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Car Geeks - Does this look right?
Posted by: graylocks
Date: May 13, 2012 11:59AM
my 2004 Dodge Caravan has been making an increasingly worrisome noise. to these untrained ears it sounds like a belt problem. i opened the hood today and saw this:



not that i've paid much attention but i've never noticed that shiny roller before. is the belt supposed to be on top of that rather than under it?



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Car Geeks - Does this look right?
Posted by: davester
Date: May 13, 2012 12:12PM
Not necessarily.



"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan
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Re: Car Geeks - Does this look right?
Posted by: btfc
Date: May 13, 2012 12:22PM
Use a piece of garden hose or a paper towel cardboard tube as a stethoscope to identify exactly where the noise originates. Be careful around the fan.
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Re: Car Geeks - Does this look right?
Posted by: JoeH
Date: May 13, 2012 12:39PM
If the belt is taut, then it is on the right side of that idler pulley. If you have belt slipping sounds, then it could be nearly worn out or a tensioner needs to be replaced or adjusted. Belt life for a serpentine belt is about 100,000 miles. You may also have a v-belt that drives a power steering pump or other auxiliary device, those can wear out sooner and squeal.



Edited 1 time(s). Last edit at 05/13/2012 12:40PM by JoeH.
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Re: Car Geeks - Does this look right?
Posted by: graylocks
Date: May 13, 2012 12:54PM
Quote
JoeH
If the belt is taut, then it is on the right side of that idler pulley. If you have belt slipping sounds, then it could be nearly worn out or a tensioner needs to be replaced or adjusted. Belt life for a serpentine belt is about 100,000 miles. You may also have a v-belt that drives a power steering pump or other auxiliary device, those can wear out sooner and squeal.

hmmm. that belt is taunt. the intermittent noise i was hearing inside the car while driving i'd describe more as a rumble/rattle. when i opened the hood this afternoon there was a whiney squeal.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama



Edited 1 time(s). Last edit at 05/13/2012 12:54PM by graylocks.
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Re: Car Geeks - Does this look right?
Posted by: dad@home
Date: May 13, 2012 01:10PM
That is an idler pulley. I can't tell if is the tensioner for the belt from your photograph so there may be another idler as well. The working side of the serpentine belt has the multiple grooves and the idler which presses on the "non-working" or smooth side of the belt is supposed to be smooth and shinny.

Belt noise can be from slipping belt (much less likely with a serpentine belt vs. V-belt)
but much more likely is coming from a bearing. Potential bearings include idler pulleys, AC compressor, water pump or alternator.

good luck

dad
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Re: Car Geeks - Does this look right?
Posted by: Bernie
Date: May 13, 2012 01:16PM
If the belt was never overtightened:
The Compressor will loose it's seals and freon before a bearing goes bad.
The Alternator will not charge before a bearing goes bad.
A water pun is all mechanical and will make noise before locking up totally and burning up the belt.

That is my rant and I am sticking to it.




Staunton, Virginia
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Re: Car Geeks - Does this look right?
Posted by: graylocks
Date: May 13, 2012 01:19PM
Quote
Bernie
If the belt was never overtightened:
The Compressor will loose it's seals and freon before a bearing goes bad.
The Alternator will not charge before a bearing goes bad.
A water pun is all mechanical and will make noise before locking up totally and burning up the belt.

That is my rant and I am sticking to it.

the AC has not been working well though it wasn't a winter priority. number 2 is seeming likely since charging has not been an issue.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Car Geeks - Does this look right?
Posted by: lost in space
Date: May 13, 2012 01:29PM
Quote
dad@home
That is an idler pulley. I can't tell if is the tensioner for the belt from your photograph so there may be another idler as well. The working side of the serpentine belt has the multiple grooves and the idler which presses on the "non-working" or smooth side of the belt is supposed to be smooth and shinny.

Belt noise can be from slipping belt (much less likely with a serpentine belt vs. V-belt)
but much more likely is coming from a bearing. Potential bearings include idler pulleys, AC compressor, water pump or alternator.

good luck

dad

Power steering pumps too.
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Re: Car Geeks - Does this look right?
Posted by: tenders
Date: May 13, 2012 01:51PM
I believe there is a diagram of how the belt is supposed to be routed under the hood, to the right or left of the hood release mechanism - near where you might put your hands while leaning over the engine wondering WTF is wrong with it. If it isn't there it might be on the wheel well near the belt itself.

I think those belts are automatically tensioned, and the tensioning pulley springs up easily with a socket wrench, allowing the belt to be easily removed and replaced with no other tools.

For $20 a new belt will rule out belt problems altogether. The shininess you're seeing on the pulley is normal.
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Re: Car Geeks - Does this look right?
Posted by: Racer X
Date: May 13, 2012 06:37PM
Quote
JoeH
If the belt is taut, then it is on the right side of that idler pulley. If you have belt slipping sounds, then it could be nearly worn out or a tensioner needs to be replaced or adjusted. Belt life for a serpentine belt is about 100,000 miles. You may also have a v-belt that drives a power steering pump or other auxiliary device, those can wear out sooner and squeal.

serpentine belt life is 30-40K, not 100K. Unless you have some sort of high tech spectra fiber/synthetic rubber belt.

Spring-loaded tension may have lost its tension, or its bearing may be going bad. Anything wobbling or rumbling as you watch the belt while the engine is running?
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Re: Car Geeks - Does this look right?
Posted by: JoeH
Date: May 13, 2012 09:05PM
Quote
Racer X
serpentine belt life is 30-40K, not 100K. Unless you have some sort of high tech spectra fiber/synthetic rubber belt.

Last three cars I have owned have had a replacement schedule for the serpentine belt of 100K, 30-40K is about normal for a regular V-belt. The only time I have replaced serpentine belts earlier than that has been when changing a timing belt at the same time. No need for any "high tech" material, this kind of life for a serpentine belt has been standard since at least the '80's. People have had them go for over 150K.

P.S. My son's 2001 Buick has the first scheduled inspection of the serpentine belt listed at 60K. Not replacement, and it is listed as part of the emissions group.
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Re: Car Geeks - Does this look right?
Posted by: wowzer
Date: May 13, 2012 09:20PM
I thought belts also had to be replaced at a set schedule as well....



All I ever really needed to know, I learned from watching Star Trek.
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Re: Car Geeks - Does this look right?
Posted by: JoeH
Date: May 13, 2012 10:20PM
Quote
wowzer
I thought belts also had to be replaced at a set schedule as well....

Yes, they should be listed in the Owner's Manual for the vehicle. A common one I have seen for serpentine belts is inspect at 60K, replace if needed. Then reinspect every 30K afterwards. Standard V-belts are to be inspected at 30-40K, and then every 15-20K afterwards on schedules I have seen. Some schedules include a length in time as well as mileage as belts do age just from passage of time. They may add a final recommended replacement mileage as well if not replaced earlier when inspected, my last car listed 105K as that was also the point to change the timing belt.
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Re: Car Geeks - Does this look right?
Posted by: iamrfixit
Date: May 14, 2012 09:37AM
Smooth pulleys almost always run against the back side of the belt, the ribbed pulleys run against the ribbed side of the belt.

The spring loaded belt tensioner on many caravans had some tendency to fail by sticking into position and not allowing the tensioner to move freely and take up slack as the belt wears. My wife's 97 was stuck in under 50k miles. This can allow the belt to run loose, slip, or wear prematurely. It seems to be a fairly common problem in these vehicles.

Of course there are many other things that can go wrong with the belt driven components and cause noise; such as idler or tensioner pulley bearings, PS pump, water pump, AC compressor idler pulley bearings, or alternator among the most common problems. An improperly tensioned belt can cause or contribute to many of these problems.

I have seen many OEM quality belts last well over 100k, I just changed the factory belt on my 10 year old, 105k mile E150 van and it still looked very good and likely would have lasted many more miles. It is fairly tough to gain access to and difficult to see well enough to inspect it thoroughly without removing it. With the kids using the van for a 6 hour trip I felt more comfortable with a new one in place.

I usually just inspect the belt at every oil change for signs of cracking, missing chunks of the ribs or fraying of the edges. When these problems begin to appear it is time to change it.
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