Heath

I recharged the ac system and so far the popping has subsided. We shall see in the coming days if being low of Freon was causing this sound.

I have read not to use stop leak and saw some mechanics video saying do not use the products. The popping sound is more along the lines of the sound of the old carburetors popping sound way back when. I had all the blendors replaced last year and I am familiar with the popping sound they make. 'the sound comes from under the hood I am almost positive. Thanks Heath

I have a 2004 GMC Sierra 5.3 Crew Cab and I have had A Popping sound coming from either under the hood or in dash. It's apparently a release that's not happening and pressure is building and releasing at once when I start the motor with AC on or just turning it on while driving. Just wanted to see if anyone has had this problem and see what the cause may be. Also I am losing Freon over several weeks as well and I have read where some mechanics DO NOT recommend using any stop leak products in the system because it will cause other parts to gum up. Any thoughts on this as well? Thanks for any input you may have for me!! + Heath

Thanks for the quick response! I'll look at rear rotors next! Heath

I recently noticed that when I am breaking, especially from a high speed, that i have a shimmy in the truck. The first action I took was replacing the front rotors and pads but still have some shimming taking place but better. Does anyone know if there has been a case where the master cylinder caused this problem? It's sometimes makes it feel like I'm pumping the brakes, that is why I'm asking. The only other thing i know to do is change the rear brakes and rotors. thanks Heath

I have the knock sensor gm part number- 12589867 the model truck I have is a 2004 gmc sierra 5.3 L

I'm looking for part numbers for gm knock sensor and wiring harness....If anyone has information on these please let me know.

Good Morning, I wanted to see if anyone has knowledge of the knock sensors in the 2004 GMC Sierra 1500 5.3 models and what they affect when failing? My light started coming on last week and the mechanic says the intake has to be removed to get to the sensors. Just want to know how serous an issue this is to be corrected. Thanks Heath

I change my truck every 3000 miles. I also own a 2008 Toyota Sienna and use Conventional and change it at 3000 but I'm going 100 % Synthetic with both vehicles now, 2008 Nissan Altima and I use Mobil Synthetic (that's what previous owners used)and change every 5000 and a 2010 Toyota Camry and I use Valvoline Synthetic (previous owners used Havoline Synthetic) and change every 5000.

Ok I want to throw this out there to you, what's your opinion on using Conventional Motor oil. My mechanic changed the valve cover (2004 GMC Sierra 5.3 crew cab) and showed me where the issue was on the pcv valve and blamed it on the conventional oil and has convinced me to changed to synthetic oil. I've used Valvoline oil and now I'm going to Valvoline Synthetic. Here's my real question, he is encouraging me to add Lucas oil treatment on top of the 6.5 quarts of oil and I said that'll overfill it. He said it won't hurt it but I said I've always understood it's worse to have an engine overfilled than to be a little low. Please give me your thoughts....

I recently met a friend from visiting another church where my daughter goes to school and we discovered we owned the same 2004 GMC Sierra year model. In discussing our trucks he told me his truck was low of oil at 3000 miles at oil change time and a young mechanic told him that the left valve cover is where he is losing it. He had it replaced and problem solved! Anyone else about a quart low at oil change time?

My 2004 GMC Sierra SLT 4x4 had the ABS issue stated in other post on this subject where the abs motor started kicking in (when slowing down and hitting the 10 mph to stopping) shortly after I had abs light coming on randomly. First thing done was followed the code reading and changed the driver side sensor wire and that didn't solve the problem. Second step was checked for bad wheel bearings, all bearings seemed in good condition. Third move was run computer code 0269 to think all wheel sensors needed cleaning and the surrounding areas. So I got online and ordered another front wheel sensor so mechanic could changed front passenger side in the process of cleaning the hub (and he did find a Knick in the sensor wire that could have been a problem). First one I bought at Oreilly's for $60 versus the one I bought online at AM-Autoparts.com for $15. He cleaned each wheel hub sensor and reluctor rings and this solved my problem. Hope my post helps someone who encounters this issue.

Thank you Matt for taking the time to respond with valueable information to save me money and time to solve my truck issue! I will pass this on to my mechanic.

Did you ever get any solution on this abs problem? I'm having it with my 2004 GMC.thanks in advance!