The grease shouldn't just pour out the bottom. If that's the case then it's like rusty says the cap may be missing. When you pump them full of grease it usually oozes out from the middle part where the two parts swivel or where the roll pin is then after that it will start to come out of the bottom where the cap is but by that time it would be minimal as the centre part is where the pressure relive is for the new grease going in and should be letting a lot of the old grease out.
I bought and fitted recon kingpins to mine about 1000 miles ago and I use an air powered grease gun and even with all that pressure behind it it doesn't pour out the bottom much. Old grease just gums up over time and as the pins and bushes deteriorate you end up with a metallic gum kind of substance which just aids the wearing process hence why it's really REALLY important to keep you pins greased
- the manual says every 1000 miles but I'ld go for every 500 myself. You don't need to remove the wheel and it only takes a quick blast from a hand held one (two or three pumps) just to push the old stuff out.
