NH Auto Gears stuck in 1st till it warms up

[Bricktor]

Hi all,
Can someone give me a heads up?
I have an NH V6 Auto. It has an Auto Box with 60,000 kms & the engine 40,000 kms. I ran out of reverse gear & for a while I believed the gearbox was shot until I realised that if I change the oil in the gearbox I might be surprised by the result. I drained the entire box including the Torque Converter using around 12 litres of oil. I also took the pan off & changed the filter.The surprise was that I got reverse back, but the gearbox will not change out of ist until the oil is hot. Once the oil is hot the gearbox performs in all gears perfectly. Before I changed the oil, the forward gears worked OK. I just didn't have reverse. Can anyone shed some light on this?

[aussieintas]

Hey bud, did you flush through to remove all or most of the old oil? Also once changed did you run it through each gear whilst stationary for a few seconds to bleed it through each valve?

[Bricktor]

Hey bud, did you flush through to remove all or most of the old oil? Also once changed did you run it through each gear whilst stationary for a few seconds to bleed it through each valve?

Thanks for your reply aussieintas. Yes I did remove all the old oil., But I didn't run through the gears as you suggested. I will try that out & see what happens

[aussieintas]

Worth doing it a few times back and forth from park stopping in each gear for 5 to 10 seconds including neutral. When ive done mine in the past being a bit OCD i normally do it 3 or 4 times. Once done be worth checking oul level again just to make sure bud.

[Bricktor]

Thanks for your help. Unfortunately it hasn't responded & I have now lost Reverse again. I have come to the conclusion that the gearbox has had its day. I have to now decide if I want to replace the gearbox or get rid of the Car. Once again thanks for your input.