OK guys, here's the deal.

I have a 1995 F-250, 5.8 351 4X4, 173,000 miles, still has the original tranny (stickshift).

This truck, other than this one problem which is probably due to old age as much as anything, has been the prototypical Ford. It takes a beating in a harsh climate, and still runs almost like new. I/we have owned it since it was new and have been meticulous in maintaining it.

About two years ago, at around 130-140,000 miles, the clutch went out and had to be replaced. The mechanics who replaced it were a bunch of incompetent *****, as nearly as I can tell. After they replaced it, the truck began making a rumbling noise, sounding like a little bit of metal rubbing against each itself. This happens only above 70 mph, and is considerably worse going downhill.

Last winter I replaced the slave cylinder and the noise got better, but was not cured. Basically, on a flat straightaway above 70 it does it a fair amount. Going uphill at 70 it hardly does it at all, and going downhill it does it A LOT. The noise comes from the vicinity of the transmission/transfer case.

I've thought it could be the tires, but I can't see how tires would be making a metallic sound. Another thought I've had is a loose mount is causing the vibration (perhaps the transmission mount?). Or perhaps something is going on with the transfer case/four wheel drive. It has auto hubs on it, but the 4X4 does not seem to be malfunctioning in any way. Or maybe the transmission is just getting old and wants to be replaced, which is entirely possible. However, the gears don't grind and it still shifts like it is brand new. Or maybe they just gave us a faulty clutch.

So, for those of you who read all of that, what are your ideas? Like I said, this has been going on for a couple years and it still hasn't broken down so I'm inclined to think it's not overly damaging to the truck. But now that I have a little bit of cash in the bank I'd like to try and fix it so I can get back to smokin' chevy's on the highway.

Any help is appreciated. Thanks in advance.

 

Well I'm no drivetrain buff, but it's sounding to me like your differencial is causing the problem somehow. Another thought is the torque converter.

Just a total guess, but without seeing the truck, that's what it sounds like to me.

 

Check the driveshaft u joints too. Mine had a hi speed vibration for quite awhile before it got really obvious.

 

Thanks for the ideas. I had actually considered the torque converter. Anybody else?

 

Unless they've really changed things in the newer trucks, manual transmissions don't have a torque converter. That's what the clutch is for.

 

well if it is a manual transmission like stated at the top of the page it doesn't have a torque converter the only torque converter it has is the clutch. It could be the throw out bearing they make alot of noise and vibration when they start going bad.

 

I just thought of another source of the problem. If the drive shafts aren't balanced they will cause vibration.

 

I had a problem like yours for amost three years only it would happen at any speed. It would leave if I have it more gas, or let up on the gas. After checking all the big stuff. It turned out to be a vacum problem. Cost me $5.00 to fix. The line is located right in the front of the truck. Open hood look to the left There will be a hose going into a plastic container.(not the tin can) One hose goes to the top of the egine the other goes to the transmission. Mine was the top hose. The only way I found it was when it broke off. This was on a 93 auto in line six. I hope you get as lucky as I did. Good luck

 

Sounds like either the oil pump in the tcase spun free from it's shaft and grinding the side of the case or the chain is overly stretched out and hitting the case. I had a loud growl from my truck that didn't go away when i swapped transmissions (thought is it was the mazda letting go again). Ended up being a worn tcase.