I posted the following message on the E36 board because I drive an E36. Some of you in E34 5 series have the same engine, 2.5L6.
As you know, the E36 initially came with a plastic impeller on the waterpump, I think it was 92-96. model years. Later that was changed to a metal impeller. My 93 325ia with 69k on it still had the original pump on it. Yesterday on my way to work I noticed that all the sudden my temperature gauge was in the red, and the overheating light was on. Pulled over, inspected the situation, cooling fluid all over the place, but no apparant leaks. I let it cool off, idled it to a supermarket, bought some water, topped it off. I would not cool down. I squeezed the radiator hoses, no water movement. Called the dealer and a tow truck. Hour and a half and $56 later I'm at the dealer and ask them to do a pressure test. Two hours and $75 later the dealer shows me the estimate. Waterpump, radiator, thermostat, low coolant sensor, belts, gaskets bla bla bla, $ 986.43. Now I am getting pissed. My radiator is leaking he says. Well, I have been loosing coolant, about half a quart every 2,000 miles since the day I bough the car. When I bought it, it had 3 months/3000 miles warranty and I mentioned this coolant loss while it was still under warranty, but "they could not find anything". How convenient. So that explains that. Now this waterpump. A while back I took it in for inspection 1 and everything was cool. I find it odd that 9k later all of a sudden my waterpump bearings have "excessive" play on them. I'm scanning over this estimate to see how in the hell they came up with $968 for a simple waterpump and radiator job. The f$@#$%^& radiator alone costs $358. They didn't even have a waterpump in stock. Excuse me? No service car available either. Sir, we can call a rental car for you. I mention my disgust and disappointment that a car with only 69k on it, that never misses a service or oil change, has always been maintained at this dealer, needs an unexpected repair costing this much money. I tell them to get my car down, I pay the $75 and call a tow truck. I will repair this myself. They warn me that I need special tools to get the fan clutch off and a puller for the waterpump Two hours and $106 for another tow my car and I are home. Needless to say, I'm not going to work today. I call Bekkers and Bavauto, both will sell me the radiator for about $260, but can't get it Tuesday. On Saturday I call another dealer and after some wheeling and dealing I got a radiator for $300. pump, 2 belts, and a thermostat, tax, about $460. Still plenty. Less than 1.5 hr later I have the radiator off and the waterpump in my hand. No special tools required, just common sense guys. You can pull that waterpump off by putting 2 bolts in it, it has 2 threaded holes for that purpose. Piece of cake. The fan clutch takes a 32 mm wrench, but a crescent wrench works fine too. Oh by the way, that clutch nut has left thread folks. The hard part is to keep the fan from turning while you loosen that nut. I used a thin strip of metal (1/16" x 3/4" or so), drilled 2 holes in it and bolted the strip to the fan belt pulley with 2 of the 4 bolts in the pulley. Now you have something to hold on to and it comes off easily. It's hard to picture this on paper, but look at your fan belt pulley and this will make sense.
When I pulled that waterpump out, there was no impeller on the shaft. Pieces of the impeller were in the pump housing. I puzzled it back together but I was still missing quite a few pieces. Took a garden hose and connected it to the hose that goes on the expansion tank and flushed it. Out came all the missing pieces. About 2 hrs later I got it running again, and I was in no hurry. So all in all I was out 56+75+106+460+18 (cooling fluid) = $715. A bad day, but I saved about $300 doing this myself. It was much easier than I thought. Still, I don't know exactly how long I had been driving with my temp gauge in the red. It doesn't take much to blow a head gasket and crack a head. Not to mention the inconvenience of getting stranded, miss a day of work, pay for tow trucks etc. A stupid $80 pump is not worth it guys. Your bearings will get play in them, the impeller will get stuck against the inside wall of the housing and shears off the shaft in mere seconds and that;s the end of it. All you got left is a spinning shaft. If you still have a waterpump in your car with plastic impeller, replace that thing as soon as you can, before this happens to you. And don't be afraid of attempting this repair yourself, it's really quite do-able. If all you need to do is the waterpump, you can do it in an a little over 1 hour.
P.S. Leave the fan blade on the clutch.