Constant road noise over 50 MPH

[bfretless]

Anyone want to help me figure out where my noise is coming from? Are 2001 PTs generally noisy at highway speeds? I haven't seen many complaints on the forum, so I'm thinking mine may have a problem.

Up to about 45 or 50 mph, everything's cool with my Cruiser. Above that, a noise starts to build in the back, just kind of a general roar. It's loud enough you definitely have to raise your voice to have a conversation on the highway. At first I though it was tire noise, but it stays the same no matter what surface I'm on - asphalt, new concrete, grooved - doesn't matter. I have also gotten up to speed and thrown it in neutral. With the engine idling the noise is still there and loud, and coming from the back of the car.

So I'm thinking it's the rolling hardware - most likely wheel bearings. Got it up on stands and checked both left and right for play, they seemed good to me at both 12 & 6 o'clock and 9 & 3. With a good hand spin they freewheel pretty OK, there's a little noise but it's hard to describe. Should they be silent?

Brake calipers seem good. If the brakes were dragging I'd have other problems, right?

I'm tempted to just replace the hub assemblies and hope for the best, but I hate throwing parts at a problem before I'm sure what it is.

So give me your ideas, wisdom gained from painful experience, wild guesses, whatever you got, and I'll let you know how it turns out. Thanks!

[VanillaVert]

I've never really noticed road noise before on our PT Vert other than the wind sneaking in at the front of the window seals once in a while.

Today though, we took about an hour trip to pick up some artwork and there was nothing good on the radio and I just shut it off. So, settled in for the other half of the drive and noticed that I could really hear the concrete portions of the highway almost singing. Typical for any car but this seemed different somehow. It was mostly above 60mph... On the macadam, not so bad but on the concrete it was really noticeable.

To describe the sound is a tough one. Closest things I can think of is to describe it as a bum syncro in a manual trans (We have an Auto), or... If you were ever in an old muscle car with really tall gears in the rear on the street.

I'm replying because I was thinking wheel bearings too, seemed to me like it was that kind of sound.

I'm interested if this is a common thing as well. I know every car is different and something as simple as tire brand can cause this. I don't notice any alignment issues and all the bushings seem tight (only have 36k on it). I do think the one motor mount is getting due for a swap but that's about it.

Look forward to hearing other's experiences!

[Busted_PT]

I just replaced a couple bearings. One on each end. They were bad when I got it. You had to get it to over thirty then you could really hear it. Turning the wheel helped as long as it was in the right ddirection.

[bfretless]

I'm pretty sure this isn't tire noise, but I'll rotate the tires just to be sure. I've got different brands front and back, so rotating should change something, I'd think, if it is the tires. I'll also relube the caliper slide pins in case the brakes are sticking.

If that doesn't help, I'll throw on new hubs/bearings.

[Busted_PT]

Should be able to feel the rough bearing in the rear when turning the hub. It should be real smooth.

[05vanilla]

Just yesterday I started hearing that familiar growling sound. I'm pretty sure it is the right front bearing, gone at 86k miles. I recall having to get the left front replaced under warranty, somewhere around 30k. As always, there are great instructions to be found on these forums, so I may be taking on this job myself (with the help of a machine shop to handle the pressing). Maybe I should replace both sides at the same time...

There is probably not an easy answer to this question, but here goes: does that growling sound indicate a failure is imminent? Or do I probably have time (another week or two) to keep driving my PT while I'm waiting for parts?

[NitroPT]

Many noises can not be duplicated be raising the chassis and rotating the drive train or moving the suspension. You can however use Audio hearing devices to track down the low volume sounds that may be increases with chassis load and vehicle speed?

Use one of these.

[NitroPT]

Originally Posted by 05vanilla

..........................
There is probably not an easy answer to this question, but here goes: does that growling sound indicate a failure is imminent? Or do I probably have time (another week or two) to keep driving my PT while I'm waiting for parts?

If you don't know what the noise is..DON'T DRIVE THE VEHICLE until you at least know what is causing the noise! You may not only effect the safety of your self and the condition of your PT but also the safety of those of us driving near you if something were to fail causing an accident!

It is kind of like when you come up to a stop light at a busy intersection and you hear the guy in the POS next to you applying his brakes and the scarping sound of the brake pads metal to disc wondering why this guy does not fix the "BRAKES" so he can at least stop safely!??

[Busted_PT]

If you turn the wheels to on side or the other and the noise comes or goes. It's the bearing. This can go on for many miles without failing or being dangerous. So if you know it's the bearing then get the stuff coming and do it. Check the ground straps to the struts. If broken, it's supposed to shorten the life of the bearings.

[05vanilla]

I'm pretty sure it's the right-side bearing. If I turn to the right the sound goes away, and it sounds exactly like it did when the PT had a bad front bearing several years ago.

Good tip on the ground straps - I've been reading the threads on that and will check them.