First you can't lube these, they are all "sealed bearings" meaning they are lubed and sealed from the factory. All you can do is replace them.

As for the alternator bearing they tend to not grind or anything until they get to a certain RPM. Then it is weird but they kind of spin in the case at one steady speed even if you rev it up and down.

Took me awhile to figure out what was up with mine the first time because of this. It was not increasing or decreasing with the RPM's like it should. Just one steady grind over a certain RPM. It's kind of strange. lol

 

So if it is the alternator or a bearing wouldn't the sound happen when I'm parked, in neutral, revving the engine? Because it only happens when I'm driving I'm starting to think it's a wheel bearing thing but it's much louder than those have ever been in my experience.

 

Not necessarily, you’re putting more load on the belt. In my Chevy 1500 work van. If you lay on gas, like getting on the highway, the belt squeaks. Probably should get that looked at. Lol

Edit: I guess technically it should happen when you rev the engine though.

 

You might want to pull the distributor cap and check for shaft wobble from the bearing going bad. Look at the inside of the cap for any uneven wear marks.

 

I was going by how this is worded...

"Squeaky, scratching sound coming from engine bay when engine is cold"

And this...

"So this just recently started happening once it started to get cold. There's a scratching yet squeaky sound that comes from the engine bay when I hit around 35 miles an hour. It stops when the engine warms up enough. This sound is loud too. If I have my window down I can hear the sound get bounced off anything I pass very clearly. The sound doesn't increase or decrease with speed it just starts squeaking at 35 and stops when I get below that again.

I have a manual 96 XJ 4.0L"

 

Alright so I jacked one tire in the air and spun it to find the source of the squeaking. Seems to be coming from the output of the transfer case. And it is LOUD. It no longer stops when the engine is warmed up. Just goes all the time.

What do you guys think? Will swapping out the fluid help at all or am I looking at a rebuild?

 

Chain could have slack in it and is dragging on the case. You won’t know until you crack the case open.

 

I'm glad he finally pinpointed the actual source...

 

I'll be getting a rebuild kit and replacing all the things in there soonish. I'll update to let y'all know if that fixed the issue

 

Copy that, good luck!

 

It could be the double joint in your front driveshaft. Mine does the same when it's cold. Only at lower speeds too.

 

Alright here's an update:

After reading Waynerd's comment I took off the front driveshaft and played with the double cardan joint to find it's suuuper squeky. I'm in the process of rebuilding that now. Waiting on the second part order that takes like 3 weeks to get delivered. I'll update to let anyone wondering know if that's what fixed the issue

 

Did you try greasing it? Can't imagine it would be squeaky if it's greased. There's zerks for the ujounts and for the center piece, but you need a pointed adapter to grease it, don't recall the name of the thing but every parts store has them and they're cheap.

 

That "pointy adapter thing" was the best most practical investment I have ever spent money on in my lifetime so far. I have drilled holes in sealed bearing side plates and regreased them so many times now I can no longer keep count.

 

That is a needle. And I remember reading it took one to grease the ball and socket on the front shaft. But I don't think there's a way. Mine is still making obnoxious sounds when it's below 40 degrees. I have another shaft I'm going to try first. I can't afford to rebuild it at the moment. I still haven't rebuilt my rear shaft. Have the u joints but still need the double cardan joint. Running a non cv shaft in the rear for now and boy does it vibrate.