2000 tahoe z71 gmt400 4L60E

[hwhwhw]

help! transmission feels like slipping in 4th gear with anything above minimum torque...

 

[SunlitComet]

if as exactly as you described the tc lock up may be goofy either from wear or a malfunctioning brake switch. i say this because any friction components use in 4th gear is use at different combinations in others which you did not say were slipping.

---------- Post added at 09:46 AM ---------- Previous post was at 09:36 AM ----------

the only other thing i can think of is maybe a fluid circuit in the band servo is awry. even tho gear two is fine. there are multiple circuits that operate that band.

 

[retorq]

I bet entire transmission.

 

[SunlitComet]

I bet entire transmission.

you always bet a complete disaster. that way you can at least say you were partially correct instead of completely wrong.

 

[retorq]

You mad bro?

 

[Donnie Yukonie]

To be honest that is a pretty smart way of Technically ALWAYS being correct LOL, However another vote for TC

But I would check how the Fluids look , If they look fine I would move to TC problems

 

[SunlitComet]

You mad bro?

just ruining your plan to take over the world.

---------- Post added at 08:56 PM ---------- Previous post was at 08:54 PM ----------

To be honest that is a pretty smart way of Technically ALWAYS being correct LOL, However another vote for TC

But I would check how the Fluids look , If they look fine I would move to TC problems

partially, not always. unless it is always partially.

 

[_Dylan_]

I want to see moar pictures of this red Z71 beauty.

 

[hwhwhw]

more pics as requested


















Migo73... you can't just pick all the options... if I get it fixed with just TC you are wrong x3. I bet in school you liked the option E) All of the above

and retorq: it's about what step will fix it with LEAST cost. of course entire transmission would fix it. you are like the one jerk on the price is right who waits for everyone else and bids $1 higher.


I think Donnie and Sunlit have the right approach - hopefully this weekend I can get the fluids replaced and check for shrapnel. Then we will know more.

I hear aamco is pretty good with these things and they sent me a $100 coupon , anybody you guys trust (or don't) to check TC without charging too much ?

 

[SunlitComet]

i think the black and red contrast each other nicely.

---------- Post added at 04:25 PM ---------- Previous post was at 04:15 PM ----------

the only things that could make the 4th gear slippy is, if your 3 gear is nice and strong, a check ball in the wrong location in the valve body or perhaps an extra one. could also be an orifices cup plug not fully pressed. here is some info on the converter diagnosis.

The Torque Converter Clutch (TCC) is applied by fluid pressure, which is controlled by a PWM solenoid valve. This solenoid valve is located inside of the automatic transmission assembly. The solenoid valve is controlled through a combination of computer controlled switches and sensors.

Torque Converter Stator
The torque converter stator roller clutch can have two different malfunctions.

• The stator assembly freewheels in both directions.
• The stator assembly remains locked up at all times.

Poor Acceleration at Low Speed
If the stator is freewheeling at all times, the car tends to have poor acceleration from a standstill. At speeds above 50 - 55 km/in (30 - 35 mph) , the car may act normally. For poor acceleration, you should first determine that the exhaust system is not blocked, and the transmission is in First gear when starting out.
If the engine freely accelerates to high RPM in NEUTRAL, you can assume that the engine and the exhaust system are normal. Check for poor performance in DRIVE and REVERSE to help determine if the stator is freewheeling at all times.

Poor Acceleration at High Speed
If the stator is locked up at all times, performance is normal when accelerating from a standstill. Engine RPM and car speed are limited or restricted at high speeds. Visual examination of the converter may reveal a blue color from overheating.
If the converter has been removed, you can check the stator roller clutch by inserting a finger into the splined inner race of the roller clutch and trying to turn the race in both directions. You should be able to freely turn the inner race clockwise, but you should have difficulty in moving the inner race counterclockwise or you may be unable to move the race at all.

Noise

Important: Do not confuse this noise with pump whine noise, which is usually noticeable in PARK, NEUTRAL and all other gear ranges. Pump whine will vary with line pressure.

You may notice a torque converter whine when the vehicle is stopped and the transmission is in DRIVE or REVERSE. This noise will increase as you increase the engine RPM. The noise will stop when the vehicle is moving or when you apply the torque converter clutch, because both halves of the converter are turning at the same speed.
Perform a stall test to make sure the noise is actually coming from the converter:

1. Place your foot on the brake.
2. Put the gear selector in DRIVE.

Notice: You may damage the transmission if you depress the accelerator for more than six seconds.

1. Depress the accelerator to approximately 1,200 RPM for no more than six seconds. A torque converter noise will increase under this load.

Torque Converter Clutch Shudder
The key to diagnosing Torque Converter Clutch (TCC) shudder is to note when it happens and under what conditions.
TCC shudder which is caused by the transmission should only occur during the apply or the release of the converter clutch. Shudder should never occur after the TCC plate is fully applied.

If Shudder Occurs During TCC Apply or Release
If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. Something is causing one of the following conditions to occur:

• Something is not allowing the clutch to become fully engaged.
• Something is not allowing the clutch to release.
• The clutch is releasing and applying at the same time. One of the following conditions may be causing the problem to occur:
• Leaking turbine shaft seals
• A restricted release orifice
• A distorted clutch or housing surface due to long converter bolts
• Defective friction material on the TCC plate

If Shudder Occurs After TCC has Applied
If shudder occurs after the TCC has applied, most of the time there is nothing wrong with the transmission!
The TCC is not likely to slip after the TCC has been applied. Engine problems may go unnoticed under light throttle and load, but they become noticeable after the TCC apply when going up a hill or accelerating. This is due to the mechanical coupling between the engine and the transmission.
Once TCC is applied, there is no torque converter (fluid coupling) assistance. Engine or driveline vibrations could be unnoticeable before TCC engagement.
Inspect the following components in order to avoid misdiagnosis of TCC shudder. An inspection will also avoid the unnecessary disassembly of a transmission or the unnecessary replacement of a torque converter.

• Spark plugs - Inspect for cracks, high resistance or a broken insulator.
• Plug wires- Look in each end. If there is red dust (ozone) or a black substance (carbon) present, then the wires are bad. Also look for a white discoloration of the wire. This indicates arcing during hard acceleration.
• Coil - Look for a black discoloration on the bottom of the coil. This indicates arcing while the engine is misfiring.
• Fuel injector- The filter may be plugged.
• Vacuum leak - The engine will not get a correct amount of fuel. The mixture may run rich or lean depending on where the leak occurs.
• EGR valve - The valve may let in too much or too little unburnable exhaust gas and could cause the engine to run rich or lean.
• MAP/MAF sensor- Like a vacuum leak, the engine will not get the correct amount of fuel for proper engine operation.
• Carbon on the intake valves - Carbon restricts the proper flow of air/fuel mixture into the cylinders.
• Flat cam - Valves do not open enough to let the proper fuel/air mixture into the cylinders.
• Oxygen sensor - This sensor may command the engine too rich or too lean for too long.
• Fuel pressure - This may be too low.
• Engine mounts - Vibration of the mounts can be multiplied by TCC engagement.
• Axle joints - Check for vibration.
• TP Sensor - The TCC apply and release depends on the TP Sensor in many engines. If the TP Sensor is out of specification, TCC may remain applied during initial engine loading.
• Cylinder balance - Bad piston rings or poorly sealing valves can cause low power in a cylinder.
• Fuel contamination - This causes poor engine performance. Replace the torque converter if any of the following conditions exist:
• External leaks appear in the hub weld area.
• The converter hub is scored or damaged.
• The converter pilot is broken, damaged, or fits poorly into the crankshaft.
• You discover steel particles after flushing the cooler and the cooler lines.
• The pump is damaged, or you discover steel particles in the converter.
• The vehicle has TCC shudder and/or no TCC apply. Replace the torque converter only after all hydraulic and electrical diagnoses have been made. The converter clutch material may be glazed.
• The converter has an imbalance which cannot be corrected. Refer to Flexplate/Torque Converter Vibration Test. See: Flexplate/Torque Converter Vibration Test
• The converter is contaminated with engine coolant which contains antifreeze.
• An internal failure occurs in the stator roller clutch.
• You notice excessive end play.
• Overheating produces heavy debris in the clutch.
• You discover steel particles or clutch lining material in the fluid filter or on the magnet, when no internal parts in the unit are worn or damaged. This condition indicates that lining material came from the converter. Do Not Replace the Torque Converter if you discover any of the following symptoms:
• The oil has an odor or the oil is discolored, even though metal or clutch facing particles are not present.
• The threads in one or more of the converter bolt holds are damaged. Correct the condition with a new thread inset.
• Transmission failure did not display evidence of damaged or worn internal parts, steel particles or clutch plate lining material in the unit and inside the fluid filter.
• The vehicle has been exposed to high mileage only. An exception may exist where the lining of the torque converter clutch dampener plate has seen excess wear by vehicles operated in heavy and/or constant traffic, such as taxi, delivery, or police use.