Installing Oil Seals the Proper Method

There is almost no information on shaft (rotary) oil seal installation.
The manuals have virtually nothing to say on this issue, except
occasionally showing an expensive special seal driver which is never needed
in actual practice.

Seals used to have metal outer rings, so all you had to do is keep it lined
up to the bore and tap all around with a hammer or block and it drove home
without difficulty. A little Permatex smeared in the bore would help seal
the ring to the bore.

Today, you see a lot of aluminum housings, and seal construction is rubber
coated to help in retention with heat coefficient dimensional changes.
Rubber coated seals can be tricky. Here are a few tips:

First test the fit of the seal to the bore. If it slips in with a hand
push, you're going to have trouble with rentention in service. Coat the
outer diameter of the seal and the inner diameter of the bore with Permatex
#1 and drive the seal in using a mallet and socket which is just a little
#smaller than the bore.

If the seal is a definite interference fit, then another treatment is
indicated. Prepare a soap and water solution, dip the seal in it and wet
the bore with the same solution. Then drive the seal home. After sitting
a while, the seal should be firmly in the bore. Try to pull it as a test
for fitment.

Rubber coated seals will tighten in their bores when the housing heats
because the coefficient of rubber is higher than aluminum.

Avoid using excessive force when installing seals as they can distort and
leak.

I have used the above procedure effectively and never had a seal work loose
or leak.