Blackxltlariat

Hey all! I'm a new guy. Here's the deal. I bought a 91 f150 xlt lariat. 5.0 302. 110k miles. Automatic trans. When cruising a any speed there is a rumble type sound that comes in when I put a little load on the engine. Example: cruising on the highway at 60 miles an hour on flat road. If I add just a little pressure to the gas, this rumbling begins. If I release the pressure, it goes away. Same thing happens if the road has a little uphill incline. This also happens when cruising in town at say 35 mph. The tranny seems to shift gears fine. My thoughts are leaning toward the torque converter. Also, I've heard it's not good to do a tranny fluid flush on older cars. Is this true?

Any info is greatly appreciated

Thanks

BLDTruth

Sounds like it might be time for new u-joints.

Blackxltlariat

I did replace the rear u joint because it was a little sloppy. Front u joint seemed solid so I did not replace it. Made no difference as far as the symptom I described

Crownman

Check to see if the motor mounts are collapsed. If they're broken or just worn out the driveers side could be lifting up and hitting something under load, or the passenger side could be compressing and letting the engine or exhaust hit something while under load.

Also, if you have a center bearing on the drive shaft that could be going out.

Sauce06

I know its an older thread....Did you ever find the problem?