What might cause this sound?

[jgarcia408]

Hi folks. I have a 2004 Vibe and theres a sound that I cant identify. Im not mechanically inclined so I have no idea what might be causing it. Im hoping someone here might have some idea what might cause this.The sound I hear occurs when ever I press the gas. It sounds like a quick rattle, but stops after the initial press on the gas. Its noticeably louder when I press the gas and am going in reverse and MUCH louder when I have the AC on. When I have the AC on and I press the gas, the sound is more high pitch then when I dont have the AC on. Again, it only happens when I first press the gas. Once I press the gas and I hear the rattle for maybe 1 second if I keep my foot on the gas to keep my speed or to accelerate I dont hear the sound.I can take my car to the shop to get a diagnosis, the problem is Im pretty low on funds and just the diagnostic alone is of course going to cost me. I am just trying to figure out what to expect once I do go to the shop in terms of costs and whatnot. I know that all depends on where I take it, but I can at lease get a general idea if I have some clue as to what might be causing this sound.I appreciate any help that you all can provide.

[djkeev]

Boy, that's tough diagnosing sounds via keyboard! That being said here's a few things to check.On initial acceleration a lot of stress is put on the fan belt (actually not driving a fan, they're electric, but we still call it a fan belt). It goes from idle to a high speed instantly. If the belt is severely worn or damaged, or if it loose for some reason when the crankshaft pulley suddenly picks up RPM (when you depress the gas pedal) there is a period of slippage before the belt gets up to speed with the crank pulley. This creates a squeal that can last but a second, or continue for a period of time.There is a bearing that keeps tension on the fan belt, these go bad quite often and can be a constant noise or (like the slippage) only happen under stress and make a rattle, a rumble or even a squeak.Loose exhaust clamps or hangers can make a noise upon speed change. When you depress the gas pedal the engine revs up and it twists on it's mounts. This twist causes the exhaust system to move a little and if any mounting, clamping or heat shield is loose it will rattle. Often this noise will indeed get worse in reverse for you've suddenly changed the entire torque put on the transaxle and it's mounting.Catalytic converters and mufflers can have the internals come loose and while the unit doesn't leak exhaust, it does indeed rattle about within the outer shell.Now, let's get into more $$'s and more work.Standard transmission? Your clutch could be going out or internal problems may exists.Automatic transmission. Torque converter, clutch packs, hydraulic controls may be going bad on you.Drive axles often click under hard stress such as acceleration. The constant velocity joints are made up of engineered pockets and large metal balls which allow them to rotate and flex. When the wear the Balls have play withing the sockets and will make a noticeable clicking sound under stress such as acceleration or sharp turns. In reverse, you've again changed the way the balls react with their pockets and noises can be more pronounced.Broken motor mounts can also cause odd noises for the engine is now loose in the engine compartment and allowed to twist in ways it was never intended to twist. Things can rub against the body and also change the entire geometry of engine // transaxle to to exhaust, drive axles, etc.Good luck. I know this is broad and vague but it gives you some ideas on where to start looking.Dave

[jgarcia408]

Thanks for the reply. Well everything said makes me a little nervous, simply because with each item you mention I see $$$. Can any of these things be checked by myself rather then taking it to a shop. I can take it Precision Auto (chain auto shop) and they will diagnose it for $45, but thats $45 that I lose out on and wont go towards my repair so me trying to find the exact cause would be pretty beneficial. I also want to mention something I found strange. I rarely go out this early (6am pacific standard time) but today I had to run to the store for my wife before I go to work. Well I did not hear the sound even one time. Could it be the temperature? I even turned on the AC just so I can hear it and try to give a better explanation of the sounds and again, no sound.Does that make any sense or give any clue to what might be causing it?

[djkeev]

Quote, originally posted by jgarcia408 »Thanks for the reply. Well everything said makes me a little nervous, simply because with each item you mention I see $$$. Can any of these things be checked by myself rather then taking it to a shop. I can take it Precision Auto (chain auto shop) and they will diagnose it for $45, but thats $45 that I lose out on and wont go towards my repair so me trying to find the exact cause would be pretty beneficial. I also want to mention something I found strange. I rarely go out this early (6am pacific standard time) but today I had to run to the store for my wife before I go to work. Well I did not hear the sound even one time. Could it be the temperature? I even turned on the AC just so I can hear it and try to give a better explanation of the sounds and again, no sound.Does that make any sense or give any clue to what might be causing it?That screams Worn / Bad fan belt. They are easy to install with very few and very basic tools. Do you have a can of spray product? Carburetor cleaner, brake cleaner, belt dressing, etc?? Try to stay away from oils such as wd 40 and similar for they harm rubber.Carry the can with you, when the noise starts and can be heard at idle give the belt a shot and see if it quiets down.You might just buy a can of belt lube and give it a shot. It doesn't solve a worn belt problem but it will quiet it down for a period of time (usually a short period of time).Look carefully at the belt. There is a smooth side and a grooved side. The smooth side should be shiny but not cracked at all. The grooved side should be continuous ribs without any cracking or missing bits.It may also be the tensioner bearing as well or instead of but a fan belt is relatively cheap and an easy fix.Dave

[jgarcia408]

Thanks so much for the info. Im hoping that's the problem. I will have to check when I get home from work though. I will post here with my findings. Thanks again.

[jgarcia408]

Please excuse my ignorance, but I just cant figure something out. Im looking for information on fan belts for the 2004 Pontiac Vibe and everything on google keeps bringing me to Serpentine Belts. Are those the same thing?Also, sorry for using reply rather then edit. Im sending this from my cell and for some reason I couldnt send it in edit mode. Weird.

[djkeev]

Yes, the serpentine belt is one long continuous belt that operates, on some engines, all of the belt driven accessories. Some cars still have multiple belts, some a mixture of V belts and serpentine belts, some all serpentine type.Dave

[jgarcia408]

Great. thanks again. The information is greatly appreciated.

[gralm]

Is sound you are hearing metallic? It may be pinging. Seven years old car may have carbon buildup in its cylinders. For this problem (and it is problem for gas mileage and car's long term health) you can buy complete engine cleaner (Tectron or Slick 50) in any car part store or gas station for less than $10. The only inconsistency with my diagnosis is it gets louder in reverse driving.

[djkeev]

Quote, originally posted by gralm »Is sound you are hearing metallic? It may be pinging. Seven years old car may have carbon buildup in its cylinders. For this problem (and it is problem for gas mileage and car's long term health) you can buy complete engine cleaner (Tectron or Slick 50) in any car part store or gas station for less than $10. The only inconsistency with my diagnosis is it gets louder in reverse driving. Not saying it IS a belt but a belt slippage would be more pronounced in reverse because of the low gearing in reverse thus the engine spins faster when going backwards.Dave

[jgarcia408]

Well I checked the belt but just a visual check because I wasnt able to get any spray product before I came home from work today.But the belt feels pretty rough. The grooved side looks ok for the most part, but there are some cracks here and there. The "smooth" part is not very smooth or shiny. Its actually weird, half of the belt is smooth, but the other half is really rough. Is it suppose to be like that? When I say have, I dont mean in terms of length either, I mean half the width of the belt.I have tomorrow off work tomorrow so I hope to be able to get some of the spray and see if I can get the sound to stop.

[jgarcia408]

Hi guys, Im back. Im pretty sure the serpentine belt needs to be changed. Not pretty sure, positive. I did a check in better light today and there are plenty of cracks in it. Now I called around and the cheapest a repair place can do it for me locally is $89.99. I can get a belt for $18-$30 at a local auto parts store. What I want to know is, is this something you guys think I can do on my own? Although I am not a mechanical genius, I can do basics. I put the brakes on my vibe about 4 months ago and it went very smoothly. How hard is this compared to something like brake replacement? Ive been looking at guides and other posts around the web and it looks very easy, but I dont want to jump into this without some reassurance. Can anyone tell me how are this actually is or is it really as easy as it looks?

[djkeev]

It's amazingly easy, even a caveman can do it.I'll look around and see if there are any instructions already posted on here. Simply by using a wrench release a spring loaded tensioner pulley, slip off the old belt, slip on the new in the same path as the old (very important!!) and allow the tensioner pulley to once again tension the belt.

[jgarcia408]

Well, I went for it. I ended up just getting a lender serpentine belt took from Auto Zone and did it myself. I took me about a half hour because I couldnt get the belt positioned properly. I ended up taking out the belt and tried another way of connecting the belt and within 10 minutes I had it on. It was very easy and I saved myself roughly $70. As for the sound, my car is running much quieter now. When I reverse and when I turn on the AC the car pretty much sounds the same as if I were just driving normally. Idling even sounds a little quieter. One thing that took my by surprise is that my AC seems to be cooler now. Does that make sense?Anyways, everything is working great. I want to thank you again for your help and recommendations in terms of it being the belt.

[jkm311]

Your belt is running through all those accessories much easier, more efficiently and tighter now. It is quite possible that everything is much improved, just with this belt change. Good work.

[djkeev]

Good For you!! Glad it was "easy" for you, glad it fixed your noise. When the belt is old and dry and stretched, it doesn't grip the pulleys as well hence slippage. That slippage was most likely the noise you were hearing.Dave

[jgarcia408]

Quote, originally posted by jkm311 »Your belt is running through all those accessories much easier, more efficiently and tighter now. It is quite possible that everything is much improved, just with this belt change. Good work. Nice, I didnt know that it would improve other things also. Just an added benefit. After doing this and feeling the satisfaction of doing it myself I have actually started thinking maybe I should go back to school for this type of thing. Hmmm, just a thought.