MMI rebuilt install

[JOHN COOKSON]

Marty
As I'm sure you know the packing nut/gland should be the same temp as the water it is in. If the packing is running hot you can burn out the packing and possibly burn the shaft.
You can check the temp with a digital infrared thermometer or or your personal digit thermometer. Careful around moving machinery.
If you can't get a drip rate you like and have the packing gland at the same temp as the surrounding water you will have to repack, realign or re something.

TRUE GRIT

[JOHN COOKSON]

While doing the tests above, I noticed my stuffing box has a slight wobble. No drips, even when running. Never did this before. Very perplexed as I am sure I had the alignment good....even very, very good. What the heck?
Could the engine have shifted somehow?
Could prop cleaning and new zinc affect the balance?
Is the cutlass bearing worn out?
When removing the old A4 the output coupling hung up and suddenly released with a thud. Could that be enough to bend the shaft? Say it ain't so.
Marty

Check to see if the motor mounts are tight.

TRUE GRIT

[Marty Levenson]

stuffing box

Thanks John: I will be checking that for sure.

I am guessing that the amount of growth on the prop was extreme enough to affect its balance. So, while I aligned the engine to the shaft pre prop cleaning, now it is out of alignment. I will unbolt the output coupler and measure asap.

-Marty

[Marty Levenson]

exhaust question

Shifting to another topic, my old cast iron exhaust is showing signs of rusting out. Pulled it and the riser off a couple days ago, and the riser broke as I tried to unscrew it from the muffler after removal.

So, bought a Vetus plastic muffler locally, and ran around to four different plumbing stores today to get all the 1.25" black iron parts I need to replicate the original riser. Photos attached below. Plan to cut down the 2" pipe so it has no threads for a better attachment to a clamped exhaust hose between that and the muffler.

Question 1 - does that all look okay? The original muffler had a built in water injection port, so had to add a piece to introduce the hot water. Photo shows two different options: one straight and one as part of the 90 degree elbow. If there is room I plan to use the straight version as bringing the water hose out to that barb is going to be tricky.

Question 2 - the muffler has 2" connectors. So, I bought a coupler to go from 1.25" to 2" just past the water injection. Will that increase in diameter cause any problems? The hose it connects to (to the tail pipe) was and is 1 5/8" ID.

[Marty Levenson]

split coupling question

Looks like I will be pulling my shaft....out of the boat.

Considering getting the MMI split coupling, but not sure if I need it. Consensus on the forum is that it is great, so not questioning that. Is it that hard to remove the old coupling after 40+ years? Is it hard to attach the coupling again?

I believe I will be getting my shaft straightened, not replaced, so don't want to cut it if possible. tips on removal? Boat will be on the hard.

Thanks!
Marty

[Van_Isle]

I spent 3 days with a drilled plate, 2 or 3 wrench sockets, a mallet, a heat gun and various penetrating oils such as kroil and deep creep to get my old shaft coupling off. Couple things:

1) I had very little room between the engine and the coupling to work with. I disassembled the stuffing box to give me more room and cut off the old hose. But you have to be careful in rotating the whole thing not to chew-up your stern tube.
2) stacked a couple ratchet wrench sockets to fit inside the old coupling, alongside the key. I used some butyl tape squished between the sockets to hold them together while inserting. Plate overtop and bolts through the plate and the coupling with nuts. Couple box wrenches to tighten ... little 'tap, tap, tap' ... little heat .... soak with kroil overnight ... repeat.
3) Do not use the tailshaft flange instead of a 2nd plate to do this as you will most likely break it. I know I bent the crap out of the plate I had!
4) There was no way the key was coming out of the prop shaft and no way to get a drive pin into the slot (due to angle). So the sockets were driving slightly off-center on the end of the shaft. But it worked.
5) Kroil is great, and available through 4thGenTactical in Nanaimo (http://www.4gt.ca/). Do NOT get any of this or other oils such as Deep Creep on your trany seals!
5) It probably would have been easier to cut off the old shaft coupling ... but I wasn't too keen to start using the grinder next to the fuel tank. However, you would cut it at the key.

I used a Moyer split coupling. I don't think there are too many other options kicking around out there. Had it fitted and faced at a local machine shop and the guy cleaned up the prop and checked the shaft for trueness at the same time. I know the machinist said he makes a lot of (typically non-split) couplings but couldn't touch the price Moyer charges. His work on the shaft cost about $130. At the same time I replaced the cutless bearing and installed a PSS dripless stuffing box. I had the guy that did the shaft install the cutless as I didn't have the tool. And I did have a mechanic come and install the shaft and dripless seal and do a preliminary alignment. He came back and did an alignment check once the boat was back in the water. It had changed substantially. That was about $300.

[Marty Levenson]

coupling install questions

Thanks for the info on your removal. Mine was a different story: had to cut it after a LOT of time spent. Seems my cutless bearing was messed up: couldn't slide my shaft back at all. Once cut I used a slide hammer attached where the prop screws on to slowly force it out. Next is new shaft, new coupling, new cutlass bearing, new hose and clamps, clean up the stuffing box. At least I can restuff the stuffing box on the bench!

I'm a little unsure about when the key goes in the coupling end of the shaft. I don't have the split coupling ( MM was out of them!) After the shaft is installed, of course, but before starting to attach the coupling?

Do I screw the new coupling onto the transmission output coupling and then start tapping the prop end of the shaft to get the shaft into the coupling? Worried about hurting the transmission.

Any advice on this part of the process greatly appreciated!

Marty

[Marty Levenson]

further thought

Would it be a good idea to put a piece of soft wood (pine?) between the output coupling and the shaft coupling when I am tapping the shaft into its coupling tomorrow?

Thanks,
Marty

[hanleyclifford]

Marty - The reason you had trouble getting the shaft out of the coupling has nothing to do with a bad cutless and everything to do with the rusted and seized shaft coupling. It is a mega bummer that you have to go back together with one of those solid couplings. Could you not wait or try another source? Maybe Buck Algonquin? If you must use the solid coupling make sure it is without flaws or burrs inside, likewise the shaft. Even the smallest nick will make you pay later when you next remove it. The shaft should be slid in carefully and the key laid in the keyway noting where the taper of the key is aft. The biggest danger is that the key will be too far aft in the keyway and cause the key to rise in the keyway ever so slightly causing the coupling to bind at the aft end when slid on. Don't let it happen. Keep the key slightly forward in the shaft and slip the coupling on slowly. Oil both pieces with light machine oil first. Cleanliness is important here. Once the coupling is on and the depression for the lock screw is centered check where the front of the key is to be sure it will not contact the gearbox shaft nut upon assembly.

[Marty Levenson]

shaft -key - coupling

Thanks Hanley - greatly appreciate your thoughts.

" It is a mega bummer that you have to go back together with one of those solid couplings. Could you not wait or try another source? Maybe Buck Algonquin?"

I agree! I could not find another source for a split coupling suitable for A4 with 1" shaft. The coupling I bought is Buck Algonquin.

" If you must use the solid coupling make sure it is without flaws or burrs inside, likewise the shaft. Even the smallest nick will make you pay later when you next remove it."

Very reputable machine shop here did fit and face on the new coupling: it looks good.

"The shaft should be slid in carefully and the key laid in the keyway noting where the taper of the key is aft. The biggest danger is that the key will be too far aft in the keyway and cause the key to rise in the keyway ever so slightly causing the coupling to bind at the aft end when slid on. Don't let it happen. Keep the key slightly forward in the shaft and slip the coupling on slowly. Oil both pieces with light machine oil first. Cleanliness is important here. Once the coupling is on and the depression for the lock screw is centered check where the front of the key is to be sure it will not contact the gearbox shaft nut upon assembly."

Really valuable info: please let me know if I have this right: So, the shaft goes part way in, then the key gets inserted, then the shaft goes the rest of the way in, then the key tapped back if necessary?

Whole operation makes me nervous!

[hanleyclifford]

First get the shaft into the boat past the stuffing box. Then lay the key into the shaft with some of the key extending forward of the shaft. Then start the shaft coupling onto the shaft making sure the key does not move aft. When the coupling has reached it's final position on the shaft (depression for lock screw visible and centered in the hole), install the lock screw hand tight. Tap the forward end of the key lightly; it should move aft slightly until it gets to be out of reach of the gearbox shaft nut when you lastly bring the assembly into contact with the gear box output coupling. Use minimal force tapping the key aft. If it won't go aft easily it is too long and must be shortened. When adjusting a key in a shaft it is a good practice to use a drift or punch with a light ball peen. Try to drive in the center of the key end, never striking the edges.

[Marty Levenson]

key and shaft

Thanks for the further explanation....really useful.

Marty

[Marty Levenson]

progress

Yesterday we finally made some progress. Spent about two hours trying to bang in the final 1" of the new cutlass bearing (soft wood and a 3 lb mallet). I got worn out half way. Borrowed a 3/4" threaded rod with extra big threads (sorry forgot what that is called: anyone know?) and sturdy washers. Pressed it in in two minutes.

New stuffing box hose and clamps: restuffed box with Gore GTU.

Had trouble getting the key snugly into its slot in the shaft in the "engine room", but filed the width down very slightly and it went smoothly from there (thanks Hanley). New coupling slid onto the shaft with minimum tapping on the other end of the shaft. Tapped the key aft with a drift and done.

Same issue with the key at the prop end, but prop now well installed after minimal messing around.

Alignment today. Noticed the shaft coupling meets the output coupling about 1/8" lower down than before.

Thanks,
Marty

[Marty Levenson]

Alignment question

I spent part of today working on the alignment on the hard. Things seem quite different with the new shaft, but wondering if it is also due to being out of the water. I got the two coupling perfectly aligned, but off center by about 1/8"!

I am worried that running the boat this way just about half a mile max to our dock. Will the hurt the cutless bearing, transmission, or stuffing box somehow. We splash Monday, so I could go work on it again Sunday, but wondering if it is a waste of effort as it will need to be redone once we are in the water.

Advice appreciated!

[hanleyclifford]

Not sure what you mean by "off center". If that means with respect to the shaft log there is no problem but if you had to force the coupling over to meet the engine output coupling that could be a problem. What really matters is how the shaft lies in the cutlass. Dead center in the shaft log does not always mean "correct" in relation to the cutlass.