noise getting louder and deeper
 

Hi folks,
stumbled across this forum, and really hoping to tap into some knowledge with a problem I have with my car. I have an Accord 1.8 petrol Vtec Sport 52 Reg (manual transmission), with 96k miles. I noticed a humming noise coming from underneath the car recently, which didnt seem to be a problem, until after I just came back from a 1700 mile trip around Scotland. I noticed that the noise has become much louder and deeper in tone. It sounds like an exhaust blow but if I hold the cluch in and freewheel it still makes the noise, which I have never had with exhaust blows before. It isnt tyre noise either, my lovely quiet car now sounds like a 18 wheeler :-( It gets louder and higher pitched the faster I go and doesnt really kick in till about 30mph. Is this something anyone else has had and knows the solution to? or is it an expensive trip to the mechanics? Any help would be hugely appreciated.
Mark

Welcome new member!

You sure it isn't tire noise?
What about wheel bearings? Can you tell which corner is noisy?
Usually wheelbearings increase & decrease noise when you turn, but it doesn't always happen that way.

What's "52 Reg"? I don't know what that means...

Thanks for the welcome Jim. Almost certain it isnt tyre noise its too loud, and has changed from a higher pitched whine type noise to a lower hummm type of noise, which you can almost feel as you are driving through the steering wheel, definitely an engine type noise, not coming from any particular side, more under the engine, and definitely nearer the front of the car. Sorry about the 52 reg (UK thing) its a late 2002 model. Another thing to add too, is that if the car is sat idle and you rev it, it doesnt do it, only when its moving (over about 30 mph / 48 kph). Thanks

Is it the area where the drive shafts hook into the tranny? Did you check the drive shaft boots? Is the differential part of the tranny and lubed by the same oil?

The differential IS part of the tranny & lubed together with the entire tranny. Location of noises is really funny inside the car since the structure & soundproofing makes the sound travel in funny ways.

Swap tires around to see if the sound moves around (to really rule out tires).

You said you can coast & still hear the noise, right? Here's your assignment...
1) Drive along (windows open or whatever so you hear it best).
2) Press clutch pedal & drop to idle RPM while coasting.
3) Try again but this time shift to neutral & let out clutch pedal.
Describe noise differences 1 vs. 2 vs. 3.

You could also support the front of the car, start the engine, idle in 4th gear & listen at each wheel. (Don't get your head caught up in the wheels :O) Sometimes a wheelbearing won't make the same noise if it's not loaded by the weight of the car. But tranny/differential noise should be the same as coasting.

I once had a bad wheelbearing (89 Saab) that sounded just like big knobby mud tires like you'd put on a jeep. I blamed it on the snow tires I just got, but then it didn't go away when I put the summer tires back on...

Thank you Jim, I'll have a go in the morning, and will post my findings tomorrow :-)