mercrusier 350 MAG MPI coupler problem

[jfp923]

Hello all.
We bought a fixer upper a 2001 Bayliner Ceira 2855 with a 350 MAG MPI (sn# 0M082316) and a Bravo 3 outdrive (sn# 0F807380). Engine runs great, I replaced the gimble bearings and aligned the engine, but while doing that I notice the drive coupler spline looks like it is missing the first inch of spline. The rest of the spline looks fine. How does that happen? Is it safe to use that way or should the drive coupler be replaced? Thanks for any help you can give me.
Joe

 

[flashback]

I had the same question a few weeks ago, the splines don't go the entire length of the coupler.

 

[Bondo]

Ayuh,..... Welcome Aboard,....... The splines are 'bout maybe 3", same as the spline area of yer alignment bar,.....
The splineless area is sorta a guide to bring it all home,.....

 

[jfp923]

Good morning,
Thank you for the previous answers.
I did some more checking and I measured the distance between the coupler spline starting point and the outside of the gimble bearing and it is 9 3/8". The spline looks to be closer to 2" in from the end of the coupler hard to read threw the small hole. The length of the yoke on the outdrive is 9 1/2" from spline end to flat part, which I assume must ride up against the bearing. I would think the yoke should go in far enough to use the whole spline in the coupler, am I right? Seems to me someone must have changed the outdrive and it had a shorter yoke on it. I looked on line to find the sizes but was unsucsseful. Can anyone help me with that?

 

[Bondo]

Ayuh,..... There's only one length of shaft,....

There was a shorter shaft used back in the '70s for in-line GM motors, 'n the MC-1 drives,....
'n it was 'bout an inch shorter,....

 

[jfp923]

Ayuh,..... There's only one length of shaft,....

There was a shorter shaft used back in the '70s for in-line GM motors, 'n the MC-1 drives,....
'n it was 'bout an inch shorter,....

So is it a bad design I have to live with? From the repair history I got with the boat this will be it's third drive coupler. Seems to me that it won't last if it does not go into the drive coupler all the way or at least more than an inch.

 

[Bt Doctur]

with proper alignment and maintence it will last a long time

 

[nola mike]

So is it a bad design I have to live with? From the repair history I got with the boat this will be it's third drive coupler. Seems to me that it won't last if it does not go into the drive coupler all the way or at least more than an inch.

I'm guessing that the yoke wouldn't bottom in the coupler to allow for engine/u-joint movement.

 

[Scott06]

So is it a bad design I have to live with? From the repair history I got with the boat this will be it's third drive coupler. Seems to me that it won't last if it does not go into the drive coupler all the way or at least more than an inch.

If the alignment is correct the coupler will last the lifetime of the boat. If this is the third coupler there is an issue that needs to be fixed either transom engine mount of stringers are damaged, someone is hitting stuff or running over anchor lines, or alignment is off.

Were these OEM merc couplers or aftermarket?

 

[jfp923]

If the alignment is correct the coupler will last the lifetime of the boat. If this is the third coupler there is an issue that needs to be fixed either transom engine mount of stringers are damaged, someone is hitting stuff or running over anchor lines, or alignment is off.

Were these OEM merc couplers or aftermarket?

I haven't had it in the water yet. Still making repairs. I don't know what the previous owners have done I do know they repplace the coupler when they bought it. The new parts I have bought are only OEM. The transom and stringers are in great shape. It just seems that if merc is going to make a coupler with 3-4 inches of spline in it the yoke should go in most of the way. The spline in the coupler looks like it is in 3 sections, the first one only about an inch long. Which is about how far the yoke will go into it.

 

[Scott06]

I haven't had it in the water yet. Still making repairs. I don't know what the previous owners have done I do know they repplace the coupler when they bought it. The new parts I have bought are only OEM. The transom and stringers are in great shape. It just seems that if merc is going to make a coupler with 3-4 inches of spline in it the yoke should go in most of the way. The spline in the coupler looks like it is in 3 sections, the first one only about an inch long. Which is about how far the yoke will go into it.

Make sure you have the correct input shaft (only one I knew was shorter is the older inline six ones) and alignment is good and it will work.