13 speed shift troubles when cold

Well... if shes cold and arthritic when cold, thats the fluids, oils and greases cold. Ive had many trucks in my lifetime that would need about 20 miles of nursing until they get limbered up and at temperature. Once the axle and trans temp get to about 210 and the engine oil temp to 190 it's time to put her to work and she will run well, or should.

 

Should not have an issue at all splitting in any temp. Sounds like it splits fine in the rest of the gears but only have issues with 10th/11th.
Interesting

 

Looks like a red flag to me.Something isn't right. Like what was said tranny's are made to do their job if it's cold or hot shouldn't make a difference.

 

My last Truck, a 99 13 spd did that, wouldn’t split up when real cold. I’d run it till it was good and warm, then it worked fine. My guess is the splitter valve was sticky or lines had oil in them from compressor. Don’t know.

 

I would re oring the range and splitter pistons with new and look for oil in the air lines. If the oil is in there and cold it can delay shift. They can get dry and sticky as well so clean them up and use the oring lube supplied. Sometimes you can hear the gurgle on shift. Blow out the lines good if this is the case.

It's cheap enough to try first. Then suspect internal with no change.

 

True if it was all gears . This truck has issue with splitting particular gear

 

Old trick is if you Blip the throttle lighty after you pre-select the split it will shift. The old 13’s are known to just go into nuetral sometimes between splits. Throttle blips and patience usually work.