Auto trans jumps out of gear.

[LouisF Junior Member Find all posts View Profile Close LouisF]

My truck has developed this tendency to just sort of jump out of gear or perhaps more like losing drive when cold. It is of course winter up here and minimum morning temp is in the region of 2°C to 4°C. The truck sleeps in a carport. When I reverse first thing in the morning, suddenly there is no drive, as if transmission is in neutral. When I take the revs a bit higher – slightly over 1000 r/min – she gives a thump from the transmission and starts moving again. Putting her in D to move off, the same thing happens. After that no more problems until I start her up in the parking cellar at the office. Exactly same symptoms.
ATF is at the correct level and is fairly new, having done less than 10k km (6k mi). Any ideas on what could cause this. I was thinking of tightening up the “kick down” cable, for that would increas pressure in the transmission, but first want to know fwhat you guys think.

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Is the fluid circulating in the trans, as what you are saying is just like when there is low or no trans fluid.

[LouisF Junior Member Find all posts View Profile Close LouisF]

How will I find out if the ATF is circulating, apart from puling a pipe off and starting the engine?

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Might be easier to just take it to an auto trans specialist, if it is a blocked filter they can fix that on the spot

[LouisF Junior Member Find all posts View Profile Close LouisF]

One answer I got from more than one source was that I should drain the ATF, replace the filter inside the 'box and fill up with new ATF. I did that this past weekend. Opened the drain plug Friday night and let her drain all through the night, about 5.5 l drained and when I jacked up the car’s nose some more drained and even more once I had the sump off. Next morning started to remove the transmission's sump. It dropped easily enough but could not be removed entirely because it got stuck between the crossmember carrying the ‘box and the front anti roll bar. After the filter was removed by undoing the 4 x 6mm bolts, it was possible to get the sump out. Spilling some ATF where I did not want to in the process…

After cleaning the sump inside and out and scraping off the sealant – mostly on the sump, but some on the bottom of the ‘box as well – the sump was ready to be replaced. I bolted the new filter in place, but really did not want to do the reverse of the process when removing the sump. The car was jacked up in front with the axle stands under the chasis just inboard of the mountings of the wishbones. Contemplating the situation a bit the sollution dawned on me; put the axle stands under the wishbones! This caused the anti roll bar to move downwards and forwards and voila! the sump could be replaced without any hastle.

And the nonsense of the transmission to lose interest in the mornings so the car comes to a standstill is a thing of the past - for now, at any rate.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Always good when it turns out to be a cheap and easy fix. And saved yourself some $$$ in the meantime doing it yourself. Don't forget, to get the right level the transmission must be at correct temperature (sure your aware of this)... Cheers Steve

[LouisF Junior Member Find all posts View Profile Close LouisF]

Yes Steve I am aware, but thanks for sharing anyway. Also, selecter must be shifted one by one through all the different positions P to L and back before checking. Whith engine running.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

All good mate glad it's all ok.... Cheers Steve