Humming/Buzzing when moving

My csvt started a humming/buzzing noise when in motion. I have been suspecting the wheel bearings are in need of replacement for some time now and with the buzzing/humming noise occuring only while in motion my father and my mechanic agreed so I had the wheel bearings changed but the noise remains. The mechanic seems to think that it is coming from the tranny and he is hooking me up with a free diagnosis from the tranny shop he uses since he is a friend of my father and a trust worthy mechanic. My question is, what do you guys think?

Details:
-the car has 104,9?? miles with the original tranny/clutch/engine
-the engine sounds fine
-the clutch feels fine to me
-the humming/buzzing occurs only when in motion and is directly related to vehicle speed. the faster the speed the louder the noise
-new wheel bearings sourced from Bill Jenkins made no difference
-the noise is coming from the front left side of the vehicle
-the tires were rotated with no change to the noise
-most posts I have found both in the new and old forums state the wheel bearings are the culprits but that is not true in this case

could be a CV joint as well.

oh yeah, i forgot. the half shafts on both sides were replaced about 1.5 years ago but I have never been convinced the driver side was right even though they tell me otherwise.

update...

the tranny shop says it is a bearing in the trans that is failing. without tearing it apart they cannot say which bearing and recommend replacing them all which they claim will run between $1000-$2000. I can have a new tranny from Bat for $1195 and installed for $6??.00 (I forget the exact number quoted but it was 600 and some change). I do not have the time, tools, place, or experience to do this myself so that is not an option. anyone have a better idea?

update...

I trust my mechanic but I do not know the guys at the tranny shop he uses so I got a second opinion from my fiance's step brother who is a mechanic at a Kia dealership. He said the noise is a failing throw out bearing which makes much more sense given the finicky nature of our cars with regards to throw out bearings. I will get a third opinion I can trust and see what that brings.

I had a bearing go inside a manual trans (non-Ford) years ago. How are the engine mounts? Although, you would hear engine noise when not moving too.

Updated Details:

-the car has 106,??? miles with the original tranny/clutch/engine

-the noise resembles a bad bearing. not a chatter, clatter or clank but a consistant whirring type noise audible both inside and outside the car

-coasting while the clutch is pressed and held to the floor and the shifter sitting in any gear makes the noise disappear approximately 95%

-coasting in neutral with my foot not touching the clutch makes the noise disappear approximately 95%

-when idling (vehicle on but not moving) there is no noise

-at walking speed (in 1st) there is no noise

-the clutch feels fine to me with regards to pressure

-the noise only occurs when in motion and is directly related to vehicle speed. faster speeds result in a frequency increase in the noise

-new wheel bearings sourced from Bill Jenkins made no difference in this regard

-the halfshafts were replaced in feb 2006 and the drivers side, that i never trusted, was replaced again during the wheel bearing replacement in august and had no impact

-the noise is coming from the front left side of the vehicle

my uneducated guess is either a bearing in the tranny is going or a bearing in the clutch, throw out bearing, is going bad. my brother in law mentioned previously in this thread thinks it is a throw out bearing. Another knowledgeable ceg'er suggested it might be gear roll over. the tranny shop my mechanic uses says it is a tranny bearing and want $11??.?? to replace them all. I have not had the time to get another opinion from a tranny shop as I said I would but I have communicated with a couple of knowledgeable ceg'ers as well as 2 friends of mine with strong knowledge/experience in this area.

The following is a repost of a pm I received from warmonger after I approached him for an opinion.

Warmonger said:

Please just feel free to repost this in the thread you started and put my name on it. It is only my opinion gained through my experience so take it FWIW.

Well it does sound drivetrain related but my first thought would just be the normal Audible gear whine associated with ALL transmissions both new and old but more so as they get older. This comes from increased play in the gears from wear and you get a bit of hum or whine on decel or slight load changes. Usually it comes from the final drive ring and pinion gear. I think it is possible it could be a bearing but from your description it is rather unlikely since a shaft bearing is spinning all the time at various speeds you'd be hearing it more often. If it is not specific to one gear then it is not a bearing for a specific gear and that would mean it was a shaft bearing of some sort but again I'd expect noise the whole time you were moving or at idle. So personally I think the transmission guy is looking for a bit of work.

If that is what you hear but your transmission works otherwise fine then just service the fluid again and use a bit thicker fluid. Definitely don't use ATF anymore because it does not provide much pressure protection. There are several GL4 and GL5 fluids out there that will not hurt yellow metals but will cushion the gears very well.
I recommend Torco MTF for most applications unless you get really cold out. The ford "Honey Colored" replacement fluid is made by castrol and is very much like Redline MT90 gear oil/fluid. Either of those are both good choices. If you are racing a bit then Torco RTF comes to mind as good fluid but it is actually a bit thinner than the MTF and won't provide the noise reduction that the others do.

Click to expand...

Since I approached Warmonger over the weekend the noise changed from being nearly absent when coasting to being reduced but still clearly audible. I am convinced it is something in the tranny itself but rather than jump to the most expensive idea I am gonna start with the cheap and easy stuff. To that end I am going to replace the fluid in the tranny with the honey and see what that does since I cannot remember what is in there now.

JB1 said:

Since I approached Warmonger over the weekend the noise changed from being nearly absent when coasting to being reduced but still clearly audible. I am convinced it is something in the tranny itself but rather than jump to the most expensive idea I am gonna start with the cheap and easy stuff. To that end I am going to replace the fluid in the tranny with the honey and see what that does since I cannot remember what is in there now.

Click to expand...

Check my signature.

I once had a strange ticking noise that nobody could solve and it ended up being my ABS sensor... somehow the magnetic part of the unit was touching the CV joint. Maybe thats something to check out.

i don't think it's the throw bearing. i had one of those go out once and the noise it makes is directly related to engine speed not vehicle speed, even in neutral, because the bearing spins, even in neutral. if it were the throw bearing, you should be able change the sound by lightly pushing on the clutch...

Resolution – I realize it has been sometime since the beginning of this thread, but I finally have a resolution which may or may not prove useful for anyone who has the same problem. Since I didn’t have the money to guess at which part(s) were failing, it was decided to wait and see which part failed. Well something finally failed, the slave cylinder. Not the part I expected to fail. When the mechanic took everything apart, he said the throw out bearing was toast and likely caused the sound. While we had everything apart, I decided to have the tranny guys crack open the case just to be sure. As it turns out, there was a bad bearing in the tranny as well as some bad synchros. I already figured the synchos would need changing. He couldn’t remember off hand which specific bearing was bad in the tranny, but he said it was on the output side of things and that the clutch itself appeared to have a good bit of life left in it considering it had logged just over 120,000 miles and 2 teenage girls learned to drive a stick with it.

To recap:

-Approximately 16 months passed between first noticing the issue and something failing. I do not know how much longer either bearing would have gone before failing, but I didn’t expect it to even go that long. I do not remember what tranny fluid was in it last. Most likely, either Torco MTF or Mobil 1.

-Throughout the issue, the car was a daily driver logging about 15,000 per year.

-New bearing in the tranny, some new synchros, a new clutch, throw out bearing and slave cylinder solved the humming/buzzing/screaming issue. There were a couple others things I had done, but they are unrelated.

-Either the tranny or the clutch individually could have caused the problem. Since the charge to inspect at the tranny was only $150.00 (in my case), it would be foolishness not to have it at least looked at while you are in there considering how much work is required to take everything back apart if you are wrong in your initial analysis.

Glad this finally got resolved, James. Nice to hear from you again. How's married life? It looks like I'll be finding out pretty soon myself! :shocked: