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I discovered a small hole, possibly a puncture, in an outer CV gaiter on the front. The hole was right next to/under the (outer) metal ring holding the CV gaiter, so it wasn't in a very flexible bit. There was quite a lot of oily grease splattered on the inside of the wheel (and presumably much of it also went onto the road). The hole was then closed using silicone sealant.

What I would like to know is if the grease that was blown out of the CV gaiter still had a function, or whether grease that has reached the CV gaiter's "wall" is not useful anyway, because it doesn't go anywhere normally. Should the missing grease be replaced?

NB: Given the position of the hole, and the fact that the grease was pushing out, I'm fairly sure that nothing went into the CV gaiter.

The car is a 2001 Saab 9-3 (first generation; B205R)

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Excellent picture: you summarized the whole problem in one shot. –  Bob Cross Aug 6 '13 at 20:25

3 Answers 3

up vote 9 down vote accepted

Yes you need to replace the grease when you replace the boot. That grease lubricates the joint, if you don't have enough inside the boot the joint can fail prematurely. On a side note don't use one of the quick boots (the ones designed to be put on without taking the CV joint off of the car), in my experience they are worthless.

Here is an example of a boot kit, this one is $15.99 and fits a Dodge Neon

enter image description here

This is the split boot type that I don't recommend.

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As R.. Suggested the whole CV joint for your car might be only $60 and that's certainly something to consider, it's only about 15 minutes less work to replace the whole shaft than just the boot.

Here is an exploded view of the outer CV joint. It's best to disassmeble when cleaning the old grease and dirt out.

enter image description here

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+1 for great example pics, but I'm skeptical of the claim that the difference is only 15 minutes. If any dirt or debris has gotten in the CV joint, which is hard to avoid when taking off the axle and old boot, you're going to need to thoroughly clean it. And if you're not careful, parts are going to fall out, and making sure you get it put back together right is non-trivial if you're not experienced with CV joints. –  R.. Aug 8 '13 at 17:02
    
I'm looking at the relative size of the pictured bags, which, I assume, contain new grease. Am I to assume that, optimally and standardly, the boot is completely filled with grease, and therefore that, with some or much of it gone, the remainder will collect itself at either the boot's surface or the boot's bottom, but, perhaps crucially, not at the joint itself anymore? –  Glen The Udderboat Aug 8 '13 at 17:27
    
@R.. Once the axle is out it takes a couple of whacks with a hammer to remove the outer joint. From there removing the boot, race, cage and bearing only takes a few seconds more. Clean everything using a parts washer or degreaser to remove the old grease. Reassemble the bearing add grease and reinstall. If you never done it before I can see it taking a little longer, but it's really not that complicated again IMHO. –  Larry Aug 8 '13 at 18:03
    
@Gugg Most of the grease is inside the bearing and metal portion of the joint. You don't really put any of it in the boot. Some of it makes it's way into the boot once the wheel is turning. –  Larry Aug 8 '13 at 18:05
    
@Larry That seems to suggest that the grease lost wasn't serving (or going to serve) any further purpose and that the sealing of the hole, as long as it holds, will be a sufficient measure. Is that correct? –  Glen The Udderboat Aug 8 '13 at 18:15

Remove the shaft, and throw the boot away. Clean out the old dirty grease, after cleaning the part of course, and replace both the grease and boot. This gives you a chance to inspect the joint, and clean up any dirt residue that will speed up the deterioration of the CV joint.

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Honestly unless you enjoy making more work for yourself, I would just seal up the hole, possibly adding grease before doing so if it's not too difficult and you can do so without making the hole worse. Taking off and reattaching the axle is a big enough job by itself, without cleaning, re-greasing, re-fitting, and putting a new boot on the CV joint, that most people would just replace the whole axle when it needs done. (For most vehicles it's a $60-120 part.) But you might as well wait until it really needs it.

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I disagree, we don't know how much grease was lost, based on the picture it looks like a significant amount to me. Even if the grease was fine the boot flexes with each rotation of the wheel and any repair to the boot isn't going to last any significant amount of time. Boot kits cost $15-$20 in my area and take 1-3 hours to install depending on the car. While CV axles are $60 for a lot of cars, some are several hundred dollars depending on the car. IMHO I want answers on this site to be consistent with what a professional would do. If not we will never attract professionals to the site. –  Larry Aug 8 '13 at 15:30
    
OK, that's a reasonable viewpoint, but is it documented anywhere that only professional-equivalent answers are proper on this site? –  R.. Aug 8 '13 at 17:03
    
@Larry and R..: For completeness' sake, I'll mention that the car is a 2001 Saab 9-3 (first generation; B205R). –  Glen The Udderboat Aug 8 '13 at 17:42
    
@R.. That's why I said "IMHO", I remember Jeff talking about it in one of his blogs. Wanting the sites to attract professionals, like Stack Overflow. I think there are some issues with that for this site but it's too much to discuss here. –  Larry Aug 8 '13 at 17:52
    
@Larry I know this is a stretch, but is "any significant amount of time" specifiable? The puncture happened within the last 500 km and I plan to drive 500 km more before the new boot. –  Glen The Udderboat Aug 8 '13 at 18:38

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