Leaking CV Boots

My right-sided, outboard CV boot has started to leak a small amount of grease; I recently had the left-sided boots replaced by the dealer (at some expense, because the outer boot was leaking on that one as well). The arrow on the picture below indicates that the grease just appears to be leaking at the end of the boot before the bearing housing. There doesn't appear to be any tear in the boot itself, and there doesn't appear to be any easy way to tighten the retaining bands on the boot, or make the seal against the housing any tighter. When I took my car into the dealer for the left-sided leak, they told me that the high lateral g-forces on the track were probably causing the problem by forcing small amounts of grease out through the end seam. They felt the only way to fix it was by replacing with a new boot which would fit tighter on the axle. With all the 987s on the track, I'm surprised that I can't recall seeing this problem reported before. Has anyone else faced this issue, and if so how did you deal with it? Any other recommendations?

You probably know more about this than I do. However, I would be very skeptical that lateral g of less than 1 would cause the leak you describe. I would be more inclined to believe that the dealer wanted some work to do, wanted to stop the leak, wanted to replace the left boot, and didn't really know the cause.

I too tend to think the G force business is BS... Are you sure you can't tighten the clamp? It should be one of two types... crimp, in which case you might be able to "extra crimp", or screw down, which obviously you could alter

Mine leak and I know my mechanic tried to tighten them but couldn't, I just live with it. The grease is a PIA to clean too. Edit: I'm not sure where they leak, I just know grease drips on the inside of the wheel during DEs, it used to drip a little all the time.

Why not cut the bands off and replace them with ones you can tighten?

As suggested those band clamps can be replaced, but I'm not sure you'll see an improvement. If you cut the existing clamp and try to clean the sealing surfaces I think you find it nearly impossible, but you might be able to get a new clamp just a bit tighter or at least enough to make a better seal. And then again you could get the clamping tool and try to get a tighter fit. This tool looks decent: Amazon.com: Lisle 30800 CV Boot Clamp Pliers: Automotive

There has been a discussion on the Cayman Register on this topic as well, and a couple of people there have reported some success at removing the existing clamps, cleaning the axle surfaces and repacking the boot with new grease, and placing new clamps (which do require a special CV boot clamp tool). The alternative is removing and replacing the boots with new ones (it is usually recommended to replace both the inner and outer boot if you are removing the axle anyway) - a much more laborious (read: $$$) procedure. It appears that this may not be a rare problem among those of us who track our cars; the common wisdom thus far is that the sustained high temps around the outer boots (e.g. from hot brake rotors, exhaust pipe, etc) tends to liquify the lithium grease more, and this perhaps combined with the high lateral g's tends to force some of the grease out through the end of the boot. In any case, placing new clamps is probably just a temporary fix for those who regularly track their cars.

Resurrecting an old thread here. I was wondering if others have experience with DEs and leaking drive shaft seals. Just completed two wonderful days at Road America, and following the last session of the last day was parked in the paddock with engine idling to keep the water pump and fans running when after about three minutes suddenly a gush of lubricant like thick oil came pouring out of the left rear wheel hub area. I'm no expert, but my guess is it's due to leak in the drive shaft seal. I was able to drive home (about 150 highway miles) with no further detrimental effect - no strange smells, grinding noises, etc. So I'm trusting that I can drive the car to the repair shop without too much issue - not as if all the oil had drained from the differential, for example, right? (I know from experience that if you drive a couple miles with no differential oil the diff becomes toast.)

FOLLOW-UP : I recently repacked and replaced the clamps on one of my CV boots which was leaking quite a bit. I documented the procedure in an Article here: Repacking and clamping CV Boots - Articles

Great write up! I'll be trying to do the same. One of my boots is leaking, and I've never driven on the track. I think all the commuting driving during summer temps will liquify the grease just the same.

Is there a part number for the larger adjustable clamp?

The official OEM part # is 996-332-957-00 which is supposed to fit 70-74mm, however I found it to be too large. The one I bought from my local dealer isn't an official Porsche OEM part, so I'm not sure who makes it. Others have posted using the following successfully Oetiker CV68 CV Clamp .

Worm gear type hose clamp works very well.

There are also the belt-type of bands that are one size fits all and use a tool you put a ratchet on to tighten. I'm a big fan of that type.

I used these EMPI CV Boot Clamps Amazon.com: EMPI CV Boot Clamp: Automotive View attachment 34551 with this OTC 4623 CV Joint Banding Tool And Cutter OTC 4623 CV Joint Banding Tool And Cutter : Amazon.com : Automotive View attachment 34552 I was generally satisfied with it but I never felt like it was tight enough. I broke one of the clamps when tightening but it may have been good enough. Louis

This is likely what is really happening. The grease will break down with time and as its viscosity drops it will pass through seals easier than before resulting in leaks. The right correction would be to pull the boots back, clean and replace the grease. The question now is, how frequently do you do this?

Tackling this job tomorrow - if will call parts pickup goes according to plan. Thanks for the great info, I thought I'd share my parts shopping experience: Amazon Redline CV2 cartridge $12 (since it's free shipping when bundled with my Xmas shopping) Harbor Freight Grease Gun $16 O'Reilly Performance Tool W83013 $10 Pelican Parts Clamps 911-332-257-00-M395 CV Boot Clamp, 73mm (sold per each), 996-332-957-00-M395 70.8 - 74 mm ​ 928-332-257-01-M395 Axle Boot Clamp (34 mm) 996-332-257-00-M395 39.3 - 42.5 mm​ I believe the car takes a 67mm and 43mm, but I ordered other sized clamps from Pelican to be safe. At $1 for one, it's cheap insurance to order everything. Pelican does not have a 67mm clamp. So if the 70mm+ clamps are too large - I also ordered a smooth band clamp (designed not to cut into hose materials) from McMaster-Carr until I locate a proper crimp clamp. Fallback is to mail order the Oetiker CV68. McMaster 2"-2 3/4" (50-70mm) 3/8" band PN: 5574K19 $12 for pack of 10

Here are my highlights of doing the outer boot: I used a dremel tool to cut off the clamps. Even the tricky one. This was easy and went fast. Be careful not to damage the boot. Also I covered the boot when operating the dremel. For the tricky one, I simply grinded off the retaining studs and use a 90deg plier to pull it off. Once the leak develops, it will leak constantly. In 4,000 miles (2.5 months) my wheel got coated in grease. The large clamp on the boot was loose. I could spin it easily by hand. This should be an easy test to perform. And you can do this easily without jacking the car up. This should be checked at every oil change. Catch it early, and you can probably just replace a clamp. The grease gun works!! Absolutely use this. It looked like it would be time consuming and messy to mash in grease by hand otherwise. The large clamp is smaller than the 70mm (stamped 67) I had to resort to using a smooth band clamp to make sure it was tight - until I source a proper clamp. The worm gear bulges the clamp channel lip. And I oriented it to contact the outer joint. Thus avoiding mashing the boot itself. The small clamp is a close fit. Not happy with it. Might look for something snugger than 43mm. Put shifter in neutral and take off the parking brake once jacked up. You can spin the axle easily by the rotor or the axle shaft itself. It took me about 2 hours to do the job while taking pictures. Not very difficult except for trying to put the boot back on the joint. More pics in next post

A few more pictures

Today I decided to check on the RH side inner CV boot which had a small leak. It turned into a major leak. *sigh* Grease was splashed all over. The large clamp is indeed the funny 67 stamped Oetiker clamp again (like the outer) To get access, you'll have to remove the tray. I didn't feel like tackling this, since I might as well replace the transmission oil at the same time. So there was enough room to slip on a smooth band worm gear clamp over the Oetiker. Worked like a charm! Snugged up the loose clamp until I get the 68mm clamps and gear oil. These 67 clamps suck. Boot was spinning on the joint same as the outer joint. Recommend keeping tabs on your 67 clamps.

My CS has started the CV boot leak also. It has 62k with some track use. I talked to a tech at my local dealer who said he is seeing this quite a bit on Cayman /Boxter's now that they are racking up miles. He stated that the boot itself stretches and that a clamp change is not a long term fix as the grease will escape the old, stretched boot. For those of you that have replaced grease/clamps only: How has the fix worked out? I am planning to put grease/new clamps on but wonder just how much time I am buying?

I replaced one large clamp over a year ago and its still fine. Another started leaking last month so I just replaced the other three. Buy the correct size from Belmetric !!! The ones I took off the car are marked 67 not 70 or 73. The bigger ones will not seal properly. Ask me how I know.

I disagree with your tech. The 67 style clamps don't provide enough pressure. You should go back and reread my recent posts and see pictures. As long as you avoid losing too much grease... Stop driving it. All you need to do is replace a clamp. See my advice above about catching the loose clamp early.

Thanks for the quick responses. Belmetric clamps are on order! I will replace the outers and wait to do the inners when I change my trans fluid again. Fingers will be crossed hoping for no more leaks.

So during my clutch replacement, I spotted my third loose clamp out of the four. Not leaking grease, but I could move the boot with little hand effort. I verified you can remove either style of clamps with a flat head / chisel and a few strikes on the tool with a hammer. So no need to get dangerous with a cutting wheel. For the leaky clamps, you just want to bend the retaining nubs away to release the clamp. For the replacement adjustable Oetiker crimp style, you want to bend the adjustment nub up - it locks the clamp into a fixed circumference. Then use pliers on the clamp end and pry it up and off that nub. So any guesses when my final (the fourth) clamp will loosen up?

Inevitably in the middle of a track day. Or when you're sitting on the 405 northbound at 5:30pm on a Friday.

I've recently begun acquiring "old car" experience - a 1987 928. I just replaced all the CV boots. The outers were torn, one perhaps for a few years, the other perhaps for a decade. Not many miles, though, and not much in bad weather or at all in the winter. No track time, no hot brakes. Some observations that may or may not be relevant to this thread: It's an unpleasant job since a lot of grease was still in the joints (!), which must be cleaned out. For the inner, non-torn joints, it was quite amazing how little the grease had moved - there was no grease on the boots much beyond where it was applied to the joint. On the other hand, the escaping grease from the torn boots truly makes a mess. The joints were OK despite whatever crap had been entering them through the torn boots. This is not unusual, from what I've read - they are surprisingly resilient. Put grease only in the joint, fill the whole boot, or something in between? I'm sure there are strong opinions, but no consensus. Filling them makes them leak, some say. I got the sense the grease doesn't migrate far, and the CV joints are not delicate, so I only filled the joint area (balls and "races"). Track use is a different situation, I'm not considering that.

2006 CS larger CV clamp calls for part number 99633295700 which is a 74 mm clamp. Yet it's too big. Turns out that he removed clamp is a 70 mm. Now it's Saturday and my car is in the air until I get the correct size.

Would this be the correct set of clamps? Part: 16300029 Crimping range in mm, 59.5 to 68.0 https://www.belmetric.com/oetiker-ear-clamps-large-sizes-c-15_841/cv68-cv-boot-clamp-p-1006.html Still trying to find the other clamps.

Yeah that's the right one CV68 - order CV40 for the smaller end too in case you need it. The minimum order + shipping costs are annoying. Order plenty in case you mess up crimping them.

Perfect. Thanks Jeff.