Help: Driveline thump

[rnb65]

I've searched through a lost of posts about various thumps, clunks, and bumps from the front end, but I haven't found one that really matches what I have. Hopefully, someone can help.

I have a 95 XLT Explorer with 160,000 miles. Over the past few months it's picked up a loud thump that sounds like someone standing underneath and smacking the floorboard with a heavy rubber strip. It sounds like it's coming from the front half of the vehicle. It's worse on cold mornings than warm mornings, but overall it's getting progressively worse. It's a loud, rhythmic THUMP, THUMP, THUMP that gets louder with acceleration and continues when coasting to a stop at intersections. The thumps are very solid and each one sends a shutter through the vehicle that can be felt. It goes away after I've driven a few miles and once it's gone, it's going for good until the vehicle cools down. However, sometimes when I'm braking, there will be a single loud THUMP and I can feel a slight vibration in the brake pedal. Direction of travel (straight or turning) doesn't seem to matter.

Any ideas what the problem is?

Thanks.

 

[rwenzing]

I would check the torque on the caliper anchor plate bolts. They can loosen and eventually fall out if not properly torqued to 85 lb-ft. Undertorquing the anchor bolts is a common error during brake jobs.

If it's 4WD, I would also check the front halfshafts for damage or wear.

 

[Rottie]

I'd also get the tires checked out.

 

[rnb65]

I took it to my favorite repair shop today for state inspection and asked if they could try to chase down the thumping. They were able to generate the thump by driving the Explorer after it cooled down, but they could not locate the cause. They checked all the drivetrain and front suspension components and found no smoking gun. Argh!

The thumping is at it's worst first thing in the morning after sitting overnight. The suggested that I bring it back next week and leave it overnight so they can drive it first thing in the morning. I'll give them one more chance, then I suppose I'll have to take it to a Ford dealership and pay the big bucks.

 

[maxcr3]

I had same problem

I had the same noise on my 99 explorer 161,000 miles. I spent a lot of time and money tracking it. I would start with changing the transfer case oil. The clutches could be the problem. After drive shafts, spider gears, axles, changing the transfer case fluid fixed the problem. I heard the noise decrease with the fluid change. By four weeks the noise was completing gone. I used Amsoil oil.

 

[xdviper]

there has to do something with the torque converter or the transmission.
Did your OD light ever keep blinking?

 

[rnb65]

Did your OD light ever keep blinking?

No. Everything appears to be operating normally. The only oddity is the thumping and the occasional vibration through the break pedal.

 

[Mic_]

update

ANy luck in chasing down your sound?

 

[Redneck0907]

bump!

 

[ZBlackBeast]

If the noise was being generated at steady intervals through acceleration and deceleration, i would think anything with the drive line can be ruled out.. considering it would be very hard to keep an even space at 35 mph as at 10 mph... i would check the brake bolt to.. thats all i can think of... but changing fluids never hurt anyone, so its a chance.