What temp do u-joints usually run after highway driving?

MutantNinjaTJ

MutantNinjaTJ

TJ Addict
Supporting Member
Joined
Jul 21, 2018
Messages
1,381
Location
The sewers of Newer Mexico!
What temp do u-joints usually run after some highway mileage? I'm trying to see if I have a u-joint issue by checking the temp on the end caps with a temp gun. The fronts were 130* and two of the rears were right there but the other two that are strapped in place were 141* This is the rear u-joint on the rear shaft. I have a squeaking sound once it warms up a bit and so I redid the front shaft including the centering ball thinking that was the problem. I had changed the rear shaft u-joints a year ago when I bought the Jeep so I thought they were good. Took it to my Jeep guy who did the gears and they couldn't determine the squeak so I thought about using the temp gun to isolate the problem possibly. I am going to install two new u-joints in the rear axel tonight to see if that was it, but I'm curious if my troubleshooting method is a valid way to see if one is going south on me. I have two hard days of wheeling planned for this weekend and the squeak is really bugging me. What do you think?
 
The only definitive way that I know of to find out if a u-joint is bad is to pull it out.

Pull it out and you'll probably have a good idea if it was squeaking or not. If one of the caps is full of powdered needle bearings you'll have a real good idea.
 
Before replacing them, drop the driveshaft and move the u-joints around to see if they feel good or not, and as suggested above look to see if there's any rusty-colored dust coming out from under the bearing caps. A good u-joint will feel smooth/well-greased in all ways it can be moved.
 
I hear you, but since the rears were fairly new I didn't want to pull them down to inspect. Based on my temp readings I think the rear u-joint is my Huckleberry! It's only going to cost $20 and some cold beer to find out. I pretty sure they aren't "powdered" just yet. I fist thought it was the centering ball on the front shaft, but while tearing it down I didn't find anything that led me to believe I had found the problem, and sure enough I hadn't.
 
Those temps don't sound high enough to worry about. See how long you can hold your hand on your rear differential cover after you have been driving it even though everything inside is fine.
 
Top Bottom
Back