On cold start days i hear a low harmonic whistle sound that matches the engine speed with shifts. I assume its probably the belt worn? or could it be the tensioner? Just wondering if anyone has had a similar issue that knew which one of those was the problem since the tensioners are pretty dang pricey and not super sure how to test the spring load. If i have to i can take the idler and tensioner pulleys off to try to check for bearing wear but thats not high on my to do list at the moment and hoping i can save some time if someone already knew.
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harmonic deep whistle sound
- Thread starter Crankor
- Start date
It's hard to tell without hearing it but it could be a number of things:
- Belt
- Pulley bearings
- Alternator bearings
- Power steering pump
- Low power steering pump fluid level
If you have an automotive stethoscope you can locate where the sound is coming from. The one I use that works pretty well as it gives you an option to hear mechanical and air induced sounds.
Ideally you would do this with someone slowly revving the engine while the other listen for where the sound is coming from.
You can check the belt tension by hand. Find a spot on the belt in between two pulleys and twist it until the belt is 90 degrees from where it was. Obviously if you use a lot of force you can make the belt twist more than 90 degrees but the idea is to use medium force. If you can get it to 90 degrees with medium force the belt tensioner is fine. If you can do more then it's possible the tensioner or belt need replacing.
Belts don't stretch that much as they have cords inside. Belts crack where the V grooves are. If you see cracks on the belt where the belt bends backwards, I'd recommend swapping the belt. That's a very easy job. I've swapped my belt once already.
I've been on my original belt tensioner and I have 150K miles. I've swapped the bearings in all the pulleys. If you're up for swapping the bearings, then you'll be able to save some money there. There's a post on this here 3.5L - idler bearings
I do have a new belt tensioner and did a torque comparison and found no discernible difference. The belt tensioner has a 1/2" square slot for a wrench but testing it with a breaker bar or torque wrench may give you a false positive. This is due to the angle of how a breaker bar puts tension on the tensioner. You'd have to test it by pulling on the pulley itself. Also the bolt holding the pulley on the tensioner is threaded opposite. But the bolt holding the entire tensioner pulley is threaded as usual. The rest of the pulleys are threaded as usual as well.
Alternator bearings do get noisier as the alternator ages. If it's OEM the bearings should outlive the brushes. If it's aftermarket then chances are the bearings are going to fail sooner than later. You can use the stethoscope to hear the bearings.
Power steering pump does make noise. As it ages and the tolerances increase, the pump gets noisier. Check to see if you have enough power steering fluid. If there's just a tad less than ideal it could create a sound but I feel that's not the case here.
I know this might not be the answer you're looking for but hopefully this gives you some insight and direction.
- Belt
- Pulley bearings
- Alternator bearings
- Power steering pump
- Low power steering pump fluid level
If you have an automotive stethoscope you can locate where the sound is coming from. The one I use that works pretty well as it gives you an option to hear mechanical and air induced sounds.
Ideally you would do this with someone slowly revving the engine while the other listen for where the sound is coming from.
You can check the belt tension by hand. Find a spot on the belt in between two pulleys and twist it until the belt is 90 degrees from where it was. Obviously if you use a lot of force you can make the belt twist more than 90 degrees but the idea is to use medium force. If you can get it to 90 degrees with medium force the belt tensioner is fine. If you can do more then it's possible the tensioner or belt need replacing.
Belts don't stretch that much as they have cords inside. Belts crack where the V grooves are. If you see cracks on the belt where the belt bends backwards, I'd recommend swapping the belt. That's a very easy job. I've swapped my belt once already.
I've been on my original belt tensioner and I have 150K miles. I've swapped the bearings in all the pulleys. If you're up for swapping the bearings, then you'll be able to save some money there. There's a post on this here 3.5L - idler bearings
I do have a new belt tensioner and did a torque comparison and found no discernible difference. The belt tensioner has a 1/2" square slot for a wrench but testing it with a breaker bar or torque wrench may give you a false positive. This is due to the angle of how a breaker bar puts tension on the tensioner. You'd have to test it by pulling on the pulley itself. Also the bolt holding the pulley on the tensioner is threaded opposite. But the bolt holding the entire tensioner pulley is threaded as usual. The rest of the pulleys are threaded as usual as well.
Alternator bearings do get noisier as the alternator ages. If it's OEM the bearings should outlive the brushes. If it's aftermarket then chances are the bearings are going to fail sooner than later. You can use the stethoscope to hear the bearings.
Power steering pump does make noise. As it ages and the tolerances increase, the pump gets noisier. Check to see if you have enough power steering fluid. If there's just a tad less than ideal it could create a sound but I feel that's not the case here.
I know this might not be the answer you're looking for but hopefully this gives you some insight and direction.
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