Tonyrodz's Tahoe Build Thread

[Tonyrodz]

What are symptoms of a failing torque converter? Most times putting it in gear, it's fine--but sometimes if I stop then go, or turn around a corner, it'll feel like it's in neutral. Sometimes I have to put it all the way in park, then drive and it'll be OK. The other day it felt like it went into neutral, so I revved it, then I heard and felt a thunk--going into gear I guess, then it was fine. There's no rhyme or reason that it happens--just randomly. I think it happens mostly when it's still cold. No weird smells, fluid level is good. Fluid level isn't bright red/punk, but it's not burned either. Trans doesn't run hot either--I have the Esky trans cluster. Anyone have any idea? I was thinking of changing pan fluid then throwing some Lucas in it.

 

[strutaeng]

What are symptoms of a failing torque converter? Most times putting it in gear, it's fine--but sometimes if I stop then go, or turn around a corner, it'll feel like it's in neutral. Sometimes I have to put it all the way in park, then drive and it'll be OK. The other day it felt like it went into neutral, so I revved it, then I heard and felt a thunk--going into gear I guess, then it was fine. There's no rhyme or reason that it happens--just randomly. I think it happens mostly when it's still cold. No weird smells, fluid level is good. Fluid level isn't bright red/punk, but it's not burned either. Trans doesn't run hot either--I have the Esky trans cluster. Anyone have any idea? I was thinking of changing pan fluid then throwing some Lucas in it.

Sounds like it's slipping...

No codes?

 

[Tonyrodz]

Sounds like it's slipping...

No codes?

No codes, no smells or weird sounds. I checked the dip stick again. Looks a little over filled. Would that cause issues?

 

[strutaeng]

No codes, no smells or weird sounds. I checked the dip stick again. Looks a little over filled. Would that cause issues?View attachment 423525

I think overfilled will cause foaming of the fluid, and I don't know what else.

Let's take a step back...how did it get overfilled? Did you add any fluid recently? Maybe check your coolant just to make sure you are not getting coolant in there (if you have the radiator internal cooler.)

Maybe @NickTransmissions can offer more help.

I hope it's not serious.

 

[89Suburban]

No codes, no smells or weird sounds. I checked the dip stick again. Looks a little over filled. Would that cause issues?View attachment 423525

Is that warmed up idling in park? Is so def way over full.

 

[Tonyrodz]

Is that warmed up idling in park? Is so def way over full.

Yup, after driving it for awhile. Looks like maybe it's over 1 qt. While on the highway I floored it and it was like it went into neutral. I took my foot off then gave it some gas and it was fine. I wish I knew what was going on.

 

[Tonyrodz]

I finally drained that extra qt of trans fluid. Put new wiper blades all around. ABOUT TIME!!

 

[NickTransmissions]

@Tonyrodz - being over filled by one quart or so shouldn't cause any problems and the excess would simply purge from the vent tube on top of the unit. Neutral conditions at high and/or WOT indicate apply pressure issues or worn applied elements in whichever circuit/gear that is producing the neutral condition. It usually occurs with 3-4 clurch pack in 4L60Es. I'd thread in a pressure gauge then take it for a test drive to see if you're observing a pressure drop when accelerating. You should see between 150-180psi in Drive at WOT but if you're only seeing 100-125 psi or so, that indicates wear at the pump, valve body or sealing rings/lip seals not sealing completely or an internal leak due to a structural defect in the forward drum.

 

[Tonyrodz]

@Tonyrodz - being over filled by one quart or so shouldn't cause any problems and the excess would simply purge from the vent tube on top of the unit. Neutral conditions at high and/or WOT indicate apply pressure issues or worn applied elements in whichever circuit/gear that is producing the neutral condition. It usually occurs with 3-4 clurch pack in 4L60Es. I'd thread in a pressure gauge then take it for a test drive to see if you're observing a pressure drop when accelerating. You should see between 150-180psi in Drive at WOT but if you're only seeing 100-125 psi or so, that indicates wear at the pump, valve body or sealing rings/lip seals not sealing completely or an internal leak due to a structural defect in the forward drum.

Have any how to's to thread in a pressure gauge? So whatever problem it could be, I'm looking at dropping the trans?

 

[NickTransmissions]

Have any how to's to thread in a pressure gauge? So whatever problem it could be, I'm looking at dropping the trans?

Maybe, maybe not...There's the boost valve and sleeve that can be swapped out with the transmission still in the vehicle...You'll need a small pair of interior/exterior snap ring pliers to do it but it's not difficult...A worn boost valve will cause the issues you're having as well...I always replace those pre-existing boost valve and sleeves with the Sonnax large ratio boost valve kit - it comes with a higher pressure spring for the PR valve and gives you about a 10% increase in line pressure at all throttle angles...Transgo's boost valve does the same thing...If this trans already has an upgraded boost valve then yes, more than likely you're dropping the transmission to figure out and fix the problem, but a pressure test will definitely help you narrow things down and give you some baseline data for your diagnosis...Having a bi-directional scan tool plugged in at the same time will also be very helpful.

Here's line pressure testing instructions.
You're looking for pressures at idle to be within the ranges shown on the chart for each gear shifter setting and immediate line rise up to around 150-175PSI or so at WOT.