Newbie with a problem

[ronb1023]

Hello everyone. I have spent a couple hours browsing through the many posts and I am very impressed with the knowledge of the members of this site. I havent found a previous thread that addresses my particular problem.
Heres is my problem. I recently purchased a 02 X EB and have to say I LOVE it! The look, the ride, I love everything about it...EXCEPT.....
I recently noticed a "knocking" or "thudding" when starting from a dead stop. There is no noise associated with it, just a thudding that I can feel. After I get rolling, it runs and drives great. It seems to be worse after a long freeway drive.
Any ideas? After reading about all the tranny problems and expensive repairs associated with them, I am a little nervous.
Any advice would be greatly appreciated!!

 

[manaen]

do you have 4wd or AWD? and which engine?

have you checked the tranny fluid for level, color, and burnt smell?

 

[ronb1023]

I have the 4.6l V8 4WD. I havent checked the tranny fluid level or condition yet. There is no dipstick, so I have to get under it. I am going to do that this afternoon.

 

[manaen]

I have the 4.6l V8 4WD. I havent checked the tranny fluid level or condition yet. There is no dipstick, so I have to get under it. I am going to do that this afternoon.

Ah yes of course, you have the dip stickless 5r55w. If I remember correctly your year has AWD, 4WD, 4LO on the selector. I'm wondering if this is a 4wd /awd related issue.

FYI the 5r55w is much stronger than the predicessors, maybe not as strong as the 4r70w. but you've got a pretty good tranny as long as you take care of it and get the fluids changed at normal intervals.

What mileage do you have on your truck?

 

[ronb1023]

The selector has buttons for 4x4 auto, 4x4 Hi, and 4x4 Lo. Unfortunantly, I cant just turn off the 4 wheel drive system. When the car is cool, there is no clunck at all. After a longer drive, the "clunk" is always there. Other than the problem when I first begin to accelerate, the tranny seems strong.
I am confused!!

 

[manaen]

well when the 4x4 auto system engages there is a slight clunk feeling in mine. Although it should only engage when the rear wheels slip. This condition is determined by the speed sensors on the wheels. Do you have any lights on (ABS, CEL, OD) indicating a stored code?

 

[High_Order1]

hm

Just throwing this out there, but it could be a U joint, too. GM products have a problem with the front shaft that drives the front axle that sounds the same. Lack of lubrication causes that one.

I would definately try to find it before it fell out, though. Have you thought about putting all four wheels up on jackstands, and rotating each wheel to see if you can narrow it down?


-Shawn

 

[ronb1023]

There are no lights on on the dash to indicate a computer code has been triggered. By the way, you asked about milage and I forgot to respond. My X has about 75,000 on it.
I just took a trip about 90 miles away. when I left, there was no problem at all. But only after I drove for a while did the "noise" happen again. If it was a U joint, I would think the problem would be there all the time, not just after it warms up. I was pretty bad after the drive. Sound like maybe tranny or rear diff?

 

[Thelt]

I would change the fluid in the transmission and service the rear differential. It may not cure the problem but you probably need those things done anyway.