Another "pop" issue in front end
Postmaster
Joined: Apr 2001
Posts: 3,818
Likes: 3
Almost right. On a turn the inner and outer wheels turn at different speeds but the differential compensates for this. End result is no effect on the driveshaft itself - its always "neutral" to what's happening elsewhere. Your point about the transfer case solenoid is valid and could elicit this problem. When I first had my van I had similar issues when pulling into or out of a parking space. Occasionally, I would get a severe "bang" (or loud pop as the case may be) noise and tire scrubbing. Since it was under warranty I took it in and the dealer replaced the front half shafts. It was okay for about 9 months then it started again on rare occasions and finally just stopped altogether. I haven't had any for the last 10 years and yet I know the transfer case solenoid still works. I get to test it every winter when it snows. At the time mine was acting up, this forum didn't exist and I did not know about disconnecting the electronics under the driver's seat. You state you did disconnect yours and this still happens. To me, that would rule out the transfer case and solenoid.
You have an interesting problem althought I'm sure you don't view it that way. Keep up posted on what you find.
You have an interesting problem althought I'm sure you don't view it that way. Keep up posted on what you find.
Thread Starter
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Senior User
Joined: Dec 2001
Posts: 107
Likes: 0
If the van had four wheel steering, I'd agree about the driveshafts. Fact is, the front and rear turning raduis with a fixed rear axle is NOT the same. Despite the differential (which in this case averages the wheel rotation), the shafts will turn at slightly different rates. If this was not the case, a bad transfer case sensor (which simply measures shaft rates) wouldn't cause a pop... if everthing is "neutral" to use your description... in a turn. The van electronics wouldn't react differently in a turn in stead of straight ahead... but they do.
Yep, its a puzzle. I'll keep chasing it. I'm pretty convinced its powertrain related and that the axles are being loaded up and then released... causing the pop. I've also noted the 8mm bolts that hold the half shafts to the front differential keep loosening up on the driver's side...
KenP
Yep, its a puzzle. I'll keep chasing it. I'm pretty convinced its powertrain related and that the axles are being loaded up and then released... causing the pop. I've also noted the 8mm bolts that hold the half shafts to the front differential keep loosening up on the driver's side...
KenP
Freshman User
Joined: Jul 2003
Posts: 31
Likes: 0
Mystery Continued...
My 91 E4WD has the same "POP", I wanted to revise the thread just incase the problem was found.
I did pretty much the same as everyone else, I have not replaced the upper control arm bushing. They don't look bad.
Thanks,
I did pretty much the same as everyone else, I have not replaced the upper control arm bushing. They don't look bad.
Thanks,
Elder User
Joined: Dec 2006
Posts: 830
Likes: 0
From: Kitchener,Ontario,Canada
Originally Posted by kenp
Hi. Chasing a "pop" in my front end and would like to get some opinions, because I'm about at the end of my wits!
Van is '96 Aero AWD with 125K miles. Pop only occurs when backing up with the steering turned to one side... it will roll about 10 ft and then POP. Sounds like left side, but hard to tell because its so loud. I can feel it in the floorboard of the van right under my feet. When I turn the wheel the other way (as in backing out of a parking space and then moving forward) it will POP again... just once. Other than that, its perfect.
So far, I've replaced lower control arm, drivers side. Upper ball joints both sides. Upper control arm bushings drivers side. Sway bar bushings, front. Front shocks. Both front axles. Front diff mountings. and it still POPs.
Its definitely not the transfer case sensors. Only pops once going backwards (like something is moving or twisting) with the wheels turned hard over and only once when going forward again (like its popping back into position).
Everything is tight. Cannot make it pop any other way.
Ideas? I'm thinking front drive shaft joints or transfer case chain.
Thanks for any ideas.
KenP
Van is '96 Aero AWD with 125K miles. Pop only occurs when backing up with the steering turned to one side... it will roll about 10 ft and then POP. Sounds like left side, but hard to tell because its so loud. I can feel it in the floorboard of the van right under my feet. When I turn the wheel the other way (as in backing out of a parking space and then moving forward) it will POP again... just once. Other than that, its perfect.
So far, I've replaced lower control arm, drivers side. Upper ball joints both sides. Upper control arm bushings drivers side. Sway bar bushings, front. Front shocks. Both front axles. Front diff mountings. and it still POPs.
Its definitely not the transfer case sensors. Only pops once going backwards (like something is moving or twisting) with the wheels turned hard over and only once when going forward again (like its popping back into position).
Everything is tight. Cannot make it pop any other way.
Ideas? I'm thinking front drive shaft joints or transfer case chain.
Thanks for any ideas.
KenP
Might be a long shot but what about your engine mounts or centre transmission mounting block ? When you change drive direction the torque on the drive shaft is reversed & the transmission tries to lift or hang depending upon resultant torque direction. It could be that you have a failed rubber block & this makes a poping noise as it puls the bolt out of the rubber block? (dont know for sure but it sounds feasible)!
Worth a look,
Aeroman
Mountain Pass
Joined: Oct 2002
Posts: 205
Likes: 0
From: Jaqcksonville
Popping
I had a popping sound and found that the bolts attatching the upper control arms....the ones that keep the alignment shims tight had become loose. I had the van aligned 3 yrs ago and as you know its a tight spot to get a wrench in there to tighten them up good.
Senior User
Joined: Apr 2004
Posts: 312
Likes: 0
From: Lanham,MD
Yeah I too have the AWD pop. Im about to replace the upper control arm bushing since one fell out recently. My pop sound is worse with the arm shifting around. I hope someone founds the solution while I have the front end apart.
Lead Driver
Joined: Sep 2003
Posts: 7,015
Likes: 208
From: SoCal
Is this the same "pop" that occurs when the transfer case locks up from incorrectly functioning control module? Does it only occur at low speed turns? Try disconnecting the control module under the driver's seat to see if it stops. If so, you may have a speed sensor problem.
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