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My name’s Benjamin, and someday I hope to be a certified mechanic.
That should sound simple enough, but there’s one additional complex: my car is a 2007 Mustang. She’s beautiful, but it’s my responsibility to take care of her now, and sometimes I know what I’m doing, sometimes I don’t. So, here I am, hoping to learn what I can.
I’m quoting my intro thread here for one reason: As I describe my problems, I may sound like I know what I’m talking about, and then immediately sound like a complete moron. It just depends on what I happen to have experience working with so far, so bear with me. If you feel that I might be misusing a term or talking about the wrong thing, please ask for clarification.
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I have a 2007 Ford Mustang 4.0L V6, 5s manual transmission, 71k miles. Yesterday while sitting in idle, I noticed a chirp/squeal coming from the engine. This is the first start up for the day, and the weather was particularly cold (some frost on the lawn, but no frost on the car.)
I decided to drive around for a lil bit to see how the sound would change. I drove around my residential blocks going between 10-30 MPH between 1st and 3rd gears. The sound did not change in pitch, but it did change in frequency. I took it out on the road for up to 55 MPH at 5th gear, and the sound would alternate its frequency based on my gear/speed. The faster I go in gear, the faster the noise repeats its frequency (pitch and volume appeared to remain constant, but I may be mistaken.)
Coming back home with the engine warmed up, the sound began to intermittently disappear. I decided another few minutes of driving might reveal something, and the sound would continue to return and disappear. It seemed that the warmer the engine became, the quieter/less frequent the sound also became.
I think I easily narrowed down the noise to the belt and pulleys, and I thought that this could be a misalignment in the pulleys or an issue with the belt tension. Before testing, I let the engine cool down so I could be certain the noise would return. After several hours, I start the engine and the noise does in fact return to its original volume.
To test the issue, I took a small spray bottle filled with water and jetted the inside ribbing of the belt. The sound immediately disappeared before returning about ten seconds later. At this point, I was confident the issue was with the pulley alignment, rather than the belt tension. This should also mean that the noise coming from the engine is technically a “chirp” and not a “squeal”, although I’m not so sure about the jargon.
This is where I get stuck in my diagnosis: I fully expected to find one of my pulleys to wiggle too much during operation, but they all look steady as can be. The only thing I can think of is that the idler pulley has a thin streak of wear on it, and it shakes ever so slightly while the motor is running, almost barely visible.
Here are some questions:
1) Did I properly test and diagnose my chirping noise up to this point?
2) What else can I do to narrow down the issue further?
3) …Is it indeed a “chirp” and not a “squeal”? :S
4) Could this sound also be caused by a faulty camshaft position sensor, or did I eliminate that possibility with the water test?
5) Should I go ahead and try replacing the idler pulley, or have I yet to narrow the issue down enough?I have a camcorder, so I’m capable of taking any pictures, video, and sound recordings anyone may need to help me learn how to find and fix the issue.
Thanks,
Ben
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You may just need a new belt. see if this helps further.
http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car?start=3#OtherEngineCompartmentNoises
Engines with spring loaded tensioners, which is what I think yours has, rarely make belt noise. If a new belt doesn’t do it and all the accessories spin freely without making bearing noise (check when replacing the belt) then the tensioner may need replacement.
No, you need either mechanic sthetoscope or simple length of garden hose or even stick against your ear – I use thumb to ear to stick – do pin point the chirp.
Here’s my prediction for you:
#1 – idler bearing
#2 – water pump bearing
#3 – alternator bearing.
#4 – all of the above, as it’s Ford.Just an update: I spend quite a bit of time at work, so it takes me a while to have the time to get to these things.
I just discovered some fraying on the side of the belt, so tomorrow morning I’m going to buy a new one. When I do that, I’ll check all the pulleys closer, especially the idler. I’ll let you all know what I find. I’ll also try to take a couple pictures of the belt and idler to show what I found.
EDIT: I had another thought. Could it be the harmonic balancer needing replacement? How do I find out?
Fraying on the side, huh? You want me to tell you or you want to guess yourself, WHY it frayed?
I’ll be nice. One of the pulleys center bolt is set crooked, or one of them bearings is failing, resulting in belt NOT running plumb in pulley grove(-s, not sure if you have a V-belt or multiribbed). This results in one edge wear. Chirp is NOT coming from a belt. Don’t even try that. Belts squeal, they don’t chirp.
I had 99 Silverado with chirping idler.Had to replace them twice,in 3 yrs, as it was not set plumb in the engine head. It’s quality issue, buddy.
And the other side to this issue is, it makes belt run crooked, THAT adding unnecessary torque and wear onto the rest of the parts belt is propelling.So, I might be an idiot.
I had to wait for an opportunity to rent a breaker bar from autozone, but when I finally got the belt off, I found streaks of orange along the ribs in a couple sections that I hadn’t seen before. Apparently, this is the nylon underneath the rubber, and the belt had worn through. I’d suspect that this is the same belt the car has had for all 71k miles, and if so it may also explain the minor fraying along a part of the edge. Normal wear.
I put a new belt in and she’s purring. If the sound returns, I’ll return to look at those pulleys, but for now I’m only considering replacing the idler because of the thin streak of silver it has. Tensioner seems just fine, and all the other pulleys checked out while I had the belt off. I haven’t checked for alignment yet, mostly because I’ve run out of time for today, but I’ll see about trying to rent a laser tool on my next day off.
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