My truck has been making a VERY intermitent (sp?) noise that appers to come from under the truck at highway speeds (65-up).

The first time it did it I was on the highway for less than 10 minutes , it sounded kind of like there was something banging around under the truck. I turned off the radio , put the tranny in N and revved the engine....it was not engine related , as it didn`t speed up with the RPMs , but did go away after I got under 50mph.

I drove to my mech. friends place , and couldn`t get it to do it again (isn`t that ALWAYS the way).

Fast forward 3 weeks later , to this past weekend....I took a trip to Gainesville (about 3 1/2 hrs) and had the cruise set at 67 the entire way with NO noises. Drove another 200 miles while I was there , again NO problems.
On the way home we were stopping in Ocala , running 75 or so,(1 hr drive from where we were), and just about the time we were going to get off the interstate , the noise came back...scared the heck out of the kids. I really wish I had a better way of explaining the noise to you guys , the kids thought it sounded like we were going over a set of railroad tracks...I though it sounded like the driveshaft had come loose and was banging around.

Once we got off the highway , it went away. We went to the waterpark for a few hours , and continued the drive home...this time at 60 mph....(man were we ever getting blown off the road by everone)and had no more noises. About 25 minutes from home I got back up to 70-80 to see if it would do it again closer to home , but no luck.

The lift has been on the truck for several years with no problems (it only has a 3in. block in the rear) , but I`m just wondering if the u-joints are getting ready to go. Everything under the truck seems tight.

Sorry for the long post , but I`m at a loss as to what it could be , as it doesn`t do it all the time.

Any ideas?

 

Get the truck in the air with jack stands , get a large screw driver to pry with , as you turn the front wheels by hand , stick the screw driver in on each of the 4 joint cups & try to pry a little , should not be lose , also watch closely for brown rust stains around seals to bearing cups .
Then go to ft. drive shaft , use pry bar to turn drive shaft & wiggle yokes at u-joints , while watching & fealing for looseness , then back the r. drive shaft .
As long as its in the air , grab the top & bottom of ft. wheel and alternately push & pull on the top & bottom , should not be lose or clunk - clunk .
Then gab the wheel front & rear & wiggle , should not find lose , if so have some one go to each of the steering parts , while someone is wiggling the wheel , to look for lose parts .
Then to the rear wheels , wiggle to see if bearings are lose .

 

I`ll check those things out...thanks.

Would the u-joints (or anything else really) make a noise ALL of the time , or could it be just sometimes?

 

Sounds more like a wheel bearing to me. I've seen bearings that had no play in them what so ever, and made no noise, except for at certain speeds. U-joints will also make noise though, so like John said, make sure they are tight and no rust around them.
Good luck. Noises are fun to find.

 

Thanks guys...I`ll have them checked too.

The worst part of the whole thing is being scared to drive the truck too far away from home and getting standed (again!). Suckss to have a 40K dollar truck you can`t trust.