Lower unit and or motor & lower unit swap

[Spanky-05]

Apologies if I posted to the wrong thread. So I have a 1990 bayliner Capri with the 3litre inline 4 mercruiser alpha one. Atleast one seal is done, bad noise in reverse (only can hear it out of the water) and grinds going in gear (tried to adjust cables no luck). I acquired a boat from a friend with a interior that's done. But it has the 4.3l V6 mercruiser and the lower unit was rebuilt before it was parked for years. What's the chances I could direct swap the motor and or atleast the lower unit. It's around the same year. Any input is appreciated

 

[achris]

Ratio in the drive for the 3 litre is 1.98:1 and the ratio for the V6 is 1.65:1. You may not get a prop small enough to run on the 3 litre with the 1.65 drive.

Those drives use a dog clutch, they do grind when engaging. If you're 'easing' it into gear, stop doing that. You drop it into gear, single quick shift.

The noise you are hearing on reverse may be normal. With no load on the prop it may be just bumping on the backside of the dog clutch...

Chris.

 

[Spanky-05]

Ratio in the drive for the 3 litre is 1.98:1 and the ratio for the V6 is 1.65:1. You may not get a prop small enough to run on the 3 litre with the 1.65 drive.

Those drives use a dog clutch, they do grind when engaging. If you're 'easing' it into gear, stop doing that. You drop it into gear, single quick shift.

The noise you are hearing on reverse may be normal. With no load on the prop it may be just bumping on the backside of the dog clutch...

Chris.

Okay thank you very much! Yea no I do drop it into gear for sure!! Now I do notice some type of metal in the oil, not a lot but enough to notice! What's your thoughts on that? And if I were to change/check a seal if I'm not mistaken it's usually the one behind the prop?

 

[nola mike]

Okay thank you very much! Yea no I do drop it into gear for sure!! Now I do notice some type of metal in the oil, not a lot but enough to notice! What's your thoughts on that? And if I were to change/check a seal if I'm not mistaken it's usually the one behind the prop?

Some fuzz is normal, chunks of metal are not. There is no "usual" bad seal (why do you think you have a bad seal?), but prop seal is not one of the usual suspects...

 

[Spanky-05]

Some fuzz is normal, chunks of metal are not. There is no "usual" bad seal (why do you think you have a bad seal?), but prop seal is not one of the usual suspects...

Oh ok yea no chunks! Doesn't like to hold oil, and yes there is new o rings on the fill and drain plug I made sure to check that. I drained and put new oil in it twice last year and it definitely was needing it. The other year after I took it out of storage, got it home there must have been water still sitting in behind the prop because there was some that poured out when I was de winterizing it..... If that makes sense?

 

[nola mike]

Oh ok yea no chunks! Doesn't like to hold oil, and yes there is new o rings on the fill and drain plug I made sure to check that. I drained and put new oil in it twice last year and it definitely was needing it. The other year after I took it out of storage, got it home there must have been water still sitting in behind the prop because there was some that poured out when I was de winterizing it..... If that makes sense?

Yeah, but all that means it's that you have a leak somewhere. It will probably be easier to fix what's wrong than to swap parts around. The 4.3 will be a definite upgrade, but might/probably won't be plug n play in your boat.

 

[Spanky-05]

Yeah, but all that means it's that you have a leak somewhere. It will probably be easier to fix what's wrong than to swap parts around. The 4.3 will be a definite upgrade, but might/probably won't be plug n play in your boat.

Okay appreciate it, maybe start with replacing the seal behind the prop and go from there for the summer then look into swapping the bigger motor and lower unit into it in the winter after some more research. I do know they made the Capri with the bigger 4.3l in it, just cant if it was the exact model as mine type thing

 

[Spanky-05]

Okay appreciate it, maybe start with replacing the seal behind the prop and go from there for the summer then look into swapping the bigger motor and lower unit into it in the winter after some more research. I do know they made the Capri with the bigger 4.3l in it, just cant if it was the exact model as mine type thing

If it will fit with minor modifications like motor mounts I can do it. But I don't want to rip everything apart and find out it can't be done

 

[nola mike]

Okay appreciate it, maybe start with replacing the seal behind the prop and go from there for the summer then look into swapping the bigger motor and lower unit into it in the winter after some more research. I do know they made the Capri with the bigger 4.3l in it, just cant if it was the exact model as mine type thing

No, pressure test the drive, find out where the leak is

If it will fit with minor modifications like motor mounts I can do it. But I don't want to rip everything apart and find out it can't be done

Everything can be done with enough time and money. If they offered a 4.3 you might get lucky and have mounts there. I had to fab mine. You'll need a bit more width with a v6

 

[achris]

Okay appreciate it, maybe start with replacing the seal behind the prop ...

The prop shaft seals are the least likely to be the ones leaking.

Oil in the exhaust cavity is more likely to be drive shaft housing lower seals or shift shaft seal.

Before pulling anything apart, do a pressure test to know where you're going. I hate shotgun mechanics!

Yea no I do drop it into gear for sure!! Now I do notice some type of metal in the oil, not a lot but enough to notice!

Normal.

Chris...