I bought my 04 HCH in August of 07. Used, it had 126K miles on it. I have averaged around 40 mpg in this car - which is better than any car I've had before. I drive a lot of short-distance (<30 miles) highway. I live in the country, so not much in-town.

Anyway - I got my Catalytic Converter replaced about a week ago. After driving on dirt roads when I had to take my aunt to the doctor, it started making this grumbling noise. It does it mostly when I'm going under 40 mph and you can only hear it on the inside. I've started the car and heard it inside, gotten out and not been able to hear it. After having the converter replaced, it still does it.

Ideas? Suggestions?

Another thing - when I put it into reverse, it kind of stalls a little bit before it will actually move. I have read in some places that this could be the oxygen sensors, but the dealer tells me that if the sensors were failing, the check engine light would be on and it hasn't been on at all since I got the converter replaced.

I'm taking it in Monday morning for them to look it over again but if you guys have any ideas about what it might be, I'd love to hear them.

 

What state do you live in; is the weather really cold? My car seems to be more noisy when it's really cold, and it seems like the shift into reverse is a bit slower in very cold weather. Once it's warmed up, the response is better when shifting to reverse.

Since your car has a lot of miles on it, and if you've been driving on dirt roads a lot, your cabin filters might be very dirty. Not sure if dirty filters could account for any noise, but they might make it harder for your AC/fan/heater/defroster to work. The cabin filters might not have been changed by the previous owner. They are located behind the glove compartment. The dealerships can change the filters for you, but it's a pretty easy do-it-yourself job if you're up to it. There are some threads here about it, if you do a search on "cabin filter".

Here's a link to one thread:

https://www.greenhybrid.com/discuss/...ections-12895/

The only other thing I can think of that would cause a grumbling noise would be if you have a CVT transmission and it needs a transmission fluid change or the start clutch needs to be looked at. There's a procedure called "burnishing the clutch" where they do a multiple trans fluid change that might help. They did this with my car, and the grumbling sound it was starting to make when shifting at low speeds was eliminated. There's a Honda service bulletin that the dealership should know about. It refers to "judder" or "slippage" with the CVT transmissions in the older models. There is a warranty extension involved, but I think it goes up to 100,000 miles. In some cases, people have had some luck getting certain jobs done cheaper than originally quoted:

https://www.greenhybrid.com/discuss/...one-out-20179/

I'd try the cheap stuff first, like changing the cabin filter. It probably needs to be changed if it hasn't been done anyway.

 

I'll ask them about the cabin filter. I had the clutch thing flushed already. I don't think oxygen sensors are the problem because the gas mileage has remained about the same it has always been. Do you know about how much it is to get the cabin filter replaced?

 

Wheel bearings worn out !

ks

 

See Kevin's post above, and have the wheel bearings checked.

As for the cabin filter, my dealership was going to charge $80 to change them; I've seen posts where other dealers charge more than that. I bought the filters at the dealer's parts window and they printed up a picture from the service manual so I'd know where they go. To do it myself cost $40, but you can buy the filters even cheaper at an auto parts store. I did that for my daughter's Civic, and the total cost was only $16.

 

My 07 had rocks in the plastic shields under the passenger compartment. I removed all the plastic shields and got about a kitchen garbage can full of small rocks ( like they use on icy roads and small gravel that they use to fill potholes ) the sheild for the gas tank had the most.

I bought it used and suspect someone tried to do doughnuts in a gravel parking lot. you could not hear anything on smooth roads, but on bumpy roads, it sounded like the drivetrain was failing.

if you do this you need to get some of the snap holders that hold the panels in place as I broke 8 of the 50 that hold them in place. - It can be a one man job. watch were things are. the gas tank one was the hardest to put back as the muffler wants to interfere with the installation.

 

It does it even when the car's not moving though - that wouldn't be wheel bearings, right?

 

No, I suppose not.

Maybe it's a vibration of some sort? My car, when it's cold, will grumble a bit when I'm sitting at a stoplight in gear, and if I put in into neutral the grumble goes away. So I figure it's some sort of vibration. After it's warmed up, it sounds fine. Not sure if that's anything like what you're experiencing. I don't have any grumble while driving, just one time while driving about 55 mph on the highway just after I had my snow tires put back on. They rotated them and the grumble didn't come back.

 

I think it might be the cabin filter that was mentioned earlier. I drove it from KS to Nashville in October and had the oil changed before I left. At that time, the mechanic said that I needed to get that filter replaced because it was pretty dirty. I'm wondering if that wasn't the filter he was talking about. So I'll see Monday. Thanks for all of your suggestions! I have looked on this forum for so much it's been so helpful!! I take it in Monday, so I'll update you and let you know what it was.

 

There's an air filter under the hood as well. Maybe he was talking about that one, or the cabin filter inside the car. Maybe both.
Good luck.