nilknarf007

Yes sir, I now have grease fittings! I will also continue my lifetime streak of never driving on pavement in 4WD.

First off, thank you to everyone that offered suggestions. Today was the first time I was able to get the truck on a lift so I could put it in gear and let the wheels turn. I'm going to be honest, I poo-poo-ed the U-joint problem because I had already checked everything thing in the drive train and the suspension for play. There was none, so I moved on trying to find a different solution. However, getting the truck on a lift taught me that the front drive shaft is like a giant wind chime - any noise connected to it amplifies the noise and makes it hard to track down. Out of frustration, I removed the drive shaft and made a discovery that I'm sure all of you will laugh at, but was a first time for me. Bad u-joints don't always have play in them. Sometime they just seize. That's what mine did. Replaced, and running fine. Maybe next time I'll listen a little better. Thanks again!

Can't get it to go into low, but I can't get under it enough to see if there is an obvious problem with that. It's a fixed yoke. I guess I need to find a lift so I can see under it.

Nope. Stays the same. But I haven't driven it over about 10 MPH in 4wd due to the vibration. Don't know if it goes away at speed, but I doubt it based on what I'm feeling.

ArdWrknTrk, the rubber you mentioned has seen better days. I'll have to look into once I can spend some time underneath while dry. There is no slop that I can feel. There is no play front to back, side to side, or rotationally. Oh, and I can rotate the front drive shaft with my hand while in neutral and unlocked. It's not easy, but I can rotate it. I changed the front diff fluid when I bought the truck a little over 2 years ago.

Thanks Gary. I gave that a shot, and I got the vibration with both sides. Keep in mind though, I'm really going slow. The drive shaft to the front end is in really good shape. Not going fast enough for a u-joint problem to rear its head unless something was missing from it. I'm afraid if I go faster than idling in 1st gear (actually 2nd), something will fly apart. As far as switching the truck into 4wd, I'm familiar with how to do that. Plus, there isn't any dry pavement for miles. We're in the middle of a good snow. I did notice, however, that my 4wd shift lever doesn't have the positive "detents" that it used to. They're still there, but not as pronounced as it used to be.

1985 F150 4x4 with 4.9 and NP 435 manual transmission. When I lock the hubs, I get a vibration that is proportional in speed with the rolling of the tires. No movement, no vibration. Even vibrates when still in 2wd with hubs locked. Checked the U-joints and all related mounts, and can't find a problem. It's so bad, I've only gone about 8-10 mph in 4wd. Anyone have any ideas? nilknarf007 1985 F150 4.9 IL6 NP435 4x4

That would probably be a lifter. It goes away when it warms up. I just rebuilt the transmission about a month and a half ago, so all that clutch stuff is brand new.

I have to admit, I thought all you guys were nuts. There was no way a vacuum leak could cause that kind of noise. But, I did the smoke test, and I had a small leak into the intake manifold from the brake booster, and major leaks from the intake. I tightened everything up, or I should say I'm in the process of tightening everything up, and the noise has almost completely gone away. That aftermarket Clifford intake is a beast to get in the right place. Plus, the tabs are off just enough that in a few places, I've had to fashion bigger washers so that the bolts will grab the intake and exhaust. But the bottom line is: You guys were right. Vacuum leak. I feel so blessed to have such a great resource as this forum. You guys are the best.

Haven't drained the oil. That will be the next thing I check. I just have a stock oil pressure gage, and it is showing good oil pressure. I don't really have any reason to think it wrong. I assume my timing gear is the fiber-composite gear and not the metal one because it's not an industrial engine. I guess it could have something to do with that. Rolling the motor over by hand - I do feel something odd. It's not resistance really, but it is an odd feeling. And, I hear what could become a scream at 1000 rpm. It's not a squeak, but it definitely something out of the ordinary. I haven't had any piston slap, but possibly mild rod knock? It always went away when it got close to operating temperature, so I probably have to adjust the rocker arms. But this problem doesn't appear to have anything to do with that.

Here is a link to a video I shot that will give you an idea about the noise.

Will post a video tomorrow. I did a transmission rebuild about a month ago, but it has been running fine. I had someone crank the engine so I could see and hear what was going on. Definitely in the front of the engine. Transmission in neutral. I won't attempt to drive it with that noise. Definitely afraid to run it long enough to get it up to temperature.

The only thing I've done recently is replace the intake/exhaust gasket. Didn't touch anything else, and checked to see if I messed up anything with the PCV - nope, everything is just as it was before.

Good oil pressure. I'm just confused how something could go south that quick with no symptoms. Drove it all day yesterday, and as usual, never got the motor above 2500. It's not like I hot rod the thing.

Removed all the belts. Still Screaming. Guess it's worse than a water pump.