97OutbackTN

Well, I replaced the filter and checked the cover. It seems to have improved a bit, but it's still there. What it sounds like is it occurs when the RPMs are over 3000 in 4th gear and the engine is working hard (like going up an incline). I know for sure it doesn't make this noise and feel when I'm simply revving the engine in Neutral. It also doesn't do it when I'm accellerating. I have not done the catalytic converter test as listed above, but will when I get a chance. However, I'm willing to bet it comes back negative just because of the fact it doesn't make the sound during accelleration.

I'm going to check (and replace) the air filter...now how do I get that housing off? I unlatched the clips, but couldn't get the thing to pull off.

In looking at the service record, I can find very little that looks like it might be related. The ones that pop up are - replace fuel filter - replace air filter - replace pcv valve - drain and refill coolant - install air control valve (this might be the same as PVC) I do know that I bought the car with 79k on it, so I don't have a record of service prior to this. I have no idea what service was done up to that point.

I feel like I'm working with a bunch of doctors who are trying to understand a problem I'm having and offer possible causes. I've replaced the air filter before and it's had no effect. My current air filter needs to be replaced though so I'll try that and check the box while I'm at it. I'll give the catalytic converter test a shot as well. I haven't really noticed the problem during regular accelleration, but of course I'm only above 3000rpm for a few seconds. The noise itself, along with the vibration, seems to be coming from the front of the car...either engine area or underneath the front row of seating. As far as the car's history, it seems to be fairly normal. There is a knocking noise that occurs when the car is idling, sounds sort of like a piston slap (I think), but my mechanic said it's common on these cars as they get older and is not a problem.

I know the description is vague...sorry! I wish I could do a better job, it's just a really difficult sound to explain. It's sort of like this: imagine you're inside of a room, and on the other side of the wall in the next room somebody is running a commercial-sized air compressor. If you imagine what this sounds like through a wall, it's a low-frequency hum with a vibration you can feel if you put your hand on the wall. That's what my car sounds and feels like around 70mph. The premium grade I've been using for a few years now because the car started making mild pinging noises, and I haven't had a problem with those since. Fuel economy has been the same. The problem seems to get better as I approach 80 and above. This problem initially showed up after a 90,000 mile service by a Subaru dealer a couple of years ago. It's never been a huge issue, but one that has been bothersome simply because nobody seems to be able to figure the cause out.

First time post under this name (forgot the password to my last account and had deleted the corresponding email address). I've got a 97 Outback with 123k on it. The car rides very well, but it's developed this problem at highway speeds. Usually above 65mph, there is a loud low-frequency engine vibration. It's hard to describe, but it's as if the fuel line has buildup in it so it's having to try harder to pull fuel through. Once I reach my desired speed (say 75mph) and move to hold it instead of accellerating, the sound gradually subsides, but as soon as I try to speed up, it's immediately back. There's also a bit of power loss as well. I know it's an engine problem because the car rides fine and handling is smooth. It's not the same kind of vibration anyway. It's almost as if someone has left a bass guitar on the same low note with the amp turned up. You can feel it resonating and hear it. My mechanic has said it could be a wide variety of things and it's probably not too serious so not to worry about it. It's just bothersome to me. Any thoughts would be helpful. Thanks! BTW, the car is an automatic and I use premium fuel in it.