Engine knock and smell of gas

Hey there, I own a 97 Monte carlo z34.....The car developes a knocking sound from the engine compartement after having been driven for 1/2 hour or more, and then "only" when I stop at a light or put it in
park. I can even feel the knocking vibrations through the brake pedal. The car runs perfectly otherwise, it idles very well and has good power. Funny thing too, sometimes the knocking sound continues for 5 - 10 seconds even after I have shut off the engine. I have also noticed a faint smell of gasoline within the car and outside in front of engine when car is running, not sure if it has something to do with knocking. The car has recently had head gaskets and water pump changed due to overheating problems...........thanxs in advance for any help......
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"ludwig" wrote: 97 Monte carlo z34.....
The car develops a knocking sound from the engine compartment after having been driven for 1/2 hour or more, and then only when I stop at a light or put it in park. I can even feel the knocking vibrations through the brake pedal. The car runs perfectly otherwise, it idles very well and has good power. Funny thing too, sometimes the knocking sound continues for 5 - 10 seconds even after I have shut off the engine. The car recently had head gaskets and water pump changed due to overheating problems. ________________________________________________________
There is probably still an overheating problem. These symptoms can occur if the radiator is blocked, the heads are cracked, the thermostat is defective or the thermostat is installed backwards. The knocking would be bursts of superheated steam in the engine block or heads.
Wendy & John. ________________________________________________________
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ludwig wrote:

You might want to start by checking the fuel lines and their routing. Sometimes you can get that sort of noise from the fuel lines if they are grounded out against a component that travels inside the car.
Ian
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