hard to install valve stem seals
 

I'm doing a head gasket change on a 1987 Honda Accord 2.0liter fuel
injected engine.
Part of the procedure involves replacing the old valve stem seals with
OEM replacements, in this case. The valve stem seals that are giving me
trouble are the ones used for the exhaust valves, so there are 4 of
them. Now, removing the old ones was really really hard (it took hours
of pliers and prying with a flathead screwdriver), but installing the
new ones seems near impossible!

Is there a trick to this? What I've tried so far is lubricating them
with engine oil and then either pushing or twisting them on. I've
already destroyed one by hammering it in (they're made of a metal
sleeve coated with rubber, on the inside, which extends to a rubber
collar around the valve -- hammering on them made the rubber collar
tear).

Another approach I tried was to use a 10mm socket, which fits pretty
closely on top of the metal sleeve, but does not touch the rubber
collar, and a rubber mallet to hammer on it. This has worked better
than the mallet directly onto the seal, which was disastrous, but I
still worry that it will weaken the collar enough for the seals to fall
apart sooner rather than later... Worked better in this case means I've
managed to get one out of four in!

The honda shop manual and the chilton manual say nothing about proper
installation procedure, yet this seems like the sort of thing where if
you fatigue the part during installation, it fails spectacularly later.


So, has anyone had experience with this? How do people get these on?
Should I perhaps try heating the seals?

Thanks!
Teri