Bcolpablo

We have a 2007 Silverado Z71 4WD 5.3L, had a massive oil leak come about a few months ago. I didn’t inspected and was told that it was going to be a rear main seal that needs to be replaced as well as the seal case gasket. Over the period of the summer we replaced the rear seal, the oil pan gasket, the oil of lift tube gasket, transmission pan gasket transmission filter. Other than that, there are some other hardware that we replaced like the CV axles, etc. once everything was put back together, we took it for a test drive and noticed reversing out of the driveway seemed difficult, but we were able to take it down the road. Also noticed that it seem like it was wanting to start off and second or third gear test. seem to be working OK just that for some reason the lower gears were not working properly. At that point, my son went to take it to school the next morning. Got about 5 miles down the road, he had it in “auto” four-wheel-drive, and it kicked it into neutral on the transfer switch.

Once I got there, I was able to get it into 2 Wheel Dr. but it would not go into reverse. I eventually had to put it in four wheel high just to get it to start moving forward. Once I got above 25 miles an hour everything seemed to be fine as it was moving and accelerating bogging down a little bit. Once we got it home first thing I did was check fluids. The transmission fluid seem to be a little high. I pulled little over a quart out of the dipstick tube with an evacuator. Still no result. During the removal of transmission, we did not move the torque nor touch anything, but the harnesses, it literally was only disconnected for approximately four hours in between removal of the rear, remain seal and gasket installation and then reinstall installation of the transmission.

Had a buddy who has worked in the shop for 20+ years and the only guy I trust working on my diesel, he has a nice scanner come over last night, nothing scanned wrong no error codes. We disconnected the linkage, put everything in gear manually from underneath the transmission and the same thing continue to happen. We jacked the rear end up, allowed the back tires to hang free, put it into reverse and the rear tires slowly turned forward. That’s when we noticed if the vehicle is in park and we go to rev the engine it acts like it’s under load and doesn’t allow the RPMs to free range. In neutral you do get the free range rev of the engine. I have watched so many YouTube videos and talk to multiple shop mechanics as well as been too many forums and can’t seem to get an answer. I’ve noticed many people I’ve had this problem, but no one has posted what the cure to this is. I feel that this is something simple that maybe everyone is overlooking or something that is just a common mistake that no one thinks about because everything technical has been gone over multiple times by a person as well as computers. We can’t seem to locate a problem, but obviously there is one. So any help would be greatly appreciated.

Bcolpablo

Update on this, we took the transmission pan off and found that the 1-2 solenoid Was damaged either when putting the pan back in or taking it off originally. We replaced both the 1-2 solenoid and the 3–4 solenoid. We do have first gear again but reverse is still acting like it’s under load but when getting the RPMs up around 1500 to 2000 it starts creeping forward inches at a time. Neutral free ribs, but still wants to act like it wants to itch forward as it free revs, and then park is acting like it’s under and will not let it free rev any suggestions or help would be greatly appreciated.