I recently replaced the head gaskets on my 97 Chevy Venture (3.4L V6).
When I put the rocker arms back on, I torqued them down per the
instructions in my Haynes manual. At the time I was concerned because
some of the rocker arms seemed looser than others. When I started the
van, I could hear a clacking sound. My uncle tells me I need to find
out how to do a "valve lash" adjustment. What steps should I take
when installing the rocker arms in this engine?
If the engine runs, then just back off the adjusting nut (one at a time)
until it starts to clatter (this is zero lash). Then SLOWLY tighten
down 1/4 turn at a time until you have gone 1-turn. Do this on each
To do it without the engine running, position the engine to fire #1
cylinder and back off the adjustment until the pushrod rotates freely.
SLOWLY tighten the nut until resistance is felt (ths is zero lash) then
SLOWLY tighten the nut 1-turn farther. Do this to exhaust on cyl. 1, 5,
6 and intake on cyl. 1, 2, 3. Then rotate engine into position to fire
#4 cylinder and do exhaust on cyl. 2, 3, 4 and intake on cyl. 4, 5, 6.
There are two classes of pedestrians in these days of reckless motor
traffic - the quick and the dead.
~ Lord Dewar 1933 ~
Climbing into a hot car is like buckling on a pistol. It is the great
equalizer. ~ Henry G. Felsen 1964 ~
There is no "valve lash" adjustment on these engines. One of two
things has happened. Perhaps 3 things. One, you mixed up the
short and long pushrods (short pushrods go on the intake valves,
long on the exhaust valves). If you did do this...and you run the
engine for any length of time, you can do some major damage to
Two, you didn't get the rocker arm pedestal down into the cylinder
head properly (both the head and rocker arm pedestal are notched,
cylinder head is the female side, pedestal is the male side) and so
even though you have the rocker arm torqued down, it's not actually
all the way down.
Three, sometimes, it's completely normal for the lifters to either
pump right up and when you start the vehicle, it seems as though
there is no compression, or they "won't" pump up right away, and
you end up with lifter noise until the engine warms up a bit. This is
usually due to the coolant that has been running around in the engine
oil. Dexcool makes a scummy brown sticky coating that gets all
over the inside of the engine and the internal parts of the engine.
Hopefully for you, it's either 2 or 3.
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