I hear a knocking sound that i presume comes from the front of my engine. I think it comes from the fan areaand it is itermitent. Anyone ever experienced the problem and if so, what is the fix?

 

I am having the same problem. I hear a knocking noise in the front end only when I am idling. I notice it the most when I am at a drive-thru because my window is rolled down. I don't think it is a value because it does it at random times. I went to my local mechanic the other day. When I pulled he heard the noise and said he hadn't heard anything like that before. Then the noise stopped. He wanted $72 dollars an hour to figure out what the problem was. Any ideas?

 

Its the fan clutch. Common wit this vehicle both Trailblazer and envoy. the knock only occurs at idle. If you give gas it goes away. Problem Is when vehicle is not yet warmed up I believe. Mine does it too. Friend had the dealer change his fan clutch.

 

bad idler pulley.

 

the problem is the fan clutch, my 02 Envoy made a pinging sound from the fan area for over a year only at ilde. Then one day it finally siezed. $1,000 dollars later at the dealer it is good as new. my car only had 26000 miles when it siezed.