Mystery part on drive shaft

[Bgbbgb246]

While pulling a Powerhead off of a 25 inch midsection to put it on my 20 inch midsection I found the part pictured on the driveshaft between the Powerhead and mid section. Out of my own stupidity, i took it off to inspect it and forgot what direction it was on the drive shaft. I cant find the part in oem diagrams i find online and i dont have a manual. I guess what mostly confuses me about this part is that i dont understand how it would stay in place if you took the lower unit out to do a water pump or something. How should I reinstall? Should it have come off at all? Is it supposed to stay on the powerhead?

Maybe a very simple question to answer so I’m sorry for asking it but not knowing what this part is called makes it very difficult to search. Powerhead is from a 2000 2.5L 150 efi

 

[Dukedog]

that is a seal that goes in tha end of tha crank.. its got a different name that doesn't even resemble tha term "seal"! if it comes out when removing jus tha gear case you will not be able ta put tha gear case back on till ya get it back where it goes and that my friend can be a real PIA........ so NOW is tha time ta fix it...........
when you replace it make sure tha inside of tha crank surface is as clean as possible then put a touch of red loc tight on tha "outside edge of tha seal casing surface (tha part that actually sticks "inside" tha crank)..

part number 54196A6

CARRIER ASSEMBLY​

JUN... those splines don't look so good!.. check tha ones inside tha crank.

 

[Bgbbgb246]

From the way your explaining the re assembly, it does sound like i have it on the shaft in the correct direction so thats good.

So your saying there is enough vertical space between the bottom surface of the crank shaft and the top surface of the mid section when the powerhead is installed for this part to become dislodged from the crank shaft when removing the gear case down the road? Man thats a bummer.

If the above is the case i suppose after i put the red loctite on the outside edge of the seal, i should probably make sure it stays in the crank shaft untill the loctite cures before i install the powerhead on the mid section (and splines of lower unit)?

Lastly since it was menioned id like to touch on the splines of the drive shaft. I bought this lower unit just recently used. The lower unit that i took my new powerhead off looks almost perfect and the splines inside the crank on the powerhead look good. (My new to me powerhead has never been on the lower unit pictured above) This all being said i dont really have the money to buy another lower unit currently. Is the seemingly very used lower unit with its worn splines going to hurt my much less used new to me power head? Or can i run it for a while?

 

[Dukedog]

"So your saying there is enough vertical space between the bottom surface of the crank shaft and the top surface of the mid section when the powerhead is installed for this part to become dislodged from the crank shaft when removing the gear case down the road? Man thats a bummer."

yes... if ya notice tha hole for tha drive shaft in tha adapter plate is smaller than tha dia. of tha seal....

"If the above is the case i suppose after i put the red loctite on the outside edge of the seal, i should probably make sure it stays in the crank shaft untill the loctite cures before i install the powerhead on the mid section (and splines of lower unit)?"

yes.

you might "clean up" tha splines on it some and run it like it is since its not gonna be ona stem winder (hot rod) type rig!

"

 

[merc850]

Grease the splines at least once a season before you spring launch.

 

[Faztbullet]

Just stop at an auto supplier and get ya some of the lil CV joint grease packs. Great for splines