Lets talk water pumps...

After talking to another forum member, he brought up a good point I had already been thinking about... Been working on cars of all types for many many decades. Whenever I smell that maybe even faint, but unmistakable sweet scent of antifreeze coolant I know there is a problem developing. Even if no puddle under car, not even a drop on the garage floor, that sweet scent means something. Seems to me the very first sign of a water pump getting worn is that sweet smell, with maybe a tell-tail sign of a stain or droplets on the water pump weep hole area. Water pumps have a mechanical seal that is very intolerant of excess play in the bearing. As soon as the bearing has the slightest amount of excess play most mechanical ceramic water pump seals start to seep. They seep way before you can even feel any meaningful play in the bearing. Now if you let this go on for a while the bearing will wear more and more and start to make noise and the seal will seep more and more at the weep hole till its got a leak on the floor. By then it might be to late for a 996. IMO, that sweet antifreeze smell will happen way before enough play in the bearing happens to let the impeller contact the block. I would have to guess the pump bearing would be making noise way before its lose enough to damage the block. Anyone know the exact clearance between the impeller and block..? So, for a aware 996 owner that listens to his car engine, wouldn't it be better to have a pump that doesn't have plastic impeller vanes. Plastic vanes that commonly break off and clog up coolant passages causing cracked heads..? Seems the chance of your block being damaged by a worn out bearing/metal impeller would take a totally numb owner that doesn't pay attention to that sweet smell of coolant and or new engine noise... no..? jmho

My original pump lasted ~60K miles. It was weeping and making subtle noises. No damage to impellers or block. Not being aware of the block damage potential, I replaced it with a unbranded one with metal a metal impeller. It lasted ~70K miles, and failed with threshing machine level noise preceded by weeks of traces smell of coolant. I feared block damage, but surprised to find it pristine. After some research I opted for the GEBA for my recent replacement. A good bit of that decision was based on a response GEBA gave to a member on another forum, as quoted by that member: "We started production of the new pump 15007 at the end of 2012 and decided to utilize a metal Impeller because of the known Problems with the plastic ones. We also decided to utilize for these pumps the original bearing which Porsche is using for their production series which features an added Roller Bearing design which will reduce radial and axial play to a minimum. Also the distance between the pulley and Pump housing are extremely small, so if bearing failure would occur the Impeller could not move significantly into any direction"

I believe the plastic impeller breaks apart when the bearing has enough play to allow the impeller to hit the block. I have seen a change in the plastic material used on the impellers over the years (changing from black to a brown colour) so it's possible the new compound does not break apart as easily if it contacts the block. It would be interesting to hear from anyone that has experienced the newer material breaking apart.

I look at it as just an oem replacement part every 5 -7 years. Not an expensive part either. Sure, if there is a great aftermarket option that's better, I am all ears. But it's such a simple maintenence item, why not keep it fresh and steer clear of the issue.

I have disassembled the OEM water pumps before. The center section reminds me of a "Mini IMS " with a sealed ball bearing on one end and a plain bearing/bushing on the other. When the "lifetime" grease gets washed out of the ball bearing and the ***** fall out is when the real damage happens...