[himanshugoswami]

Hi Fellas,

over the last two days, I have noticed a strange sound coming from my truck. this sound comes mainly in second and third gears between 1200 to 2000 rpm. it is like a pronounced mechanical drone with a hum. (no- this is not the turbo whistle).

it seems to be coming from wither under th hood towards the left side or from the left wheel well.

any ideas what this could be.

there is no impact on the performance of the truck either in initial pick up or mid range, and the tyres are also not showing any signs of scraping anything.-also if the tyres were scraping, then the sound should have increased with increased speeds-but it goes away after a certain point.

am thoroughly confused...help

[Ignazio]

Wheel bearing? few questions... 4x4 or 4x2?
Try to be more precise with the description, goes away if you press clutch? Goes away if you put neutral? Is it speed depandant?
Ciao
Ignazio

[tsk1979]

1. Can you hear the sound at idle? Try straining
2. I suspect wheel bearings but in that case the hum increases or decreases with speed

So diagnose it as follows
1. Rev the engine in neutral see if there is hum or not
2. Go to a speed and engage neutral, coast with engine running. Try to listen for sounds
3. Find a very empty road, get to about 60kmph, engage neutral and switch off truck. Remember you will have limited braking ability. Listen for any unusual sounds

Humming sound is bearing noise. What we need to find out is which bearing? It could be AC compressor bearing, power steering pump bearing, g'box bearings.... and so on.

[suman]

Himanshu, is this only when the AC is on or even when its off? Try that & let me know.

[vikid]

Originally Posted by Ignazio

Wheel bearing? few questions... 4x4 or 4x2?
Try to be more precise with the description, goes away if you press clutch? Goes away if you put neutral? Is it speed depandant?
Ciao
Ignazio

Hey Ignazio: you have asked the right questions; i am impressed! what do you do?

the point to notice is that this humming goes away (at higher speeds). If your rig is a 4x4 then i would check the front diff, could be axle, bearings, r&p bearings, driveshaft / Ujoints.

[himanshugoswami]

Guys, thanks for your suggestions....tried everything, but the noise would not go away. then, early morning took the truck for a really long drive, on a very empty strech of road. noticed that the noise was coming only when the spped of the truck was between 50 - 70 kph- not related to the engine speed, but the road speed.

also, in the silence of the morning, the sound seemed vaguely familiar. then, i had one of those einstienian moments and decided to open and then close all the windows. did that, and then tried again, and voila! the sound was gone. turns out that the LHS front passeger window was open a wee bit- not visible to the naked eye, but enough for wind to get in. and at the above mentioned speeds, it was the sound of the wind....i guess at higher speeds, the wind deflection pattern would be altered and the wnd would not be directed towards the window and hence no sound....

so in all, khoda pahaad nikla chuha (for the benefit of Ignazio- this translates to "dig a mountain only to find a small mouse" )

will observe it for a couple of days just to be sure....

Thanks a ton!

[mobike008]

Wow, that indeed was a suprising solution for your strange humming phenomena

[suman]

, all's well that ends well. I think you should send a PM to tsk or someone so that the title can be edited suitably & the thread locked

[HotChillyPepper]

You cranked many brains here. anyways happy to see that there is no trouble with ur car. Enjoy

[nitrous]

You just disappointed the Tata bashers, himanshu!

[PAVAN KADAM]

Hey guys hold it, i have my own questions to be answered.

See at speeds beyond 120 kmph i hear the air restriction noise at my Safari windshield going Swooooshh......

Is this common or is there something we can do about it.

[himanshugoswami]

try something that I did.....on the RHS wiper, there is a wind deflector....it is fixed solid to the wiper. Put some layers of smooth tape on the upper end so that there is a bit more upwards slope that is created....voila! you will not have any air restriction noise till 140 . At the recent Team Bhp meet-drive to N'sagar dam, I was clocking 130-140 on quite a few occassions trying to catch up Mobike008's viva crdi. and the wind noise was driving me nuts, so when I got back tried this experiment out and it works like a charm.

In fact, i suspect that if the bonnet of the safari is redesigned to have a bigger kink upwards when it nears teh windscreen, it would actually improve the high speed aerodynamics of the car since it would deflect most wind flove over the huge windscreen. Also, if you observe the top of the safari's passenger cabin it is designed to create downforce in the area right above the front seats....check your truck and let me know....if only we could have access to a wind tunnel!!

now to do something about that inferal ORVM vibrations at anythn above `120!!

[mobike008]

Originally Posted by himanshugoswami

At the recent Team Bhp meet-drive to N'sagar dam, I was clocking 130-140 on quite a few occassions trying to catch up Mobike008's viva crdi. and the wind noise was driving me nuts, so when I got back tried this experiment out and it works like a charm.

Was that the only time your truck clocked those speeds?

[himanshugoswami]

Originally Posted by mobike008

Was that the only time your truck clocked those speeds?

well, buddy, I was having to control myself, cause any faster and I would have been driving OVER your viva

[tsk1979]

Note from mod: Thread closed