issue in lower front of drive just epoxied over it. Biggest issue we had is the tilt never really worked from new and was never able to be fixed despite a lot of effort

There is no transmission on it- in the lower unit when you shift it just locks forward or reverse gear to prop shaft. In addition to the cable adjustment or replacement any shift mechanisms in the bellhousing need to be moving feely and smoothly. Would take the lower shift cable off the shift plate and move it by hand. Do the same with the helm this should isolate where the hang up is. Willing to bet you will end up replacing all parts and cable involved with shifting, but again start with factory manual if you can get your hands on it.

 

[Jamespio]

Do you have a factory manual for that drive ? Unfortunately most of us don't have hands on experience with that drive due to age and limited amount built vs later drives like MC-1 and alphas.

So would recommend finding the factory manual and adjusting cables to spec.

Merc only made this drive 64-66 so parts availability may be an issue.
It was for me 25 years ago - My grandfather had the same 150 hp and drive in his '66 Penn Yann. Drive was originally white over green dichromate primer if I recall. We had the same freeze issue in lower front of drive just epoxied over it. Biggest issue we had is the tilt never really worked from new and was never able to be fixed despite a lot of effort

There is no transmission on it- in the lower unit when you shift it just locks forward or reverse gear to prop shaft. In addition to the cable adjustment or replacement any shift mechanisms in the bellhousing need to be moving feely and smoothly. Would take the lower shift cable off the shift plate and move it by hand. Do the same with the helm this should isolate where the hang up is. Willing to bet you will end up replacing all parts and cable involved with shifting, but again start with factory manual if you can get your hands on it.

I'm fighting with the tilt, not surprisingly. PO made modifications, adding a rigged up fluid reservoir that tends to leak into the bilge. I cannot tell if there was, originally, any reservoir outside the pump at all. Don't suppose you happen to remember? There's a brass tube off the pump for filling, and that is where PO added a line to a reservoir. Not sure if that line is not merely supposed to be capped after filling the pump. Tilt works OK when reservoir is full, but as it leaks that becomes a pretty constant problem.

 

[Scott06]

I'm fighting with the tilt, not surprisingly. PO made modifications, adding a rigged up fluid reservoir that tends to leak into the bilge. I cannot tell if there was, originally, any reservoir outside the pump at all. Don't suppose you happen to remember? There's a brass tube off the pump for filling, and that is where PO added a line to a reservoir. Not sure if that line is not merely supposed to be capped after filling the pump. Tilt works OK when reservoir is full, but as it leaks that becomes a pretty constant problem.

Some one cobbled this already.

Originally grandpas boat came with a white tilt pump and reservoir (combined not separate) that took ATF. Had a very small reservoir that was a PITA to fill.

A machinist buddy of his rigged up a pipe attached to it to enlarge the reservoir. Didn't fix the issues we regularly had to top off ... Again from new this system never worked. He replaced the trim rams to no avail, just learned to live with it and tie the drive up to the transom when you needed it to stay up...

Later on local merc mechanic replaced white pump with a black metal one off I think and early tilt only MC-1, again never fixed , just had to remember to keep hitting up button when in shallow water.

While I have fond memories of this boat and catching a lot of lake trout with my grandparents, you are peeing into a fan trying to keep this going. I know not what you want to hear but the fact that Merc only made it for 3 years then introduced the longer running MC-1 means they learned something and made a significant redesign. Unfortunately due to age, lack of parts, and all the guys who worked on them new are retired you will have a tough time getting info.