Chevrolet Repair: valve tapping, valve lifters, valve lifter

Question
I have a 2000 Suburban with the small v8.  When the vehicle has been setting for 5 hours or so and the temperature outside is below 50deg F there is a tapping sound when I start up. It last for a  minute or so. if I put the truck in drive (or R) and start to move it gets loud.  It almost sounds like a diesel.  It just started this after my last oil change.  I have changed the oil every 4-5k and have owned it from the beginning. There are 114,000 miles on it.  Is this serious?

Answer
If it is ONLY valve tapping this could be a sign of :

1. A faulty valve lifter and or a piece of debris is stuck in the lifter and may eventually flush itself out. If it continues to get louder you may have to replace it.

Other causes could be:

1. A worn rocker arm.

2. The top of the valve stem is worn.

3. A broken valve spring.

There are additives that sometimes work and sometimes not that you can add to the engine oil. One is an agent that is supposed to clean the valve lifters and remove any foreign debris that may be stuck in them

Another is STP or similar product that leaves a heavy coating of oil on the rocker arm shaft assembly.

Without really hearing this noise an exact cause is impossible to say.

Your best option is to have a local facility simply remove the valve cover and have a look and a listen.


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