Help 96 SL-2 no compression

Hi all

I have a 1996 Saturn SL2 143,000 miles. Was running fine not a
problem. Then Yesterday morning I started it up and the engine
had a miss. Ran rough. Figured a wire plug or pack. Drove it over to
the local shop. He found 0 compression in the #3 cylinder I mean
0 . Shot some oil in and the compression was still 0. Took the valve
cover off all looked fine nothing broken. He is not sure what's wrong
at this point. Whole in piston a valve ??? Compression good in other
cylindesr. So no bridge between cylinders. Remember the compression
gauge did not move. Any Ideas without pulling the head.

Thanks Ron

 

Did you check for a stuck valve? From what you say it began after it sat
over night so that would be the most plausible thing to occur.

 

How would you tell if the valve is stuck and how would
you get it unstuck. The shop had the valve cover off
and saw nothing abnormal.

 

There wouldn't necessarily be anything to see if the engine was stopped.

In order to make sure that the valve train is working properly, you need to
watch it while the engine is turning (being cranked by the starter, not
actually running) and make sure that all the valves move the right direction
at the right time.

Having said that... I've never heard of a valve just "getting stuck". The
return spring is pretty damn strong. I've heard of valve springs breaking.
I've heard of valve lifters breaking, and hydraulic lifters collapsing.
(Not an issue on a Saturn, with an OHC engine.) I've heard of valves breaking.
But I've never heard of one just getting stuck.

A broken valve spring *should* be visible with the valve cover off. Depending
on where and how it broke, though, it might be pretty hard to see unless
you're looking in exactly the right place. At least you know which cylinder to
look at.

There's another explanation for the problem, too, but you don't want to hear
this: broken piston rod.

 

He will have to watch to see if the valves ride up against the cam on
that cyclinder. (Disconnecting the coil pack would be a very wise thing
to do since the coild pack wont be grounded.)

Springs on multi valve engines arent very strong as the valve surface
area is much smaller. Doesnt take as much to seal. On a SL2 it will be a
DOHC engine which will look like this

A SOHC SL1 will have rocker arms and you can see their springs.

A broken spring is very possible. It would allow the valve to pull up
away from the piston just enough to clear but never fully close with the
cam lobe.

From sitting overnight? Eh not likely.

One other test is to pressurize the cylinder with shop air to find out
if it blows out of the intake, exhaust, or head gasket. Piston has to be
TDC of course.

 

I had this happen in the same year and model. It turned out to be a piston
with a big piece broke off the top of it.

Ken

 

May I be so ignorant to inquire what a misfire sounds like/ how you know
your engine has done this?

My Saturn is my first car.

 

My Saturn 'stumbled' in a start up, flashed the SES and then went
solid. I had the code checked, and it was something like "engine
misfire". After that, everytime the car started rough, stumbled, and
the SES light came on, I figured it just misfired.

So all I say, if you hear a stumbling, and see the SES, you might have
a misfire.

later,

tom @ www.NoCostAds.com

 

You newver mention if the technician perform and cylinder leakage test.
He would be able to erify if it is the valves/rings/head gasket/ head
leaking. All that can be done without the valve cover taken off.

 

You newver mention if the technician perform and cylinder leakage test.
He would be able to erify if it is the valves/rings/head gasket/ head
leaking. All that can be done without the valve cover taken off.