The head gasket blew on my ’97 Neon
twin cam engine). I replaced it, using
one of those new layered-steel gaskets. I
also had the head shaved a few thousandths
at a local machine shop. I have the book and
the instructions that came with the gasket,
and I followed all the steps religiously.
However, as soon as I started it, it sounded
like a bucket of bolts and misses badly. In
speaking to a few local mechanics, they all
are pretty sure I screwed up the timing belt
installation and bent some valves. Assuming
I take it apart and find this to be true, how
can I prevent this from happening again?
Unfortunately, that factory service
manual’s pretty poorly written. Not only is
the text and graphics unclear, some of the
procedures it describes are ridiculous.
What can happen is that, during belt installation,
a combination of valve spring pressure
and engine compression can suddenly move the
cam(s) and/or pistons into a position where the
valves are bent. And they bend very easily, this
is a “Swiss watch” powerplant. Even if you move
everything back into alignment, double-check
the valve timing, etc. If the damage is done, your
goose is cooked!
Here’s how to prevent this next time:
Simply omit the rocker arms until the belt is
installed and tensioned. What I recommend
is even cranking the engine a few dozen
revolutions (starter motor OK) and triple-checking
that the TDC mark and sprocket
alignment notches remain in alignment. Then
simply pop the rocker arms in using a large
screwdriver (see photos, above). Some guys
like to use one screwdriver to compress the valve spring and another to pop the arms in, but I find that one’s all you really need. Place the tip of the arm over the valve stem and under the cam lobe, then pry the opposite of the arm up, compressing the valve, and lever it onto the lash adjuster’s tip.
If you don’t have them already, now’s a great time to swap to the later “bleed hole” anti-pump-up type lash adjusters and stronger rocker arms from ’00-up 2.4Ls.