I have elantra gls'00, it started to spit out trans fluid out of gas release valve on top of transmission, car runs just fine beside it will stay on 2nd gear then level gets low. If I add fluid, it will run like new again.
A year ago I replaced trans fluid at Hyundai dealer at 45 000 ml (it looked a little bit too old for me), and after one year (about 12 000 ml) it started doing this. So I did it again by myself (changed filter and filled w/ Hyundai trans fluid).
So I wonder if they mess up some settings at dealership because at the same time I asked them to check on ignition timing (I felt that timing was a little late and gas mileage wasn't that great), or I just have some mechanical problems. I can't say that fluid is burning or boiling, it is still red for past 5000 miles, it shifts easy and smooth.

Thanks,

 

Does it have too much fluid in it?

 

I didn't check it after they changed it, but then I noticed that it started spiting it it's still ~8mm higher then the high mark. It is a little bit higher now. I can't tall you the exact level then it quits working, but I think it is before low mark. Last time my wife had to add some and she couldn't tell what the level was.

Thank you.

 

So your wife is adding fluid, but she doesn't know what the level is? Normally you don't need to add trans fluid unless there is a leak. I think it's overfilled.

 

As for right now it is about 12mm higher then high mark on hot transmission, but I think that problem starts at about proper level. I will try to measure the exact level when this happens again.

Thank you.

 

Thats about 1/2 inch over the mark or at least two quarts too full. When the transmission has too much fluid, the fluid gets whipped into a froth under pressure and heat. The froth spits out the top (like you've seen), but froth also lacks any useful lubrication and hydraulic characteristics. The tranny will not shift correctly and it is hard on internal bearings and seals. Check your owners manual regarding the proper way to check the fluid level and then remove any excess. If the tranny still has shifting problems once you have the fluid level correct, then something is wrong with the electronic control system or the internal mechanism.