Re:Low compression 2 liter

[Biba <biba@xxxxxxxxxxxxx>]

******************************
I have a 2 litre engine with low compression (120 - 130psi) in cylinder
#1.  I
poured oil in the cylinder and the compression jumped up to the 180s and

dropped as the oil was blown out the valves.  Simple, its the rings.  I
pulled
the head, dropped the sump, and pulled the #1 piston.  The rings looked
like
they were spaced correctly.  There were no obvious marks or anything
else that
would point me elsewhere.  I've had this problem since I built the
engine last
summer.  I haven't put that many miles on it, probably less than 5000.
Should
I align the rings at 10, 2, and 6 and put it back together or is there
something else I'm missing?  Thanks in advance.

Lawrence Gowin
********************************

Lawrence, while 120 to 130psi isn't terrible, my guess is the rings
never seated properly. What I would do: First I'd pull the engine and
strip it. Take the block and pistons to a qualified automotive machine
shop and have them measure both the pistons and liners before
proceeding. Chances are the pistons will be okay, but liners have a
tendancy to wear at the top. If they feel new rings won't fix the
problem, replace as necessary. Assuming liners and pistons are reusable,
have them hone the liners (Shankle, for one, has information as to what
hone to use depending on what rings you use), and I'd use Deves rings
because they are the easiest to seat. My machinist doesn't like them
because he feels they're too rough on the liners. The instructions that
come with the rings will tell you exactly how to place the rings. The
oil ring is 4 piece. Make sure the pistons are pristine first (no
carbon), but don't get too carried away cleaning. You'll find the piston
ring compressor will have to be as tight as you can possibly get it as
the bottom thin oil ring really wants to slip out. I keep tapping on the
ring compressor until it sounds solid all the way around, then start
with a fairly firm tapping in the center of the piston dome with the
handle of my (small) hammer. If it won't start, chances are the lower
ring has slipped out.

Everyone has their own theories as to how to break in a fresh engine.
Mine is to not let it idle anymore than you need to as the gas washes
down the cylinders and polishes them. You don't want to do that ever,
even after the rings are seated in. I understand you'll no doubt need to
make adjustments to get it running properly, just make them quickly.
Then drive the car slowly, stop and check for any leaking fluids, if
okay continue on taking it up somewhat higher (rpm) then back off
completely - make sure it's safe to do so of course. As the car begins
to loosen up slightly, take it out on a highway at night and take it up
a little higher yet and back off. If done right, those rings will be
seated within 50 to 100 miles, easily.

Should you be a synthetic oil guy, don't use it for the first 500 miles.
Then re-torque the head and change oil and filter and go ahead with
synthetic if you wish.

Biba
Irwindale CA
AlfaCyberSite - http://home.earthlink.net/~biba/

------------------------------