You could measure across the flats. It's a SEA (inch) engine. The next
smaller from 13/16 is a 3/4"

JoBo

> wrote in message
ps.com...
> Hi all
>
> I am trying to change the rear main seal in my 1997 4.0 Jeep Grand
> Cherokee. I have been pretty much over my head in the whole project.
>
> In trying to remove the main cap, my 13/16 socket seems too big, and my
> 20mm socket won't fit on the main bearing bolt.
>
> Does anyone know what size these are? At first, I thought the 20mm
> socket just needed to be deeper so I just got back from the store with
> a deep socket and it doesn't fit on either.
>
> I do not have a factory manual.
>
> Thanks in advance.
> Doug
>