Please house I drive a manual 1.6 liter 2006 nissan sunny which has served well for 7 years (bought new) recently I hear a very noisy hum when 8 Irive above 75km/hr. I can hardly stand the noise if I engage the fifth gear. I understand manual tyranny are built to last foreever, do I have to change mine? The car has jus clocked about 105000 km.

mitwitdot: Please house I drive a manual 1.6 liter 2006 nissan sunny which has served well for 7 years (bought new) recently I hear a very noisy hum when 8 Irive above 75km/hr. I can hardly stand the noise if I engage the fifth gear. I understand manual tyranny are built to last foreever, do I have to change mine? The car has jus clocked about 105000 km.

It appears there is no drop of oil in that transmission, hence, the noise.

Did you at any point run the transmission without oil? Because it sounds like the bearings inside are giving up, usually caused by oil starvation or lack of lubrication.

That manual tranny is built to last forever doesn't mean it's designed to run without lubricant. Each time you jump into gullies, there is always a chance that you could hit your oil pan or gearbox on something that could crack any of them. The seals, as they aged, could fail, especially from the bellhousing side, differential or output spline, depending on the configuration (FWD or RWD).

My point is, have you checked if there is oil in the gearbox ? If there is, did you run the transmission without oil for long before you refilled it? Did you at one point use bad oil in it?


By the way, are you sure its not your wheel hub bearing that has failed and making that noise?

Ikenna

@ikenna351

The oil level is still constant. Topped it up based on the advise of a mechanic but the noise persist. Please what do u mean by wheel hub? The gear functions properly around 60km/hr but becomes noisy as I accelerate toward 100km/hr.... can I detect the issue from diagnosis?

mitwitdot: Please house I drive a manual 1.6 liter 2006 nissan sunny which has served well for 7 years (bought new) recently I hear a very noisy hum when 8 Irive above 75km/hr. I can hardly stand the noise if I engage the fifth gear. I understand manual tyranny are built to last foreever, do I have to change mine? The car has jus clocked about 105000 km.

they might be bearings on the wheels

mitwitdot: @ikenna351

The oil level is still constant. Topped it up based on the advise of a mechanic but the noise persist. Please what do u mean by wheel hub? The gear functions properly around 60km/hr but becomes noisy as I accelerate toward 100km/hr.... can I detect the issue from diagnosis?

To isolate the the problem or culprit, take the car for a drive on expressway/highway. Push it till the noise starts. Then depress and hold the clutch pedal down or put it in neutral, without braking or accelerating the car. Let it roll, where it can maintain 100kh/h for a while without gearbox and engine input. If the noise stops, while its on neutral on 100km/h, then the gearbox is the culprit. But if the noise continues, even after the gear has been disengaged from the wheels, then look elsewhere, the transmission is not the culprit. Probably the wheel hub bearing. But note that it depends on how bad the wheel bearing has gone. When it has not gone that bad, it will need the pressure from the transmission on the bearing for the noise to be heard. But as it gets worse, it start making that noise, whether on gear or not, as speed increases.

Another way of knowing if the noise is coming from transmission or wheel bearing is by steering wheel test on high speed. When the noise starts, gradually turn the wheel to the left and gradually to the rght. A failing noisy wheel bearing tend to reduce noise when the steering is turned towards its direction (less pressure ), but will become noisier when the steering is turned to the other direction on high-speed (more pressure on the bearing). This can only tell you if any of the two front wheel bearings is the culprit. The rear wheels can be difficult to detect unless you listen carefully.

Or you can simply jack up the 4 wheels one after the other and shake them up and down. Anyone with noticeable clearance, you have found your culprit.

Meanwhile, I don't know about Nissan, but in Peugeot FWD, there is a bearing that the right side drive shaft pass through, behind the CV joint that enters the differential part of the transmission. The bearing hardly fails. But bearing hates water. Unfortunately, Nigerians like swimming with their cars. So, you may have to add to your list of things to check, but that should be the last.

Good luck.

Ikenna.

mitwitdot: Please house I drive a manual 1.6 liter 2006 nissan sunny which has served well for 7 years (bought new) recently I hear a very noisy hum when 8 Irive above 75km/hr. I can hardly stand the noise if I engage the fifth gear. I understand manual tyranny are built to last foreever, do I have to change mine? The car has jus clocked about 105000 km.

Change your gearbox. You probably ran it at some stage without enough EP manual transmission oil. No point in overhauling it cos the manual gearbox is not expensive to replace. Last one we changed was around N15k.

Car-Doctor