In 2WD (I've not tried it in 4WD), my truck makes a howling sound between 40 to 45 MPH. It's kind of loud and it reminds me of the same kind of sound that my old Tempo made when the front wheel bearing went out of it.

I took it to my mechanic friend, and he says that it's not wheel bearings. He took the truck up to the speed that the noise happened and began weaving the truck down the road. He says that this will "load" the wheel bearings and if it's a bearing, that the sound should change, and it doesn't when he did this test. He thinks it's driveline, but isn't sure where we should go from here.

I talked to the guy at our truck shop, and he thinks it might be a u-joint, but I seem to recall having looked at my u-joints on the back driveshaft (they're all new up front!), and they seemed to be good, but I do know that my rear diff has some play in it. It does clunk going into drive or reverse. That being said, if it's the diff, shouldn't the howl start right away, and get louder the faster you go, never dissapearing at any speed?

My truck is a 1988 F-150 XLT Lariat 4X4 with a C6 auto transmission and 351 V8. Limited Slip Diff.

Anyone have any suggestions or ideas?

 

usually a clunk when going into drive or reverse is the sign of a bad ujoint




Jim

 

check rear axle bearings

 

my friend had that noise and it turned out to be a pinion bearing, (it was a dodge.)

 

sounds to me like gear lash. change the gear oil in the rear end to a heavyer oil