Whats the hype with the CASTLE plug on the front case?

[SnowBird]

I have removed my front case/oil pump several times and swapped it over to different engines and although the manual says to remove the plug and replace it I never have. I have never seen a reason to remove it for anything and it has never leaked. I have a 1990, does it need to be removed on other models for some reason?

I just always see posts about people needing to know where to get one, then I realized Ive never taken it off during front case removal because Ive never seen a reason to.

 

[knochgoon24]

People take it off to remove the balance shaft and replace it with a stubby shaft.

 

[need2boostpsi]

the castle nut is the plate that covers the oil pump sprocket, it has a rubber o-ring that hardens and leaks if not replaced, better to do it while its out then tear the timing cover off for a 25 cent o-ring.

 

[shredwin]

I removed mine just to replace it with the stubby shaft but I didnt change the castle nut plug, I reused it and it doesnt leak at all.

 

[SnowBird]

Maybe mine is different from you guys's, I removed my balance shafts, installed a stubby shaft and never had to touch the castle nut. I have a 90, one of you said it covers the oil pump sprocket but I dont see how, the oil pump sprocket goes on the outside of the cover.

Im guessing with the cover removed you can pull out the balance shaft and replace it with the stubby and then slide it back in? I did my stubby shaft and balance shaft removal with the engine out and the case off, maybe thats why I never had to touch it, when I did the stubby I took the plate off the oil pump on the back of the cover.