Before removing the water pump, a few words about what pumps to use and what precautions and other services should be considered at the same time.
While they are off, consider the condition of the drive belts. If they show cracks or glazing on their edges, or if they are more than three years old, they should be replaced. Have a good look at the condition of the alternator bushings. Their condition greatly influences the life of the belts and the bearings in the water pump and the alternator. See the page on bushing and belt replacement if you need more info. While doing the water pump replacement, tighten any cooling hose clamp you run across. Some, particularly the ones at the rear of the water pump, never get tightened and will leak if not tightened periodically. Now is a good chance to get those hard to reach ones.
Drain and flush the cooling system while it is down and before beginning work. This will insure a long life from the new pump and the rest of the system. If the thermostat is nearing its life's expectancy of 30000 miles or two years, replace it at this time. Refer to the cooling system service page for more details.
Loosen the AC belt tensioner by loosening the two bolts on early cars and the three on later ones. The third bolt on the later ones also holds the power steering belt too. Then run the 13 mm nut on the tensioner arm all the way to the end of the tensioner. You can now remove the AC belt. I go ahead and get the tensioner out of the way by removing the bolts holding it on. The short pulley tensioner on the early 8 V's has no adjustment arm. Use a wrench on its bolt through the pulley to re tension it, tightening the securing bolts while holding tension at the big bolt.
Remove the alternator belts from the water pump pulley. I suggest reaching in now and breaking the water pump pulley bolts loose. Don't remove them, just break them loose while the belts are preventing the pulley from turning and giving you a little help. On early 8 Vs. there is a 13 mm nut on the back of the upper tensioner arm at the alternator. On all others it is a 17 mm. Remove the nut, pull the alternator towards the left fender slightly, actually tightening the belts slightly and slide the tensioner out of the top of the alternator. Then push the alternator to the engine. This is easier accomplished from the right side of the engine by inserting a long pry bar between the chassis and prying the alternator back to you while reaching in and removing the belts. Let the alternator lie on the left fender well, or as far as it will go toward the left.
Now unplug the ac compressor's connector. And then the compressor, bracket and all. It is my experience that the better you can reach and see the object you are working on, the better your repair turns out. Getting the compressor out of the way takes a few extra steps, but the benefit in making sure the sealing surfaces are clean makes the effort well worth it. Leave the lines attached and the refrigerant charge intact.
On early 8 Vs., remove the two upper bolts holding the bracket to the engine. The rear one under the line that goes into the intake manifold requires a wrench. I loosen the other two bolts first so I can lift the compressor as that rear bolt comes out. Just leave it in its hole under the line when it clears. The bottom bolt on the ac bracket can be a struggle the first time. A long 3/8 extension (24") and a swivel 12 mm socket greatly simplifies its removal. Get it loose, then by picking up slightly on the compressor, it can be turned out. On later 8 Vs., remove the two nuts and bolts at the top of the bracket and loosen the lower one. The bracket should be slotted at the bottom and will slide out from under the lower one without removing the bolt all together. More on this in the 16V section.
On 16V engines, remove the two 6 mm Allen's holding the bracket on at the head. Then loosen the lower 12 mm behind the alternator. On early cars the ac bracket is not slotted as on early 8 Vs. and the bolt must be removed to get the compressor out. It tends to hit the alternator. Careful (sometimes forceful) maneuvering can get it out. Once out, if you bent the bolt getting it out, find another to take its place and go ahead and start it back in the hole. Then modify the ac bracket at the bottom as the later model ones are, namely cut a slot to allow the bracket to slip back over the bottom bolt, cutting away the lower part of the bracket, notching it to fit over the bolt and resting in its original position. Sawing straight up to the edges of the bolt hole with a hacksaw will do the trick nicely, a slight flare at the very bottom makes alignment easier. The bolt has a lip on its edges to grip the bracket and all will be fine. Some of these lower bolts can be quite a chore. If all else fails, you can loosen the lower bolt holding the alternator and slide it as far forward as it will go. This will let the alternator drop enough to remove the bolt. Later cars are slotted and all that is necessary is to loosen the lower bolt and pull the compressor and its bracket up.
When you free the compressor, swing it to the right with its lines. Rest it to the right out of the way. but be careful not to strain the lines too much. If the engine harness has been tie wrapped to the hoses, cut the wraps. Remember to replace the tie wraps when finished so that the harness can't fall back down into the spinning belts. The resultant mess can be expensive! If the original harness tie wraps tied to the front of the head by lugs feel hard and brittle, it is is a good idea to go ahead and replace them now with new pliable ones to prevent the old ones from breaking and dropping that harness on the belts.
Now to the water pump. Remove its pulley by removing the four 10 mm bolts holding it to the pump. Be careful to retain the washers with them. The washers are thick and actually adjust the length of the bolt so it won't interfere with anything on the other side. Then remove the 5 12 mm bolts holding the water pump to the timing cover. Some water may be left in the block and it may come out when you remove the pump, so have a pan in the appropriate place.
Note the position of the two long bolts. You need to clean the bolts if they show corrosion or rust. Replace any in bad condition, Only on the two longest bolt should you place a thread sealant just to be sure. Clean the surface of the timing cover of the old gasket. Whatever you use, be careful of the surface. It is aluminum and can easily be unevenly sanded. Careful use of a razor blade and elbow grease with a pot scrubber are much preferred over inexperienced use of power tools. Get that surface damaged, and you will be replacing the timing cover before you stop the water leak.
For a sealant, we highly recommend Loctite's Anaerobic Sealer #518. Place it on both the sides of the gasket, on the water pump and on the timing cover sealing surfaces. Make sure the surfaces are clean and dry. This sealer will seal unbelievably and leave no sloughs like silicone to break loose and travel to the worst place it can possibly find to live for a while. A large tube of it will do many many repairs. It is the factory recommended sealer, in some places, taking the duties of sealing without a gasket. Install it with the clean bolts and torque them to 200 in/lbs. Note INCH Pounds. Not Foot Pounds. This is a good hand tight torque. Reinstall as you removed the parts. Don't forget to close the radiator drain if you left it open and bleed the cooling system. See Cooling System Service for details.
As for what brand of pumps, we highly recommend sticking with the factory pumps. After-market pumps are available less expensively, but they are indeed cheaper. A simple comparison will show that most of the after-markets use a stamped impeller that can easy separate or dissolve from the shaft. The factory impeller is cast. The shaft is smaller on the after-market pumps. The bearings are not as high quality either. We have yet to see a factory pump go out with no warning. You will notice a drop in coolant or hear a noise first. We have seen many after-market ones lock up tight with no warning what so ever, throwing the belts at the least, ruining crank sensors or timing covers and engines at the worst. The difference in price is not that great to warranty the risk. If you have a after-market pump on the car, pay extra attention to it, and when it fails, replace it with a factory unit. if you suddenly get unexplained overheating, remove the after-market pump and see if the impeller has dissolved away to nothing. This is not uncommon, especially in neglected cooling systems.
When tensioning the belts,
avoid getting them too tight. If you can't fairly easily deflect the
belt at least an inch at its widest span, it is too tight. This
eliminates as much strain as possible on the belts and the bearings
as well as the front pulley. Make sure the bushings for the
alternator do not allow it to vibrate or cock, misaligning the
belts.