I have this problem, every time I drive long distance - I would drive
for 2-3 hours fine and then when I slow down to get gas or food, I
would notice the very loud tapping sound from the engine, and then it
gets even louder if I step on the gas try to increase speed. It feels
like the engine has lost all its power when this happens.
If I shut the engine down for a while - 30 to 60 minutes or so, and
then start the engine backup, the noise would be gone. And this repeats
after I drive another period of time.
When I am in town driving around, it does not happen.
Last week I changed the Recirculation Exhaustion Valve (I think that
was what my mechanist called it) and he told me that (bad valve) was
what made the tapping noise when engine runs hot.
But it still happens when I drive on long trips. I check my engine oil,
coolant, all seems to be ok.
Any idea or advice will be greatly appreciated.