Humming Noise....Moving Parts

[mickod88]

Afternoon everyone.

 

i'm having some humming noise coming from the car, and i just wanna ask about before i take it to a garage to get looked at and get robbed. It started a few weeks ago, and has gotten slightly worse since then, it used to be after driving at 50mph+ but now it's pretty much as soon as i set off. I don't think it's engine related, as the noise isn't present when at Idle, but is still there when the car is moving, and i put the foot down on the clutch. Any ideas?

Thanks in Advance!

 

Mick

[mac801123]

Sounds like a gearbox whine. If it gets worse then it may be terminal if left. If the noise only happens when the clutch is in then I would say the release bearing but as its happening all the time the car is on the move then it's more likely to be gearbox related.

[mickod88]

new gearbox then do you think?

[ZetecMan1]

Could be a wheel bearing or a seized brake caliper.

Get it to a garage and see what they say and then take it to a second garage for a second opinion before you spend any pennies.

[isetta]

does it change note if you are applying power compared to having foot off the throttle like when going downhill ?  if so, sounds more gearbox/diff related

does it change according to load/weight on the car? like if you go off a hump backed bridge does the noise disappear as the weight lifts the load off the wheels and then get worse as kind of land and the load on the wheels increases? I know this is harder to test depending on what roads you have available to drive on. But if it does this (changes note) it is more an indication of wheel bearing

 

I assume you have checked your tyres and it is not because you have an underinflated tyre

[Tdci-Peter]

On 28/12/2016 at 3:40 PM, mickod88 said:

humming noise coming from the car, and i just wanna ask about before i take it to a garage to get looked at and get robbed. It started a few weeks ago, and has gotten slightly worse since then, it used to be after driving at 50mph+ but now it's pretty much as soon as i set off.

I also have a droning / humming noise, it also started to be audible at about 50mph, now it is all speeds over about 30. It has got steadily worse over the last 1200 miles or so. It is the same in all gears, and in neutral with engine idling (downhill at 50). It is not appreciably dependent on throttle, or on cornering. It might be getting a bit changeable with humps & cornering, but hard to tell (safely! I could do with a test track.)

I have monitored the gearbox with a mike, it gave lots of whining noises under load, which were torque & gear dependent, but went pretty quiet with throttle closed, so it does not seem to be the source.

I have swapped tyres front to back, and topped up pressures. No change.

I have felt & tested all wheel bearings and driveshafts. No play or roughness or noise whatever can be detected by hand.

I have looked at and listened to the intermediate driveshaft bearing.

I have stripped, cleaned, re-greased & tested the front brakes.

I have looked for loose bits (engine shields, heat shields etc.) under the car.

A garage looked at it last week. They could not locate it. They thought it was too high pitched for a wheel bearing, they expected a rumble. In trying to turn the front wheels with the engine (car on lift), they cooked the clutch, trying to battle with the traction control. The clutch still seems to work, but the stink was appalling.

It seems loudest at the front. Mikes under the dash do pick it up more clearly there than at the back.

I still suspect n/s front wheel bearing. But as that is not a cheap diy job, I am holding off till it gets a bit worse, hoping it will become detectable before it goes altogether!

If any garage has a good way to detect these humming wheel bearings (or whatever), then let us know. It is becoming a real pain in the posterior.

[ScaniaPBman]

Here's my answer to another forum member on this type of problem.

 

 

 

 

From what you say it does sound like a wheel bearing, but
which one? Here’s how I tracked down my suspicious whine.

First I just drove it around for a while, there was a faint
whine from the front left so I went straight in and changing the left wheel
bearing. Wrong. It made no difference.

Stung by this failure I stepped back a little and did the diagnostics properly.

To start with I purchased a mechanics stethoscope just like
this one for a fiver. Then I put the front of the car up on two axle stands and chocked
the rear wheels with the handbrake tight as well. Then I started the engine put
it in gear and set it running at 30MPH. The wheels are off the ground but
turning at a reasonable speed so the bearings are running round.

Next from underneath I put the stethoscope on the hub
carrier as close to the bearing as possible and listened. Then the other side, and
the drive shaft support bearing (my prime candidate for the cause of the
whine). All were humming away smoothly. If there was to be a bearing failure it
would have made distinctive noise clearly noticeable with the stethoscope.

I would suggest you do the same type of test on the rear
wheels getting a friend to spin the wheel for you while you are underneath
listening carefully.

WARNING. Going under a car which is up on stands with the wheels turning for an investigation
like this is a hazardous thing to do with all those moving unguarded parts. I
did it very slowly and carefully with someone in the driving seat at the
controls. All I can say is if you are not confident don’t do it. I told you it
was dangerous!

Well where was my whine coming from? It didn’t take me long
to pin it down from under the front.

It was the left side final drive gear support bearing way
inside the gearbox. Bad news.

If you are getting your whine on corners, this technique
should help you identify the cause with confidence. A failing bearing will be
picked up like this with no cornering load or vehicle road load.

ScaniaPBman.

 

I have had a lot of satisfaction from my stethoscope. Once you get used to a 'good' bearing noise, then a failing bearing will stand out like a sore thumb. Just keep probing around underneath and you will find the source of your noise.

[Tdci-Peter]

On 28/12/2016 at 3:40 PM, mickod88 said:

humming noise coming from the car

My droning / humming noise seems to be fixed now.

I have just had the driver's side front wheel bearing changed.

Running the old bearing up on a lathe at 500rpm (50mph equiv), I can create a similar noise from the bearing by twisting the outer race in a certain direction, so I am fairly sure it is the culprit.

[ZetecMan1]

Glad you got it sorted mate 👍

[Quint]

On 1/2/2017 at 2:20 AM, ScaniaPBman said:

 

Well where was my whine coming from? It didn’t take me long
to pin it down from under the front.

It was the left side final drive gear support bearing way
inside the gearbox. Bad news.

If you are getting your whine on corners, this technique
should help you identify the cause with confidence. A failing bearing will be
picked up like this with no cornering load or vehicle road load.

ScaniaPBman.

 

Hi, Mine appears to be this kind of error. Well, I've actually gone the expensive route by first changing the front hub bearings, to no avail. Anyway, as I was not the one really using the car daily, I had to borrow it so I could get a real feel of this problem. I noticed that if the car is in gear (D), the sound comes out. But if I coast at (N), and even maintain the same RPM (as if it were in gear, there is no sound. Therefore, I concluded that it must be somewhere inside the transmission. As I was researching, I found out that this transmission has a gear support bearing inside, which was confirmed by your post. I just would like to know if you have a part number,  just to make sure, as I only got ***** 801777 A. I come from a place where people are not too keen on using the part number, but resort to an "actual comparison" of the product at the parts shops. Hoping to hear from you soon. Thanks!