What can I do about this gear noise?

One find a car like it and test drive it,if it has the same noise don’t worry.
If that doesn’t work sounds like a bearing might be on it’s way out,could last years and years and might pack it in tomorrow,depends on you got the money to rebuild it ,or wait and see type thing.

If the noise occurs when shifting gears and only when shifting gears it sounds like the synchromesh may be worn. Replacement of the synchromesh in the transmission would stop the noise. Just don’t try and shift at high speed and let the engine speed drop down before shifting to the next higher gear.

Welcome to Fluther.

“Gear noise” is an entirely useless description of the problem – if there really is a problem. The fact that your transmission shifts early (or late, it’s not clear) is a more specific issue, again “if it is a problem”. Does the transmission run hot? What is your fuel consumption like? And is this a recent development?

“Spending money on a mechanic” is no criterion for anything. What did the mechanic do?

When the oil was changed, was the old oil “flushed” or merely drained?

Additional information would also be helpful if anyone is going to diagnose and offer resolution to what you see as a problem: How many miles or kilometers are on the odometer? Has the transmission been rebuilt at some time? Has it been disassembled at any time by an amateur? Has the vehicle suffered any other relevant damage?

Way back in the day, with manual transmissions and differentials that had a little bit of singing, a couple tablespoons of sawdust in the oil (90 w) would take up the little bit of lash that causes noise. Of course any warranty ever on the transmission or differential would be voided but we are talking old beaters we were playing with.

Please specify. Is third gear the top gear? No forth? Automatic transmission? Manual transmission? How many miles are on the car?

My Corolla can barely make 3rd gear at that speed without stalling out. If your Alto is geared nearly the same, odds are that you’ve been forcing the engine to below idle speeds, and over time, that sort of abuse wears on the gears. Try shifting a little later and see if that makes a difference by not putting so much strain on it.

@kritiper thanks for the response, this occurs normally in 3rd gear, manual transmission car, i bought from someone else this car some 6 months ago, it has surfaced around 90k km

@CWOTUS thanks for the response, i am just getting idea, i noticed this kind of noise around 3month ago, i have also recently changed its gear oil named as zic gear oil korean brand, mechanic replaced its bearings, i have no idea about the rebuild of transmission may be but am not sure, because i opened all gear box from mechanic and he okayed it but still same problem persists, new gear is very expensive, i have no any other option except going for repairing or any other shortcut may works. car is good is overall running but except this noise.

@ashfaque Is third gear the highest gear or is there a forth gear?

@kritiper there are total five gears and one reverse gear in this car

@ashfaque Is there any letters on the shifter for 5th gear that says “OD?” (overdrive)

@kritiper Given that it’s 3rd gear that seems to be the issue, I think whether it’s 5 or 4+1 has no relevance. Now, if it were 4th gear, that’d be different. (Of course, it could be 3+1 forward plus Reverse for a total of five….)

@kritiper total 6 gears, 5 forward and one reverse, it is some time awkward to hear this noise i wanted to get rid of it

@ashfaque OK, I’ll assume that 5th gear is overdrive because I have a 91 Nissan with a 5 speed manual and the 5th gear is ID’ed as overdrive in the manual’s exploded view of the transmission, and not so on the shifter.
I believe the noise is coming from the roller/needle bearing (called a pilot bearing in my repair manual) between the input shaft (main drive gear) and the mainshaft. It gets noisy in third because the load of the engine is being transferred up from the counter gear to the third gear from just behind this bearing since 3rd gear is directly behind this bearing. 4th gear isn’t noisy because the input (main drive gear) and the mainshaft are locked together and are driven 1-to-1 in 4th gear (no load at all in close proximity to the bearing and no load is transferred through the counter gear in 4th).
You can rebuild the transmission using a new bearing, but you should also replace the input shaft (main drive gear) and the mainshaft. Or find a good used transmission. You can also try replacing the gear oil with a heavier, higher viscisity oil such as 85–140 SAE instead of 85–90 SAE.

@jerv Reverse gear is never considered as a gear in manual or automatic transmissions. A 3 speed automatic has 3 forward gears. A 4 speed manual has 4 forward gears, usually with 4th being straight 1 to 1 drive though the transmission. On a 5 speed where 5th is overdrive, 4th is 1 to 1 and 5th is a special extra gear on the end of the mainshaft so the output is less than 1 to 1 drive ratio. Since all transmissions need a reverse, it isn’t necessary to include reverse as a “gear.”

@kritiper Not by mechanics, no. But laymen might count it; I’ve seen it before.