I have a '90 Grand Marquis 5.0. The water pump, thermostat and all
hoses were replaced approximately 5 months ago.
Today, while riding on the highway, it is 100 degrees in NYC today, my
temp. gauge is fine until out of nowhere it rises to 3/4's of the way
up after riding for around a half hour with the gauge only 1/4 of the
way past the "C", where it always is.
The car did not overheat but the gauge stayed up there. When I finally
got to my destination and parked the car, before I shut it down, I
hear a knocking sound, which I never had. It does not sound like it is
coming from the engine, it sounds like it is coming from somewhere
around the engine. I know it is impossible to explain a sound.
To make a long story short, if I let the car cool down and start it up
the knocking goes away. If I get it real hot again the knocking comes
I went to my mechanic and he was very busy and couldn't take my car
but he said that it sounds like it could be the "air pump" since the
water pump and thermostat were new, of which I know nothing about.
I drove home and the same thing happened with the temp. gauge and the
knocking was back when I got home. Waited about 20 minutes, started it
up and no knocking.
Any ideas anyone? Can the air pump be responsible for this?
Thank you very much for any replies in advance!!