Replace or Repair, where to start?

[craig newton]

With an r, mr , or alpha gen one drive when you split the halves of the drive you need to make sure the lower is in fwd and the shift arm in the upper is facing fwd when you out the two halves together.
there is a short splined shift shaft sticking out of the lower, i think you need to turn it clockwise fully and make sure it is in fwd before putting the halves together, if this is good when you slide the drive with remote in fwd u should be good

when you said 'shift arm in the upper is facing forward" do you mean in the top half of the outdrive? I only saw a tube that the shift shaft goes up in. I'll look again. Thank you

 

[Scott06]

when you said 'shift arm in the upper is facing forward" do you mean in the top half of the outdrive? I only saw a tube that the shift shaft goes up in. I'll look again. Thank you

Before anyone yells at me for posting another site i tried to find the parts drawings here on iboats but they come up as no parts available with no drawings ....

Mercruiser Alpha One Parts Drawing

Mercruiser Alpha one upper gearcase parts drawing. Outdrive gear, seal kit.

www.boatparts.ca

number 43 is the intermediate shift shaft which is held in the upper with a cotter pin. If you split the drive when you reassemble the two halves - This need to be facing full forward when ...

http://www.boatparts.ca/mercruiser-alpha-1-gen-2/lower_unit.html

number 30 is the shift shaft it sticks up about and inch just infront of the water pump this needs to be turned clockwise fully when you put the two halves together. That keeps the drive in fwd to mate with the shift shaft in the bell housing - the tube i think you are describing above in the exhaust passage of the bell housing. That shift shaft below the bellhousing should be facing straight forward when the remote is in fwd.

i suspect the two drive halves are out of sync and the lower isn't in fwd hence why you cant move it with the remote. When you shift it only rotates the shift shaft in the lower about 90 degrees counter clockwise from fwd thru neutral to reverse (12 oclock, 10:30, and 9 o’clock respectively when viewed from above the shift shaft.

im going from memory but i think thats right...

 

[craig newton]

Before anyone yells at me for posting another site i tried to find the parts drawings here on iboats but they come up as no parts available with no drawings ....

Mercruiser Alpha One Parts Drawing

Mercruiser Alpha one upper gearcase parts drawing. Outdrive gear, seal kit.

www.boatparts.ca

number 43 is the intermediate shift shaft which is held in the upper with a cotter pin. If you split the drive when you reassemble the two halves - This need to be facing full forward when ...

http://www.boatparts.ca/mercruiser-alpha-1-gen-2/lower_unit.html

number 30 is the shift shaft it sticks up about and inch just infront of the water pump this needs to be turned clockwise fully when you put the two halves together. That keeps the drive in fwd to mate with the shift shaft in the bell housing - the tube i think you are describing above in the exhaust passage of the bell housing. That shift shaft below the bellhousing should be facing straight forward when the remote is in fwd.

i suspect the two drive halves are out of sync and the lower isn't in fwd hence why you cant move it with the remote. When you shift it only rotates the shift shaft in the lower about 90 degrees counter clockwise from fwd thru neutral to reverse (12 oclock, 10:30, and 9 o’clock respectively when viewed from above the shift shaft.

im going from memory but i think thats right...

Thank you Scott06

 

[craig newton]

Look into the upper from the bottom, it's the plastic piece where the copper pipe fits in.

There is what look like the burnt remnants of a piece of plastic in that spot.

 

[poconojoe]

There is what look like the burnt remnants of a piece of plastic in that spot.

I think you are referring to the (plastic) water tube. If you overheat, that tube will likely melt. Get a new one and make sure it mates up when you put the lower half back onto the upper half. If it doesn't line up, the water will not make it up to the engine and you will overheat...again.

As far as flushing goes...
Flush it good from the engine back. You don't want any of those rubber parts from the trashed impeller blocking water flow.

You mentioned antifreeze. I don't know why you added that. I can't think of any reason to do that unless you have a closed cooling system, which you said you do not. It's not a car. It's a completely different animal. I hope it was non-toxic (RV, the red stuff), not automotive antifreeze since it will immediately exit the boat and end up in the water.

As far as your engine goes, what you describe doesn't sound good. All that smoke doesn't sound good.
You'll have to diagnose it to determine how bad it is. I'm no expert on that. I hope the experts will chime in and give you advice.
I would pull the oil dipstick and see and smell if the oil is burnt. Maybe do an oil change and then check compression on all cylinders.
Maybe you caught it in time and didn't score any cylinders or trash any pistons, rings or connecting rods.

If something like that ever happens again, do not restart it, get a tow before you cause more damage.

Keeping my fingers crossed for you.

 

[craig newton]

Thank you Scott06

I think the only way for me to know that it is facing forward is to rotate the shift shaft CW until it stops. I don't see anything that could face forward. Here's a pic showing what I have (bottom of the top half and top of the bottom half)

 

[craig newton]

I think you are referring to the (plastic) water tube. If you overheat, that tube will likely melt. Get a new one and make sure it mates up when you put the lower half back onto the upper half. If it doesn't line up, the water will not make it up to the engine and you will overheat...again.

As far as flushing goes...
Flush it good from the engine back. You don't want any of those rubber parts from the trashed impeller blocking water flow.

You mentioned antifreeze. I don't know why you added that. I can't think of any reason to do that unless you have a closed cooling system, which you said you do not. It's not a car. It's a completely different animal. I hope it was non-toxic (RV, the red stuff), not automotive antifreeze since it will immediately exit the boat and end up in the water.

As far as your engine goes, what you describe doesn't sound good. All that smoke doesn't sound good.
You'll have to diagnose it to determine how bad it is. I'm no expert on that. I hope the experts will chime in and give you advice.
I would pull the oil dipstick and see and smell if the oil is burnt. Maybe do an oil change and then check compression on all cylinders.
Maybe you caught it in time and didn't score any cylinders or trash any pistons, rings or connecting rods.

If something like that ever happens again, do not restart it, get a tow before you cause more damage.

Keeping my fingers crossed for you.

Thank you, keeping mine crossed too. I changed the oil and checked compression on all cylinders without starting the engine. The plugs were old but didn't look too bad. I replaced them anyway. Comp. was 3 at 120 - 4 at 118 and 1 at 119. I back flushed the hell out of it with the lower half of the outdrive off. And installed a new water pump kit including the base. My first attempt at re attaching to the upper I was unable to shift the remote out of forward so I'll be trying that again. I'm hoping the impeller was responsible for most of the smoke. We'll see. Thanks again for your help.

 

[poconojoe]

Thank you, keeping mine crossed too. I changed the oil and checked compression on all cylinders without starting the engine. The plugs were old but didn't look too bad. I replaced them anyway. Comp. was 3 at 120 - 4 at 118 and 1 at 119. I back flushed the hell out of it with the lower half of the outdrive off. And installed a new water pump kit including the base. My first attempt at re attaching to the upper I was unable to shift the remote out of forward so I'll be trying that again. I'm hoping the impeller was responsible for most of the smoke. We'll see. Thanks again for your help.

Sounds like you are on the right path.

From what others have said, your compression test numbers are a bit low. Again, I'm not an expert, but if it were me, I'd just go for it and see how it runs.

At this point I think you are realizing that bad things can go wrong with an overheat condition real quick in a marine I/O engine.

There's another item that can get burnt up during an overheat condition. They are the exhaust shutters and are located inside the exhaust risers on either side of the engine.
They are metal flappers that are encased in rubber. What happens is the rubber burns up and the metal parts fall down into the lower part of the exhaust. I once found part of one all the way down in the lower half of my stern drive. The previous owner must have had an overheat situation.
What they do is prevent water from being forced backwards up through the drive, through the risers and into the cylinders. This can cause hydro-lock, which can break things like connecting rods.
If you're cruising along and suddenly shut down the throttle, water can rush toward your stern and get forced up through the exhaust. The shutters are sort of a check valve to stop the water. So, don't do any quick sudden throttle stops. Make all your stops gradual.

It's probably a good idea to change your thermostat too. A simple economical way to rest easy.

So, keep an eye on your temperature gauge. Know what the normal temperature should be for your engine.

 

[Scott06]

This is the intermediate shift shaft you are looking at the bottom of it in the center of photo 1 . look on top of the cavitation plate this should be facing forward when the controller is in fwd, check its not bent and properly engaging shift mechanism hanging off bottom of bell housing. Make sure the lower stays in fwd by turning the prop ccw to keep it from poping out if gear. If you over heated it you may melt the water tube fittings flappers and rubber connectors in the exhaust system,

 

[nola mike]

I think you are referring to the (plastic) water tube. If you overheat, that tube will likely melt. Get a new one and make sure it mates up when you put the lower half back onto the upper half. .

NO. This is not what I'm talking about, nor what the op is likely looking at. The plastic water tube is a guide only and unrelated to the water pocket cover. The cover is held on with 4 fragile screws. If it's melted, the copper tube won't mate correctly and will suck air. Take a pic looking up into the upper and let us see.

Edit: first pic in post 26 shows what I'm talking about. You can see the 2 holes in the upper on the right side. Shaft goes in one, water tube in the other. You can see the 4 bolts there. I can't zoom enough on my phone, but there's at least a bit of melting there.

 

[poconojoe]

NO. This is not what I'm talking about, nor what the op is likely looking at. The plastic water tube is a guide only and unrelated to the water pocket cover. The cover is held on with 4 fragile screws. If it's melted, the copper tube won't mate correctly and will suck air. Take a pic looking up into the upper and let us see.

Not doubting your knowledge or suggestion.

What I was referring to was...
When I serviced my impeller for the first time (third owner), the plastic water tube was slightly melted.
I wanted to make sure the OP checked that tube since overheating can melt it. Without that tube properly connected, the water will not be able to reach the engine.

Sometimes I wonder what the manufacturer was thinking by making such important parts out of plastic.

Off topic, but...
Another example of this is the stupid plastic through the transom bulkhead fitting for the drive lube reservoir hose. Not knowing it was plastic and doing my first bellows job, I pulled the hose and that plastic transom fitting snapped off. What a nightmare reaching around my 4.3 to access the "E" clip!!!!

 

[nola mike]

Not doubting your knowledge or suggestion.

What I was referring to was...
When I serviced my impeller for the first time (third owner), the plastic water tube was slightly melted.
I wanted to make sure the OP checked that tube since overheating can melt it. Without that tube properly connected, the water will not be able to reach the engine.

No, still not correct. That plastic tube is a guide only. The actual water tube is copper. Plastic tube isn't necessary. But yes, plenty of other plastic to break/melt.

 

[poconojoe]

No, still not correct. That plastic tube is a guide only. The actual water tube is copper. Plastic tube isn't necessary. But yes, plenty of other plastic to break/melt.

Ah, OK. I stand corrected. I guess my memory is not what it used to be.

 

[craig newton]

NO. This is not what I'm talking about, nor what the op is likely looking at. The plastic water tube is a guide only and unrelated to the water pocket cover. The cover is held on with 4 fragile screws. If it's melted, the copper tube won't mate correctly and will suck air. Take a pic looking up into the upper and let us see.

Edit: first pic in post 26 shows what I'm talking about. You can see the 2 holes in the upper on the right side. Shaft goes in one, water tube in the other. You can see the 4 bolts there. I can't zoom enough on my phone, but there's at least a bit of melting there.

nola, I put the copper tube in and it seemed to fit pretty snug. Is the arrow in this pic pointing at the water cover? If so do you think it should be replaced?

 

[craig newton]

sorry I forgot the pic

 

[craig newton]

NO. This is not what I'm talking about, nor what the op is likely looking at. The plastic water tube is a guide only and unrelated to the water pocket cover. The cover is held on with 4 fragile screws. If it's melted, the copper tube won't mate correctly and will suck air. Take a pic looking up into the upper and let us see.

Edit: first pic in post 26 shows what I'm talking about. You can see the 2 holes in the upper on the right side. Shaft goes in one, water tube in the other. You can see the 4 bolts there. I can't zoom enough on my phone, but there's at least a bit of melting there.

 

[nola mike]

Yes, that's it. Parts that I can see look ok, it looked a bit melted in the other pic. Fitting snug is the most important part, and those bolts apparently tend to snap off when you try to remove them. I'd probably give it a shot, recognizing that it might be an issue...

 

[craig newton]

This is the intermediate shift shaft you are looking at the bottom of it in the center of photo 1 . look on top of the cavitation plate this should be facing forward when the controller is in fwd, check its not bent and properly engaging shift mechanism hanging off bottom of bell housing. Make sure the lower stays in fwd by turning the prop ccw to keep it from poping out if gear. If you over heated it you may melt the water tube fittings flappers and rubber connectors in the exhaust system, View attachment 334169

I finally get it! Thank you, will try again

 

[Scott06]

I finally get it! Thank you, will try again

Hopefully Im steering you straight. I had a hell of a time first time putting and outdrive on because it kept popping out of gear, that maybe what is happening here

 

[craig newton]

Hopefully Im steering you straight. I had a hell of a time first time putting and outdrive on because it kept popping out of gear, that maybe what is happening here

It's on! Running and shifting great.