Hey guys, first post here, hoping I can get a second or third or fifth opinion. I have a 67 econoline supervan, and have been getting a grinding noise out of the rear end at certain rpm’s. It’s only under heavy load, when I’m first accelerating, that the noise comes out. Now here’s the question, is this the wheel bearings just screaming for attention, or my rear differential in dire need of help? Now, the only thing I’ve done so far to remedy it is change the differential oil, to no avail. Any ideas?
Your differential is probably well worn and starting to disintegrate at this time. If you had changed the fluid every 40,000 miles since new, you probably would not have the problem. How many miles on the truck now?
IF it was your Rear Diff…Methinks you would ALWAYS hear the sound…sounds from a diff usually do not subside until the vehicle is stationary. You mentioned it does this only at certain RPM’s and under heavy load. My first thought was the U joints in the driveshaft groaning under strain and too much slop in the joint. I would first inspect the U joints in the driveshaft…THEN…check to see that you have sufficient lube in the rear Diff. After this…you might be describing some kind of noise emanating from one of the rear Brake Drums…A small spring or a clip may be bouncing around inside one of the rear Brake Drums…
Any one of the things I mentioned would make some kind of noise. Im fairly confident that a noise from the Rear Diff would really never subside…it should be present whenever in motion.
The u Joints have the ability to make noise and then subside and then return etc…The Diff usually will make a constant noise that will never subside. I am leaning HEAVILY TOWARD THE U JOINTS IN YOUR DRIVESHAFT… Easy enough to check them… there should be AT LEAST TWO of them…could be as many as 4 if the shaft is long enough.
Blackbird, I thought the same thing that the noise would be more constant if the diff were worn out. I will definitely look into the U-joints, and i appreciate your input!
How did the fluid in the rear diff look? How much debris in the bottom of the housing? Ujoints and bearings require the next looksie. Can you observe slack in the ujoints by playing with the drive shaft, when not running of course. Bearings in my experience are usually a constant, like driving with snow tires.
The 1967 Econoline was basically a shoe box built around a Falcon drive train and there was virtually no sound deadening under the truck. In fact the engine is between the seats in a removable dog house that by now has lost all the horse hair padding and aluminum foil fire proofing. I drove a few of them years ago and it was not fun above 45 mph. And if the noise is troubling it will require opening the rear end for inspection. BTW, with the transmission in neutral you might grab the output shaft and push it up and down, side to side and if there is any play the noise might be originating there.
When I changed the rear diff fluid the stuff was ugly. Sludge ugly. But, this could be attributed to the fact it sat in a barn in Rhode Island for 25-30 years. I only drove it probably 100 miles before changing it, and upon visual inspection, the teeth of the gears looked ok to me (but granted, I’ve never looked at a new differential to use as a mental benchmark.). I will go out there and play with my shaft…there’s a joke here…tomorrow and let you guys know what I find. As for the general road noise, Knox, yeah it’s loud, but it’s this more shrill, higher pitched grinding that sometimes cuts through all the noises you would normally expect from a vehicle akin to a b-52 that just happens to never leave the ground.
If the noise is louder in 1st and 2nd gear the problem may be the transmission center bearing. Usually the transmission will jump out of 2nd and 3d gear when that bearing is failing though. I’m guessing you have a standard transmission. But a B-52 that won’t leave the ground makes me suspect it is a poor gear mesh in the transmission or rear end.
A little update for those who care for some reason; barkydog, you nailed it! Felt a ton of wiggle in the shaft, so I replaced the U joints yesterday. Today on my hour commute to work, I didn’t hear that grinding noise once, and I was hammering on the gas, trying to get it! I’m still going to go ahead and re-clean the diff, make a thorough visual inspection, and change the bearings. Thank you to everyone for the input.
Ummm Uh HUM HUM (Throat Clearing Sounds) COUGH COUGH… WHO NAILED IT?? LOL
Happy you found the issue…we are a pretty good Brain Trust out here. No need for a Cookie or a Cape although I’ve Admired Batmans Cape since I was a young Boy… So maybe I’d like a Black Cape…LOL
HAHAHAA. Yeah those U-Joints…people think they last forever until they Pole Vault the Vehicle down the Highway as their driveshafts let loose… They even have grease fittings that people ignore.
Yeah, I made sure to pack those suckers, and even pushed out all the old grease from the shaft out. When I took the old u joints out, a ton of the little rollers just scattered out of the ends when I pulled them off. Obviously a bad formula for a smooth ride.