Transmission issues?

[gmartin1215]

I have a 2009 Tahoe 4x4 with the 5.3 and the 6l80 with 150000 miles.

Recently, the transmission has started having issues where it slips out of gear, or does not engage it. This has happened after stopping at a light with the front pointing up on a slight incline. I roll out in first gear, then seem to not engage the 2nd or 3rd gear where I am only revving the engine, like its in neutral. Eventually, after the vehicle has slowed down a bit I can get it to engage again and I can continue. Shifting and driving go back to normal. There were no codes thrown and I did not hear any clunking or popping. This has happened to me twice. When I got it home, the first thing I checked was the fluid level. At running temps (140 degrees), I did notice the fluid showed that it was at the bottom line of the area with hashes that say "Hot." I added a bit more fluid and have been driving around for the last couple days (at about 120 degrees) and have not had the problem occur again. I have not noticed any leaks.

I am suspecting there could be more going on than low fluid, but hoping that is all it was. What are some other diagnostics I can do?

 

[Joseph Garcia]

@NickTransmissions

 

[Doubeleive]

start saving money for rebuild, a little bit low on fluid shouldn't be any issue at all and it shouldn't ever be low unless there is a leak somewhere, transmissions do not "use up fluid" like a engine will burn oil.
if you plan to keep the vehicle find the best rebuilder in town and get a quote. A good shop will know all the fixes that are needed to make the 6l80 last and the cost will likley be equal to or better than one from the dealer.

 

[gmartin1215]

start saving money for rebuild, a little bit low on fluid shouldn't be any issue at all and it shouldn't ever be low unless there is a leak somewhere, transmissions do not "use up fluid" like a engine will burn oil.
if you plan to keep the vehicle find the best rebuilder in town and get a quote. A good shop will know all the fixes that are needed to make the 6l80 last and the cost will likley be equal to or better than one from the dealer.

Yeah, I am starting to think that it will need to be rebuilt; I am planning to keep it.
The low fluid could be because of me. I changed the fluid about 5000 miles ago and it is possible I did not get enough in. I did put half a quart in the other day where it's now registering on the higher end of the Hot mark. So far, the transmission seems to be doing okay, and I varied my driving from easy starts and also at WOT. But, the issue I described earlier has been infrequent, and it just started doing it. the first time, I came back from a long drive, and then started hitting street lights on the hilly part of town, and that's we the first time happened.
I'll start looking for reputable tranny shops in my town.

If there are other diagnoses I can check on please let me know.

 

[Doubeleive]

Yeah, I am starting to think that it will need to be rebuilt; I am planning to keep it.
The low fluid could be because of me. I changed the fluid about 5000 miles ago and it is possible I did not get enough in. I did put half a quart in the other day where it's now registering on the higher end of the Hot mark. So far, the transmission seems to be doing okay, and I varied my driving from easy starts and also at WOT. But, the issue I described earlier has been infrequent, and it just started doing it. the first time, I came back from a long drive, and then started hitting street lights on the hilly part of town, and that's we the first time happened.
I'll start looking for reputable tranny shops in my town.

If there are other diagnoses I can check on please let me know.

the only thing you can really do that may affect transmission shift behavior is to clean the intake, new air filter, clean the maf or replace it, clean the throttle body.
the maf is something that can have a direct effect on shifting "if" the problem is not in the transmission. the maf can cause a variety of issue's but chances are slim of it being the cause luckily even if just throwing one on it for the hell of it, the cost is not a lot depending on the year you can find a new oem online for anywhere from $75-150
my experience has been that the maf can start getting funky at around 160k

 

[gmartin1215]

the only thing you can really do that may affect transmission shift behavior is to clean the intake, new air filter, clean the maf or replace it, clean the throttle body.
the maf is something that can have a direct effect on shifting "if" the problem is not in the transmission. the maf can cause a variety of issue's but chances are slim of it being the cause luckily even if just throwing one on it for the hell of it, the cost is not a lot depending on the year you can find a new oem online for anywhere from $75-150
my experience has been that the maf can start getting funky at around 160k

Ok. That's worth a try.
The only things I changed recently before the tranny started acting up is that I changed the driver side rocker cover and added a catch can. I was starting to wonder if the catch can could be the suspect and maybe some vacuum leak but hoses are all snug. I could always throw the old pvc hose on and bypass the catch can, but honestly I'm thinking this may be this least suspect. But I could be wrong. I am having trouble believing this could be the cause, but things did start acting up after I put the catch can on

 

[89Suburban]

@NickTransmissions

 

[NickTransmissions]

Yeah, I am starting to think that it will need to be rebuilt; I am planning to keep it.
The low fluid could be because of me. I changed the fluid about 5000 miles ago and it is possible I did not get m mel enough in. I did put half a quart in the other day where it's now registering on the higher end of the Hot mark. So far, the transmission seems to be doing okay, and I varied my driving from easy starts and also at WOT. But, the issue I described earlier has been infrequent, and it just started doing it. the first time, I came back from a long drive, and then started hitting street lights on the hilly part of town, and that's we the first time happened.
I'll start looking for reputable tranny shops in my town.

If there are other diagnoses I can check on please let me know.

Check out my 6L80 Information thread (link in my signature) and make sure whichever transmission shops you talk to know these transmissions and all their proclivities. Being a quart low usually won't produce drivability symptoms unless at WOT or maybe towing super heavy loads up grades. But individual transmissions will react slightly differently to a mild low fluid condition so you never know. You can always stick a bi-directional scan tool on, bring up the transmission live data screens and drive around with it to see if you observe any anomalies (longer than usual shift times, TCC efficiency, duty cycle, etc) and deep scan for codes that basic code readers won't catch. Any Snap On scanner or equivalent should give you the info you need.

Otherwise, just keep an eye on it...If it starts to slip, flare and/or "false neutral" again, scan it for codes and drop the pan to look at bottom for clutch material, kibbles and bits. If you see anything like that, bolt the pan back and yank it out for overhaul.