MK4 Jetta strange whine gearbox related?

I have a strange whining sound that happens when cruising at 4th and 5th gear, it sounds like the gearbox whine race cars with straight cut gears make but much quieter, it goes away if I take my foot off throttle and stop accelerating and is only present in 4th and 5th, is this normal?

no.
When was the trans fluid changed?
Are you sure its not a wheel bearing? does it get worse or better depending on the direction you turn? Its always present in 4th or 5th no matter the speed? Idle while moving?
What type of fluid was used? I think that trans has brass syncros, if it does, it needs a proper fluid or regular fluid will eat them.

Mongler98 said:

no.
When was the trans fluid changed?
Are you sure its not a wheel bearing? does it get worse or better depending on the direction you turn? Its always present in 4th or 5th no matter the speed? Idle while moving?
What type of fluid was used? I think that trans has brass syncros, if it does, it needs a proper fluid or regular fluid will eat them.

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Not sure its ever been changed, turning makes no difference and its only there when I accelerate if I coast it goes away completely, it always there in 4th and 5th sometimes I hear it in 3rd, im thinking I will replace the fluid with the one they sell at VW dealers and see if it makes it better, also when the car is cold 1st gear is really hard to shift into but goes back to normal when car is up to temp

RedLine makes a great trans fluid and is half the cost of the VW stuff from he dealer. As long as its the proper fluid type. Do some searching for your cars trans fluid requirements. dont trust the stores.
There is a nice DIY somewhere here about how to adjust the shifter as the parts wear down a bit of adjusting might be necessary. What trans code is yours?
http://www.zelek.com/diagram_charts/diagramlist.htm
Seeing as you have no idea of how the fluid is, change it, its tbe best place to start, if noise does not go away after 200 miles or so, you can try a gearbox polishing compound. DO NOT USE THIS STUFF if you dont have enough confidence in how to do so.

Random thought, check your serpentine belt. When mine was overdue I got a while that seemed to be coming from my gear box.

Yea, best to look at all the things possible, do you know someone with a lift? you could always block up the car safely and get someone to idle it in 4th and 5th gear and put a stethoscope against the transmission pan. dont toss money at it until your 100% sure.