the transmission in my 08 C6 occasionally feels like there is a slight stall to it or a disconnect to the lock up.. like when I am coming to a stop sometimes (not always) feels like it 'coasts' in (tach drops to idle and there is not engine braking feeling). Also, occasionally, when I'm taking off from a stop, especially 1 right turn in particular that I noticed it at a stop sign, it feels like there is a bit of 'lag' before it hooks up.

is this normal or something I should be concerned about? No dip stick to check for burnt fluid, or friction materials, or metal... so I'm kinda dealing with a 'black box' and don't know if there is something wrong with it.. or if it's normal. Mileage on the vehcile is < 28k. All stock, except for a cat back and a aftermarket air cleaner.

any insight from more experienced C6 drivers would be appreciated

thanks!

 

Sounds like the fluid is low or low pressure. Did you have a look to see if there is a leak?

 

yup.. looked.. no sign of leaks...

dealer check? is there a line pressure sensor that can be read on it via the ECM or ?

thanks!

 

The fluid level can be checked but it has to be done with the engine running, car level and from UNDER the car!
A tech 2 could read trans line pressures. If your car is older then perhaps you should try flushing the aux cooler and change the fluid and filter. Could be a lot of things. There are several solenoids and check ***** that can malfunction or not seal. Keep in mind I don't work on transmissions but my brother has engineering experience there. First thing he always does is smell the fluid and look at the color. Brown fluid and or a burnt smell can indicate worn components (usually bands). Something you might want to try at home is get under the car and loosen the trans fluid check bolt just enough to let a little fluid run out on your finger. DO NOT take the bolt all the way out as the fluid will pour out and a LOW FLUID condition might then exist. Let just enough out to see and smell it. If you have any new trans fluid (has to be the same factory spec) in a bottle, you can then compare. Doing that would be a good starting point to rule out worn clutch packs or bands.

Edit: Thinking more- unless your transmission slips (does it) it's prob not the clutches/bands. However, if you work your transmission a lot or your miles are higher, checking the fluid could not hurt. I'm thinking its a pressure issue. Could be a leak internally, a bad or somewhat bad pickup, bad pump or pump seal (internal leak).

 

The car is a 2008 with < 30k miles on it. Any pictures of where the transmission bolt is? I used to (about 30 years ago) work at Aamco (think C4/C6/FMX/TH350/TH400 were the current technology), so I know burnt fluid when I smell it, and can certainly identify friction or metal in the fluid (a little on a white napkin and take it to the sunlight). I was told they were a sealed unit so didn't even bother to go look.

no, no slip, and no excessive overlap on the shift. It appears the pressure is at least sufficient to fully apply the clutch packs. And it just the odd-ball time when it seems to 'free-wheel'.

So, I guess the answer is.. no, it's not normal, eh?

 

Talked to the local dealer today, they said if there is no code, they can't diagnose it.

So, next question. Dan anyone point me to pictures and info on how to check fluid level?

Thanks

 

Transmission Fluid Check

This procedure checks both the transmission fluid level, as well as the condition of the fluid itself. Since the transmission on this vehicle is not equipped with a fill tube and dipstick, a tube in the bottom pan is used to set the fluid level.

Caution: The transmission fluid level must be checked when the transmission fluid
temperature (TFT) is between 30-50°C (86-122°F). If the TFT is not within this range, operate the vehicle or allow the fluid to cool as required. Setting the fluid level with a TFT outside this range will result in either an under or over-filled transmission. TFT>50°C=under-filled, TFT<30°C=over-
filled. An under-filled transmission will cause premature component wear or damage. An over-filled transmission will cause fluid to discharge out the vent tube, fluid foaming, or pump cavitation.

1. Observe the TFT using the driver information center (DIC) or a scan tool.
2. Start and idle the engine.
3. Depress the brake pedal and move the shift lever through each gear range. Pause for at least
3 seconds in each range. Move the shift lever back to PARK. Ensure the engine RPM is low
(500-800 RPM).
4. Allow the engine to idle for at least 1 minute.
5. Raise the vehicle on a hoist. The vehicle must be level, with the engine running and the shift lever in the PARK range.


<THIS IS WHERE THE PICTURE OF THE TRANS PAN IS SUPPOSED TO BE>


Caution: THE ENGINE MUST BE RUNNING when the trans oil level check plug is removed or excessive fluid loss will occur, resulting in an under-filled condition. An under-filled transmission will cause premature component wear or damage.

Note: Continue to monitor the TFT. If the TFT is not within the specified values, reinstall the trans oil level check plug and repeat the previous steps.


6. Remove the trans oil level check plug (1) from the transmission fluid pan. Allow any fluid (2)
to drain.
• If the fluid is flowing as a steady stream, wait until the fluid begins to drip.

• If no fluid comes out, add fluid until fluid drips out. Refer to Transmission Fluid Fill
Procedure.
7. Inspect the fluid color. The fluid should be red or dark brown.
• If the fluid color is very dark or black and has a burnt odor, inspect the fluid and inside of the bottom pan for excessive metal particles or other debris. A small amount of "friction" material in the bottom pan is a "normal" condition. If large pieces and/or metal particles are noted in the fluid or bottom pan, flush the oil cooler and cooler lines and overhaul the transmission. If there are no signs of transmission internal damage noted, replace the fluid filter assembly, repair the oil cooler, and flush the cooler lines.
• Fluid that is cloudy or milky or appears to be contaminated with water indicates engine coolant or water contamination. Refer to Engine Coolant/Water in Transmission.

Caution: Refer to Fastener Caution in the Preface section.

8. Replace the trans oil level check plug and tighten to 25 N•m (18 lb ft).
9. Inspect for external leaks. Refer to Fluid Leak Diagnosis.
10. Reset the oil life monitor only if the fluid was changed.