Stumped two mechanics with popping in truck

**LisaO925** · 05-08-2009, 01:49 AM

95 GMC Sierra 2wd 2500 used to be a truck for pulling horse trailers. Then I retired it when I got out of horses, and now use it as a daily driver 180k miles on it.

Has always been maintained perfectly. Within the last 3 months or so, I started to hear a popping while driving. I just assumed it was when I turned, so figured the ball joints needed replaced. Didnt have the money at the time, so I greased them. Still popped. Took it to a Les Schwab last weekend because of nail in tire. Mentioned the popping, they said that I needed a new Pitman Arm and Idler arm. Got it done today. When I went to pick it up, and paid the $325, I asked, "So, no more popping right??" He said that was my problem, and that everything else was tight and fine. Half way home, it started popping again

. So, I called, and they said to come back down. We took it for a test drive, and really listened to when it made the popping sound...

*Accelerating from going under 5mph, but still rolling. It does pop when turning to a slight left, but not tight left.

*Accelerating in reverse

*Going into my driveway, which has a low grade slope, or any low grade slope - both directions

**Does NOT pop going over speed bumps

**Does NOT pop turning as in a U turn or a tight turn

The popping actually sounds like its from the back of my truck. 45 minutes later, they still could NOT figure out what was causing the sound.

Another guy took it for a test drive, and he couldnt figgure it out.

They promised me its not any bushings, no frame damage, or the bed hitting the cab or anything.

Can anyone here tell me what it might be. Its really annoying! Its gotta mean there is a problem somewhere, and I want it fixed before something bad happens.

**heavy chevy** · 05-08-2009, 02:16 AM

Sounds like it is a wheel barring or a u joint take it to another place maby a local mom and pop place. They will get it fixed for you . I never take my stuff to a big branch. They will find the most expensive part and replace it. If it dont work they go to the next most expensive part. Mom an pops places usually will do you rite the first time. Good luck and let me know what you find out.

**Z71_guy** · 05-08-2009, 01:02 PM

sound like a u joint binding

**vncj96** · 05-08-2009, 01:04 PM

Sound like u joints but do you have a locker in it? That pop could be the locker engaging or just not functioning correctly.

**Jimmiee** · 05-08-2009, 03:05 PM

Sounds like a wheel bearing from the symptoms. Have you ever packed your wheel bearings?

**Blazerado** · 05-08-2009, 08:14 PM

Check the sway bar bushings by turning the wheel with it in park. If that doesnt work than try spraying the sway bar bushings down with some grease and then drive it. Hope you figure it out, we get a lot of 2500-3500 trucks and SUV's with this problem and noise. It isnt easy to pin point if you dont know. lol

**Blazerado** · 05-12-2009, 05:48 PM

Originally Posted by LisaO925

95 GMC Sierra 2wd 2500 used to be a truck for pulling horse trailers. Then I retired it when I got out of horses, and now use it as a daily driver 180k miles on it.

Has always been maintained perfectly. Within the last 3 months or so, I started to hear a popping while driving. I just assumed it was when I turned, so figured the ball joints needed replaced. Didnt have the money at the time, so I greased them. Still popped. Took it to a Les Schwab last weekend because of nail in tire. Mentioned the popping, they said that I needed a new Pitman Arm and Idler arm. Got it done today. When I went to pick it up, and paid the $325, I asked, "So, no more popping right??" He said that was my problem, and that everything else was tight and fine. Half way home, it started popping again

. So, I called, and they said to come back down. We took it for a test drive, and really listened to when it made the popping sound...

*Accelerating from going under 5mph, but still rolling. It does pop when turning to a slight left, but not tight left.

*Accelerating in reverse

*Going into my driveway, which has a low grade slope, or any low grade slope - both directions

**Does NOT pop going over speed bumps

**Does NOT pop turning as in a U turn or a tight turn

The popping actually sounds like its from the back of my truck. 45 minutes later, they still could NOT figure out what was causing the sound.

Another guy took it for a test drive, and he couldnt figgure it out.

They promised me its not any bushings, no frame damage, or the bed hitting the cab or anything.

Can anyone here tell me what it might be. Its really annoying! Its gotta mean there is a problem somewhere, and I want it fixed before something bad happens.

Hey just wondering if there is any news on a fix?

**LisaO925** · 05-18-2009, 11:33 AM

Funny you should ask. I finally decided last night to take it to a mechanic this AM to get looked at. I sware to you that the whole time from start up, to taking kids to school, and coming back home, I did not hear one single pop. So, I passed on the mechanic for now. Plus when I drove by they looked real busy and this is my only vehicle for right now.

So, I am NOT sure if I should be more nervous that I dont hear the sound anymore, or feel better. Honestly, I think it freaks me out more..lol

**navyCM** · 05-19-2009, 10:14 AM

from what you described a "popping" and the location of sound "rear of truck" and the nature of what you used it for "towing horse trailers". thats a u-joint going out. get under your truck if you can near the rearend where the driveline goes in and twist the driveshaft and see if the u-joint moves. it should stay put and the driveshaft should twist slightly into the rear, but the u-joint should not move in the yoke.