2001 yukon smoking at highway speeds

[94_3.4]

hey, i have a 2001 yukon slt with the 5.3 (i think) and i have noticed at least 3 times in the past 2 years that it starts smoking really bad for a few minutes at highway speeds (60+) it only smokes for a few seconds, and stops as soon as i let off the gas. i have explained this problem to the dealer, but they can do nothing unless we replicate the problem and it has only happened 3 times in 2 years! despite the rarity of this, i dont like the fact that my car is smoking!! please help me so i can get this fixed! thanks ahead of time

[GMMerlin]

Originally Posted by 94_3.4

hey, i have a 2001 yukon slt with the 5.3 (i think) and i have noticed at least 3 times in the past 2 years that it starts smoking really bad for a few minutes at highway speeds (60+) it only smokes for a few seconds, and stops as soon as i let off the gas. i have explained this problem to the dealer, but they can do nothing unless we replicate the problem and it has only happened 3 times in 2 years! despite the rarity of this, i dont like the fact that my car is smoking!! please help me so i can get this fixed! thanks ahead of time

Unfortunately unless you can duplicate the concern, it will be difficult to diagnose what the root cause could be.
Can you tell us at least what color the smoke is..this could give some clues to the system that may be the cause

[94_3.4]

sorry i cant remember what color it was, the last time it happened was a few days ago, but i wasnt present at the time. (my dad took it to work) i forgot to mention that the smoke is not coming from the exhaust, but rather towards the front/middle of the car. after getting under the car, i learned that the exhaust pipe runs right under the transsmission pan. i believe either engine oil or transmission fluid is spilling onto the hot exhaust, making the smoke. only problem is that neither fluid level drops noticeably, and the transmission gasket has been replaced twice (along with the fluid and filter). also all of the fluid is burned up by the time i have a chance to stop so i cant identify it, and neither fluid leaks at idle. its like the fluid squirts out in a short burst and then stops. it happens very rarely, and will stop on its own in a few seconds even if i dont let off the gas. by the way, the engine has just over 190,000 miles. thanks!

[GMMerlin]

The transmission has an overflow tube. Quite possibly, the trans is overheating and burping fluid onto the exhaust.
There was a TSB or Tech assist that came out years ago about extending the tube with a rubber hose to direct the fluid away from the exhaust