Please help end my Mercury Misery: '05 Sable driving me nuts.

I've been helping an elderly friend with a very annoying problem with her 2005 Sable with a 3.0 ohv V6, a "Vulcan" engine, I believe. About 150k miles, ridden hard and put away wet.

It has a terrible belt squeal. Her son replaced the belt, and it didn't help. Then he applied belt dressing spray, and it got worse, and made a huge mess in the engine compartment.

To my ears the squeal sounds like it's coming from dead center of the belt drive area. I found both the idler and tensioner pulleys worn and wobbling, so I replaced them both. No change.

Next she asked me to change the PS pump. I didn't think it was the problem, but since the plastic pulley had an obvious crack in it, I agreed that it needed to go anyway. What a miserable job that was for no change to the squealing.

I thought for sure it was the water pump, I changed it, and I'm glad I did because the impeller was contacting the back of the housing, but the stupid squeal came right back!

I had the wheel liner out while I was working on the WP, and noticed the squeal was much louder in the wheel well. The crank pulley and harmonic balancer are in the wheel well.

My new hypothesis is that the harmonic balancer is failing and rubbing or vibrating on the pulley, in fact, I think the belt dressing applied by her son attacked the rubber, and that's why it got worse after it was applied, but it may have been on its way out anyway.

Is balancer failure common on these engines? Is there something else that I could be missing? I've never seen a balancer failure on an engine that wasn't nearly as old as me before.

My 3.0 Vulcan ate belt tensioners. Check that. I'll belt your "new part I still garbage.

Belt dressing should be banned.

I would start eyeballing the pulley alignment really closely and make sure none of the pulleys are suspiciously shinier on one side than the other (of where the belt rides).

Make sure the belt is routed correctly. Sometimes cam position sensors can squeal just like a belt.

Just for fun I Googled "3.0 Vulcan squeal" and it would appear that you are not alone (to put it mildly.) Several of the top search results include videos with sound, if you want a multimedia diagnosis. Cam position sensors come up a lot; OTOH, one guy says he fixed his squeal by changing the brand of belt he was using. The truth is out there!

I'm not sure if the 3.0 Vulcan is set up the same way, but on a 3.8 in a Mustang, I ran into a belt squeal I could not find or get rid of. So I got out my trusty stethoscope and found that the squeal was coming from the cam position sensor drive. It basically goes where the distributor was once located before they went to a DIS system. It looks like half a distributor with a drive gear on the end that engages with the cam with a little hall effect sensor on top. You mentioned that it has been ridden hard and put away wet, so my guess would be that oil sludge is packed up in there, causing your squeal. You may be able to disassemble, clean and re-install it. Just make sure it spins freely before you do. If none of that applies, then I would get out the stethoscope, or even a piece of tube, anything to transmit noise to your ear, and start searching. Just watch out for the belt and pulleys!

I hadn't considered the cam sensor. If it is, would the noise be generated in the top section, or down in the distributor shaft looking section?

I think what I'll try next is to take the fender liner back out, remove the belt and run for a minute. If it's the balancer or cam sensor it should still be noisy. If it still sounds like the balancer ringing on the pulley, I'll remove the pulley and try again. There would likely be unusual wear on the backside of the crank pulley too.

Edit: cam sensor is on the opposite side of the engine as the noise. I doubt that's it.

A little bit of googling indicates that Explorers with v6s have harmonic balancer failure that sounds like a belt squeal.

Uh, i'm pretty sure the harmonic balancer failing CAUSES belt squeal unless someone can explain to you exactly what is moving on a harmonic balancer that has nothing to do with a belt and causes that noise.

A bad harmonic balancer (outer ring came unglued) is usually pretty easy to see. Set it at TDC with a plastic rod down the #1 plug hole, see if the timing marks are lined up. I guess you could alternatively put a line on it a grease pencil and drive it around a while.

In reply to BrokenYugo and Vigo:

In this case the outer ring of the balancer is flush with the backside of the crank pulley, IDK if it has timing marks, but the toothed EDIS wheel for the crank position sensor is on the inner section and up against the timing case. I tried pulling and pushing on the crank pulley, but I think it's actually fastened to the inner section.

I think the rubber is bad and allowing the outer ring to contact and vibrate on the backside of the pulley. The sound is just as much a metallic ringing as it is a squeal. Some of the failed exploder balancers were described as ringing or chirping, and were not completely separated.

I'll get back to this Monday or Tuesday afternoon and remove the pulley. If the balancer checks out OK, I'll be all out of ideas.

A mechanics stethoscope can be your friend,

Harbor Freight

I think you're on the right track. I had one of those go bad in an Escort when I idled it for a while with the A/C on.

something easy to try just to rule out other parts is start it without the belt on it just to be positive that is so something on the belt drive.

i would also be suspect of the balancer, I have seen them before where, with the engine off, the belt could me moved ~1 inch back and forth from the slack in the broken down rubber in the balancer

Fueled by Caffeine wrote: My 3.0 Vulcan ate belt tensioners. Check that. I'll belt your "new part I still garbage.

Winner Winner chicken dinner!

The tensioner felt strong, but when I removed it, it was clearly worn out.

A new tensioner, new belt and cleaning every last bit of belt dressing gunk out of every Vally of every pulley did the job.