Blown transmission
 

Was driving my 2006 I5 H3 on the highway about 70mph and all of a sudden it felt like both front tires blew out or I had hit series of unseen big potholes. Then it got smooth again. I coasted over to the median put the truck in park and opened the door to look and it started rolling. I put it into drive and revved the engine and got nothing. No gear worked and it kind of whined and felt like it was slipping when put back into park. I thought the transmission went out, towed it to my service place where they confirmed the symptoms. Then when they took it off the rack they started it, put it into reverse and backed it out. It seems to have fixed itself. So it seems not to have been the transmission or anything mechanical but probably some sensor or electronic issue. However, it didn't throw any codes. Any guesses?

That is strange. I was driving my folks 2000 Mercedes ML320 SUV in town and when I was driving over a bridge, the engine lost power and coasted to a stop. I waited about 5 minutes to start the engine again and it started but when I put it into drive, it turned off again. I had it towed to the mechanic and they said a temperature sensor in the engine block became faulty and had to be replaced. They said that that was a rare occurance, but it does happen. Its a quick fix at about $300! Im not sure why you had the knocks or shimmys if it was a sensor of some sort. Maybe its time for a major serviceing depending on the miles you have on the truck?

Effin gremlins

I would be having a second opinion on the matter, That definitely sounds like a tranny problem

I would also recommend getting a second opinion. I can also look into this for you with your VIN. Please feel free to keep me posted either way. Thank you.

Tricia, GM Customer Service.

Well I hadn't really had a first opinion yet, that is why I came here. However, it appears we now have the answer. The new information is that there was differential fluid leaking from the front right axle seal. It was a new leak evidenced by not having blowback all over the bottom of the truck. So now, it seems mechanical. When they took the seal out they found the axle bearing in pieces and the end of the axle chewed up. That seems consistent with what it felt like. The bearing blowing up could certainly account for the violent vibration and then smoothing out once it was in pieces. Not sure why that bearing should fail with 60,000 miles. My fluid was good. Maybe just it's time.

3.8 high mileage minivan. hmmm. Shoot it?

Has your concern been resolved? Please keep us posted on your progress.

Tricia, GM Customer Service.