A-Mercruiser I-Drive Unit: pre-load required?

[YOBE]

Hi,

Serial nr engine: 4506302.
The 165HP 6cyl in-line.
Based on the service manual and checking the upper unit of the stern-drive I have the "A-Mercruiser I-Drive Unit", some call it MC1 I think (the unit with the pin on the top of vertical shaft) it has no Pre-load.

I need to replace the main Oil-seal on the upper drive assembly.
On the forum and internet I read a lot about preload and the "special" washer. (with the NUT marking).

Now when I read the service manual nothing is mentioned about this for my unit. Just the end-torq of the nut. When I dissasembled it the nut was also firmly tight.

I see in later versions of sterndrive like R-MR-Aplha 1 they indeed speak about the pre-load in the service manual, but NOT on mine.

Could it be possible that for my sterndrive this was not yet applicable?

Regards, Yorick

 

[Pmt133]

If you're talking about the nut on the end of the yoke for the input shaft in which the gear set under the top cap is affixed to, the preload is set by initial shimming of the drive and the final torque of the nut. In later years it is set by measuring rolling torque. In your case, disassemble keeping parts in order. Replace seal, install seals and bits back on the yoke and torque the nut. Nothing else should be needed.

Also, you may need a speedy sleeve for the sealing surface. They tend to groove.

 

[YOBE]

Thanks!
This confirms what I expected. Certailly when I inspected the original washer there was also not marking of "NUT" on it. (but you never know who messed things up before)

So, clear now. Thanks for the feedback.

 

[kenny nunez]

The washer should be slightly ‘cupped”and you see where the nut contacted it so be sure to put some Loctite on the threads. The nut marking was not on the washer on the real early models.