No reverse after driving

[RoJo2]

Truck is a 1998 GMC SCSB C1500 5.7 4L60e 88,000 on the odometer.

So this morning I backed my truck out of the driveway and headed to work. On the way I noticed that the trans was not shifting at its typical points... seemed to slip into OD and then the shift points were just different. As I was pulling into the parking garage... it felt like the truck was hesitating/needing more throttle than typically required. As I put the truck in reverse to back into my spot... nothing. No sound of gear change... no rpm drop... was just like I was in neutral. I cycled through the gears with the shifter and still no reverse. Forward gears all worked. So I pushed the truck in the parking spot and for ***** and giggles I shut off the truck and then turned it back on to find it shifted into reverse.

At this point, that’s all I know. I’ve not been able to do any diagnostic yet or drive the truck again. Yesterday I took the truck on a short road trip about 1.75 hours each direction where I was consistently running 75-85 without issue and had no reverse issues. Never had any abnormal trans stuff prior to this. No check engine light either.

I plan to go through all the typical fluid level and color stuff as well as checking for signs of electrical issues around the trans... i have a cheap OBD2 tool that I’ll put on it tonight and see if anything shows up. This weekend I plan on dropping the pan, replacing the filter, and eyeballing the inners. Has anyone had this or a similar issue that was resolved without a rebuild?

Thanks for any insight.
-Rob


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[RichLo]

Your on the right track by checking the fluid level and doing a fluid/filter change right away. If its real low you will need to check all cooler lines for leaks and the engine coolant for trans oil mixed in (for an internal leak in the Radiator trans cooler)

Also, smell if the trans oil has a burnt aroma to it

 

[skylark]

A plugging filter or a bad o ring on the filter can do what you're describing. Unfortunately a plugged one usually means more issues.

 

[94burbk1500]

Definitely check fluid levels. I had a cooler line rust out and cause my truck to slowly leak fluid over time, the first gear to show any symptoms was reverse. Swapped the cooler lines, dropped the pan, swapped the filter and filled it back up, 20k miles later with some hard miles and some light towing and no issues yet.

 

[RoJo2]

Well I was able to make it home... and that’s about where the good news stops. Cranked her up and had no issues what so ever leaving the parking deck. Got her on the road and out on the interstate... a good 15 minutes or so into the drive and OD starts slipping and disappears. Made it to my exit in 3rd and all the downshifts felt fine. Started moving along in traffic and it felt like I was in 1st but when I gave gas... it shuttered and barely went. Thought I might be in second or third so I manually shifted down into first and nothing changed. Put it in 2nd, 3rd, and back in OD... nothing changed. The further in traffic I went the worse it got until finally I had no forward drive. I was able to throw the truck in neutral while coasting, shut it off for a sec, restart, and then I had just enough in it to pull it into a near by neighborhood. Parked it for 5 min and then started it back up. Put it in drive and drove the rest of the way home with no issue. Left it running in the driveway so I could check the fluid and what was bright pink a couple weeks ago is now slightly grayish pink with a hint of hot metal smell. I let it idle for a few more minutes and started to hear a noise from the trans. Got in and checked and reverse all forward gears had stopped working again. I noticed the sound was loudest in neutral and second loudest in park... almost like and exhaust leak or rattle. In any gear, the noise went away. I’m gonna drop the pan this weekend and change the filter... see how bad it is. Pretty sure it’s gonna end up needing a rebuild but if I’m lucky... and fingers crossed here... maybe the filter has some **** it in that’s starving the pump causing me to lose gears when hot and get them back upon cool down and I’ll be able to enjoy this thing a little longer before rebuilding.

Any other ideas?


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[skylark]

That crap is plugging the filter. If you shut it off the trash flows away from the filter and it is "good" for a little bit.

 

[RoJo2]

That crap is plugging the filter. If you shut it off the trash flows away from the filter and it is "good" for a little bit.

My thoughts exactly. Hopefully it’s not damaged too bad.


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[PlayingWithTBI]

I'd flush the lines and cooler(s) too. You may wind up plugging the filter again if you don't get out as many contaminants you can (unless you can drain the TC too).

 

[RoJo2]

I'd flush the lines and cooler(s) too. You may wind up plugging the filter again if you don't get out as many contaminants you can (unless you can drain the TC too).

At this point... if a filter fixes/masks the issue... I’m gonna be changing it at the same intervals as my oil filter.


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[94burbk1500]

You might be in for a rebuild, but you can always flush and hope.