| Re: [GMCnet] Noisy Lifter [message #107650] |
Mon, 06 December 2010 06:17  |
Gary Casey
Messages: 448
Registered: September 2009
Karma:
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Senior Member |
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Yes, a exhaust gasket leak can sound like a lifter ('tck, tick tick" at idle).
The easiest way to eliminate that possibility is probably to disconnect one
spark plug at a time - when you get to the right cylinder it will go away.
Since you already know the approximate location that shouldn't take long.
Don't let it run for a long time with the wire disconnected as the coil is
highly stressed when doing that unless you ground the wire.
There are a number degrees of lifter problems. The most common is a minor
leak-down, which results in a ticking sound after starting. Generally
occasionally and after the engine has sat for a while. It goes away after a few
seconds of running. Annoying, but I wouldn't spend a lot of time trying to fix
it. The second stage of a leaky lifter is one that also always leaks down at
idle, especially when hot and the oil is thin. It goes away above idle as the
oil pressure rises and the time available to leak down is less. Again, annoying
and something that doesn't have to be fixed, at least not right away. Instead
of leaking, a lifter can get stuck in position and in this case will make the
noise pretty much all the time, although you might not hear it at high speed.
I'd want to figure this out and fix it, as the impact in the valve train will
eventually cause damage. The first step to fix it might be to put in one of
those oil additives that claims to fix anything. They contain a strong solvent
that just might loosen up a stuck lifter. Make a dance around the coach, a few
appropriate gestures, cross both fingers and hope for the best. Probably won't
work, but worth a try anyway. Before taking the engine apart you might take off
the valve cover. Do it right after running the engine (take out all the screws
leaving the cover in place. Run the engine for a minute and then pull off the
cover.) If one of the rocker arms shows play, you've found it. You might have
to repeat the test a few times before the engine stops in the right location.
Check the tightness of the rocker studs - they just might have left one loose.
If this test comes up negative, it could still be a stuck lifter. Run the
engine with the cover off (this will be messy, as you will get oil on the
exhaust) and feel each rocker arm. You will probably feel the "impact" in one
of them. After you find out which one it is, you can pretty much forget about
that - it will be about as easy to remove and repair all of them as just one.
This requires the removal of the intake manifold, not fun. Then all the
lifters can be removed and "rebuilt", which means disassembly, cleaning and
checking the leakdown rate.
Hope that helps - FWIW
Gary Casey
Michael.
"lifter noise" may be something to be concerned about. I would first want to
determine the actual source of the noise.
On a day when you hear the noise use a piece of rubber hose (a 2-e foot length
of heater hose works well) as a stethescope and listen to the engine to locate
the source. Do NOT hold the end of the rubber hose in your ear but near the ear.
Initial clicking noise on start up may be valve train or it may be elsewhere --
Dennis
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