Sluggish Transmission

[L8RH8R]

On my 2004 I have noticed something. In the winter months (I’m in Texas) there seems to be no issue with the transmission. In the summer months, however, I noticed that after the transmission warms up, it is very sluggish when accelerating from a stop. No issues when accelerating at freeway speeds. When nightfall hits, no issues again. I do have a factory installed trans temp gauge in my cluster and it is not running hot. I’m at a loss. Any ideas? A relative (mechanic) thinks it may be the torque converter, and recommended adding an external cooler.

Thank you.

 

[Marky Dissod]

When did you last change your ATF?

 

[L8RH8R]

Interestingly enough, the fluid has been changed out over time. When the vehicle sits for a couple of weeks, it leaks from the tail shaft. If I drive it a few days a week, no leak. I fixed this issue years ago by removing the tail shaft and replacing the bushing and seal but it’s doing it again. So in a nutshell the fluid is not old.

Thank you for the question.

 

[Marky Dissod]

In the winter months (I’m in Texas) there seems to be no issue with the transmission.
In the summer months, however, I noticed that after the transmission warms up, it is very sluggish when accelerating from a stop.
No issues when accelerating at freeway speeds. When nightfall hits, no issues again. I do have a factory installed trans temp gauge in my cluster and it is not running hot.

@NickTransmissions might have an idea ...

 

[NickTransmissions]

On my 2004 I have noticed something. In the winter months (I’m in Texas) there seems to be no issue with the transmission. In the summer months, however, I noticed that after the transmission warms up, it is very sluggish when accelerating from a stop. No issues when accelerating at freeway speeds. When nightfall hits, no issues again. I do have a factory installed trans temp gauge in my cluster and it is not running hot. I’m at a loss. Any ideas? A relative (mechanic) thinks it may be the torque converter, and recommended adding an external cooler.

Thank you.

I am inclined to agree w/your mechanic relative...Sluggish acceleration at take off and lower speeds but no issues at highway speeds is typically the converter's stator one-way clutch failing to hold thus no engine torque multiplication is occurring. As a result, it feels like the engine has been robbed of its power at take off. Fluid is a bit thicker when temps are cooler so a worn stator may present with these symptoms only when ambient temps are on the high side.

i would also add an external cooler - run it in series w/the cooler in the radiator for max heat exchange efficiency.

 

[L8RH8R]

Thank you very much for the reply. I’m gonna try both.

 

[L8RH8R]

I replaced the torque converter with an AC Delco unit ($$$). Night and day difference. Once the trans cooler gets here I should have many miles of trouble free driving. Thanks to everyone one who commented.

 

[L8RH8R]

Just another update. I added the Mishimoto trans cooler and replaced the fan clutch. Huge difference on the first drive. I looked at both the Tru Cool and Mishimoto and read a lot of reviews. The Mishimoto is about three times the cost, but wow, what a great looking and feeling unit. I also liked the fact that it was a direct fit and the lines hooked up like the old unit. Just my .02. Thanks again for all the input.