I own a base model H3 with 150k miles. I have owned it since new and have had the transmission replaced and a top end rebuild about 30k miles ago.. I had a strange thing happen yesterday where I was driving and noticed slipping in drive, like the truck went into neutral. I tried manually shifting down but same symptoms. I pulled to the side of the road, placed it into park with the engine idling and inspected it for leaking oil…none. Checked the oil level…perfect. I got back into the truck put it into drive and to my surprise it operated perfectly again and I drove home. What in the world? Seems like I lost pressure and then it came back after sitting and idling. Anyone have any ideas? Oil pump? By pass valve thingy? Kinda afraid of driving it thinking I might get stranded.

 

Was the Trans replaced with a new one, remanufactured, or rebuilt unit?

You stated you checked the oil level, did you check the Trans Fluid level and quality via the color & smell test?

 

Thanks Doc Olds, Remanufactured. Oil has less than 5000 miles on it and is in good shape bright red no burnt smell.

 

Did you check when the transmission fluid was hot, warm or cold? Make sure you you check on a level surface and against the correct level for the temperature. Had a similar experience with a new 4L60E where i needed to top the fluid up. The breather tube was also blocked causing incorrect fluid level readouts.