Is my ball joint shot or is the rubber boot just torn?

The ball is still tight when I rotate it.

If the boot is torn it will let in dirt which will eventually lead to premature failure.

Yes, that's true so I'll get a new boot but the joint itself is still good. I think the PO had a mechanic pull the strut and he tore one. It's firm but rotates smoothly.

If you are going to go through the hassle of dropping the tie rod to replace just the boot (which I think is not available), I would just replace the tie rod. They are not expensive or difficult to replace.

Fill it with grease until you fix it.

Quotes source post: 15633540

+1..... and then replace the boot if you can get a new one. No need to replace a perfectly good joint if only the boot is torn. You don't only save money on the part but also don't have to take it in for alignment either.

Quotes source post: 15633562

That makes sense to me. Torn boot is not a trashed ball joint. Now that I've been in there I see it's not hard to remove and replace. How do you know when a ball joint is bad? The two main failure modes are wear related loosening and outright break. The second one is not likely, nor should it be a mystery. What about the first one, wear and loosening, how do you know?

It will let you know...

Should there be a photo attached? Where is this ball joint? As a generic answer, the socket will wear first. If dirt and debris are allowed to enter, this accelerates the issue. To test for slop - you can usually place a pry bar strategically to try and move the arm with respect to the knuckle (or whatever the two parts are). You may need to unload the car - or you may need to simulate load (i.e. as if the tires were on the ground). Movement should be smooth but should offer resistance. Not enough resistance will mean wear has begun. Loose or obvious (axial) motion will indicate replacement is needed. In the meantime, I would suggest injecting grease into the boot (there are needle injectors for this purpose) from a grease gun. Try to match the grease with what is in there. This is probably a bit of a crap shoot. A good black moly EP grease is probably a good guess. Once you've done that, wipe away any excess. Wipe it with a clean rag that is damp with brake clean or carb clean. Allow to dry for a couple of minutes and then apply a thin coat of silicone sealer over any cracks or openings in the boot. Then get a new boot. While you've got things apart to install the new boot - do a proper check of the ball-pin. You should be able to move in all directions, but not too easily. Re-grease everything and be sure to put a layer of grease in the boot.

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Thanks, yes, the ball is good and solid on the control arm. It could go a while if it's protected. My understanding is that these are nylon joints and don't need grease as much as other ball joints do but an intact boot it does need. No doubt there's no official boot but does anyone know the diameters or a good alternative? It doesn't need exact fit, I'll wire it on to keep gunk out.

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Might be cheapest and easiest to buy a cheap control arm and snag the boot off of it. https://www.rockauto.com/en/catalog/porsche,2002,911,3.6l+h6,1388314,suspension,control+arm,10401

The boot may not be replaceable. In many cases the boot is crimped into the metal during the manufacturing process to seal the grease in.

Just like with anything engineered, this joint has a wear limit too. Most ball joint have a few thousands of an inch of play before they go over the service limit and require replacing. Takes a lot of wear for a joint to pop apart. My Passat had an outer tie rod that was flopping 3mm up and down when I replaced it....................well passed the safe limit.

I have gone a year injecting grease into lower control arm ball joints. It stopped them from squeaking. Aside from the noise, if your joint is bad, you will absolutely hear and feel it especially when going slow of small bumps. I eventually replaced the lower arms. I didn't get an alignment until 2k miles later I realized my half worn tires were completely bald on the inner shoulders. I have since learned my lesson that the slightest change in any suspension part will probably result in needing an alignment. Now my tires have 8k miles and no signs of un-even wear.