Help identifying a part

[jmwj03]

I have an '86 Mon Ark with a 3.0 OMC and OMC outdrive. I have the motor and outdrive pulled to repair the transom. While out, a neighbor (who knows a lot more about this than me) suggested I change something and I don't know what it is.<br /><br />He was looking at the motor with my brother-in-law (I wasn't there) and when he looked in the rear of the motor, through the bellhousing, he said to change the "hub" that the splined shaft from the outdrive goes into. It appears to be some kind of bearing that the shaft goes through to mate with the motor and is surrounded by rubber (according to my brother-in-law.)<br /><br />I have 3 questions:<br />1) What is this part called?<br />2) Is it as straight forward as pulling the old one and pressing in a new one?<br />3) Most importantly, what should I expect it to cost?<br /><br />Thanks, and sorry if this is a stupid question!

 

[P.V.]

Re: Help identifying a part

There is a coupler attached to the flywheel on the back of the motor. It accepts the input shaft (splined) from the outdrive. The coupler has a rubber hub that absorbs the shock of the boat/prop zooming around the lake and shifting,etc... Inside the transom bracket, there is a support bearing (gimble) that supports the heavy weight of the u-joints/input shaft. You can reach in and grab/turn the gimble bearing. If it's rusty or feels rough to turn, it needs replacing. But don't replace the coupler (pull out the motor) unless it needs to be changed!!!

 

[jmwj03]

Re: Help identifying a part

Thanks PV!<br />The motor's already out. The coupler is what he is talking about. He says it needs changing...I don't know why, he just said it would go out before much longer. He's replaced the coupler in his past 2 boats so maybe that's why. I already have the gimbal bearing, but this part was throwing me. Thanks again!<br /><br />If I change it to be safe, what kind of money am I looking at?

 

[deckhand]

Re: Help identifying a part

Your friend is probably looking at the condition of the splines inside the coupler. If they are sharp points they are wearing due to engine/gimbol bearing mis-alignment. This causes the drive input shaft to wobble inside the splines and wears the aluminum splines out. The coupler is around 300.00 and it is a straight bolt on, however once you get the engine back in take it to a dealer and get it properly aligned before putting drive on- otherwise problem will come back! I do not think you want to buy an alignment tool is why I say take it to dealer.

 

[jmwj03]

Re: Help identifying a part

Thanks guys! I'm trying to locate the part now. Let me ask a question...I am going to replace the U-joint while the outdrive is removed...can I use that shaft for alignment rather than the actual alignment tool? That's what I used to do for clutch alignment on vehicles. If not, off to a dealer I go!

 

[achris]

Re: Help identifying a part

The engine alignment tool is not the same as the input shaft. Suggest you get it done with the right tool. I have run stern drives for over 18 years and have never had to replace a coupler. I bought the tool and check the alignment ever few years when I'm doing a full leg service. The other thing worth checking if the coupler is chewed out are the rubber mountings at the back of the engine (on the flywheel housing). If they have sagged then you can't get the alignment right.

 

[jmwj03]

Re: Help identifying a part

Thanks for the help! I am going to look at my motor tonight and get some numbers. I have no problem finding the Mercruiser couplers, but not much luck with cross references to OMC. Is there a list somewhere that will tell me what to ask for? I'm also trying to find a local shop that will align it, but the few I've called can't cross the coupler without seeing it.