Another weird noise thread

[mayorcool]

I've searched around the Pilot forums and other Honda websites for a noise similar to this to no avail, so please forgive me if it's a repeat

So on a 2005 Pilot, at speeds of 25-45 while going in a straight line, and while lightly feathering the accelerator to maintain speed I will get a grinding/almost like a quiet jackhammer noise from somewhere in the engine. The first time I heard it I actually thought I was passing by someone jack hammering. The noise will last 2-4 seconds or if I depress the accelerator more or let off it will stop (although sometimes letting off it won't stop right away...but it does seem to make it stop faster). Sometimes the noise happens frequently, sometimes it won't happen for an hour. I've been unable to investigate further simply because of how difficult it is to reproduce the noise.

Any ideas?

Edit Update: The shop found one bad motor mount. The mechanic said something about the vibration affects the exhaust at some point and he was 75% sure this would fix the noise. It was fine for awhile after leaving the shop. I drove around an industrial park at 30mph for 20 minutes with no problems, then headed home. Almost to my house, the noise occurred...but just for a split second...barely enough for me to question if I actually heard it or not. Guess I'll keep listening.

[mayorcool]

Well, the noise is still there after the replaced motor mount.

It's such a strange vibration noise, I can't really figure it out and it's difficult to reproduce I'm not sure how to even describe it to a mechanic.

[2010exl]

It is common for the heat shields on the catalytic convertor to rust and break away from one of the mounts. At certain engine speeds it vibrates and you can hear it while driving.

The front convertor is the most likely culprit. The last couple that I repaired rattled at about 2200 rpm.

[mayorcool]

This seems to happen more frequently at 32mph and 1500rpm. I've had it happen at 40mph and 2000rpm. I climbed under and felt/looked for any loose heatshields, but I'm no mechanic...everything seems secure.

The thing is, I really don't have the money to keep paying a mechanic to chase a phantom vibration around... especially if it's just a rattly heatshield or something...but on the other hand I don't want to ignore a problem that may get worse or create some other expensive problem.

[3rdrow]

maybe there are more than 1 motor mounts bad? it seems like if they replaced one and it stopped/reduced the problem just for a short time, then the new motor mount helped the problem while not solving it alotgether. now that you know it is still doing it, is it any better than before the 1st motor mount was replaced?

[2010exl]

Try this....

On a quiet side street with he engine warmed up, shift the transmission down into "1" and slowly accelerate up to about 3500 rpm.

If it is the heat shield rattling, you should be able to consistantly reproduce the rattle somewhere in that rev range.

If not, you may have something else causing the noise.

Again...the most common culprit for me is the heat shield on the front catalytic convertor between the convertor and the engine. It is difficult to see, and not possible to remove without removing the convertor

[mayorcool]

The mechanic agreed with the heat shield idea. Apparently, they usually weld the heat shields to repair them, but the mechanic said these were too badly damaged to repair. We decided to just take upper and lower shields off to see if the noise would occur. Well, as soon as we got the Pilot close to home the noise started again and we're back to square one.

The noise is definitively at 1500 rpm low 30 mph noise...anything over 2 and it's gone, and it seems to be more frequent on a warm engine. I'm wondering if it's something to do with the exhaust.

Thanks for the help, I'll keep updating as the saga continues.

[mayorcool]

Well, in the last 3 days the Pilot went from my local mechanic to the Honda dealer. I've had two different technicians ride with me while I demonstrate the noise. Both have stated that they have never heard anything quite like it. Apparently it sounds like a bad air pump, but the Pilot does not have an air pump. They've poked and prodded and checked everything and today concluded that the transmission is definitely in need of replacement.
Tomorrow I will have owned the vehicle for two weeks.
I'm wondering if the previous owner knew about it and thought he'd trade it in to save himself the thousands of dollars. =/

[PghPilotOwner]

I have the same issue. I have a 2005 Pilot EX-L wth ~180K miles. For ~6-8 months now, my car makes a noise that sounds like jackhammering or jake brakes or rumble strips....don't know quite how to describe it. Sounds most like jackhammering.

It occurs randomly, is NON reproducible, happens at both highway speeds and small town speeds, usually while foot is on accelerator but doesn't change when foot it taken off, and only lasts 1-3 seconds. At first it only happened once or twice every month or so and now happens once or twice every week or so.

Like the other poster, don't want to pay money to chase a phantom sound and it's difficult to have it looked at when it happens so infrequently and randomly. I'll keep an eye out here to see if anyone finds a fix.

[harley909]

I had a rock ( a small piece of gravel) stuck in the heatsheild on the muffler one time that sounded like that. It took a lot of fooling around to get it out.
It made one hell of a racket, grinding noise.

[1YESfan]

Goodness, whether the noise had anything to do with a single "bad" motor mount I can't understand why you didn't have or the mechanic would not offer ( other than possible return buisness and money) to replace all the motor mounts while he was there.

[mayorcool]

I've had the Pilot back with the new (rebuilt) transmission and the noise is definitely gone. The dealership ended up paying for it since we only had it for a couple of weeks.