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CV joints and U joints

On inspection of my car, I was told that my CV joint seal was leaking and also that my U joint was busted.

My questions would my car still move if the U joint was busted and should I have the whole CV joint replaced or just the seal? They want like 250 just to replace the seal and to regrease it. Also is it dangerous to drive with these issues??


It would help if you posted the make, model, and model year of your vehicle, as well as whether it is FWD, RWD, AWD, or 4WD.

Let’s try and guess, whar car/truck has both CV and u-joints?,maybe a 4wd pickup with a independant front suspension?,I really don’t know,something like a ixBMW?,and when the op says CV joint seal you think they mean the boot?

its a '99 Chevy Suburban and yes its 4WD. I don’t know much about cars and was just told that the front left CV joint seal was leaking and needed to be replaced and regreased.

When a CV boot is cracked, it is common for the CV joint to become contaminated with dirt and grit and this contamination will seriously limit the lifespan of the joint. As a result, most mechanics would advise replacing the joint, rather than just replacing the boot. Can your mechanic give you some assurance that the CV joint has not been damaged by water, dirt, road salt? If not, you should replace the CV joint, which comes with a new boot.

Regarding the U-joint–are you referring to the U-joint on the driveshaft that transmits power to the rear wheels? Or, are you using the terms “CV joint” and “U-joint” interchangeably, and actually referring to the CV joints on the front, rather than the U-joint on the driveshaft?

Thanks. I am gonna have that CV joint looked at tomorrow.

Nope, I am referring to the actual U joints on the driveshaft. I was told that the front u joint was all busted up. Sorry about the confusion.

A busted up U joint make a heck of a racket and vibration, did yours?

“Also is it dangerous to drive with these issues??”

If the front U-joint on your driveshaft breaks and the front of the driveshaft hits the pavement, your truck will attempt to do an imitation of a pole vaulter. Yes, that could be dangerous when it digs into the pavement and stops you VERY suddenly.

It doesn’t vibrate, but I do notice a knocking type noise coming from under the suburban when driving forwards and backwards.

I am having the CV joint and the U joints looked at tomorrow by a mechanic near my house. My husband had the U joints changed out about a year and a half ago. UGH!

U-joints fail very rarely, something odd here. They need to check for possible causes, like a bent driveshaft, missing balance weights, etc.

Yeah! I am thinking that the driveshaft in unbalanced, possibly as a result of losing some balance weights.

1 1/2 years is far too soon for a U-joint to give indications of failure unless there is some underlying problem.

Could driving it in low 4WD have busted them? A few weeks ago when I got the catalytic converters changed out the guy had put it in low 4WD and I thought he got it out and stepped on the gas and it made a noise like it does now but louder!!!

No, using 4wd low should cause no problem. It does make me wonder if there’s some problem in the 4wd system, though. Sorry!

I was told that there is a leak in the transfer case. Not sure if that will affect anything.

Nothing to be sorry about. I have had one thing after another with that thing that nothing surprises me anymore!