3800 Water Pump Replacement


One of the Reattae must have gotten wind that I was thinking about thinning the herd because it took a wee on the floor. Traceing back it could be seen (with a mirror) that the water was coming from the weep hole in the water pump meaning the pump seal had gone.

New pumps from the "Boys of Vigor" being $36 (2011 price for Bosch 97134) there is no reason to use a rebuilt.

Good news is that there is only one job on a Reatta that is simpler than a water pump, and that is replacing the alternator.

Begin with draining the cooling system down to beneath the bottom of the water pump. If not drained it will come out when the pump is removed.

Now loosen the four screws (10 mm socket) that hold the pulley wheel on the water pump hub. This is easiest done with the serpentine belt helping hold the pulley from turning.

Next remove the serpentine belt (and is a good time to check that for wear). This requires an 18mm socket and a two foot (or more) breaker bar to remove the belt from the idler pulley. Lay the belt down (89-91) or remove (88)

Remove the four screws in the hub (a magnetic parts pan is nice) and the pulley wheel. This exposes the pump body and screws. Nothing else should need to be removed.

Next there are four screws that require a 10 mm socket (4" extension is needed for socket wrench to clear other sharp items), three on top and one at bottom center. These are followed by four larger scews that take a 13 mm socket, two at either end.These may be gummed up and come out tight.

At this point you should have 12 screws with washers: 4 short (hub), four longer (water pump center), and four larger (water pump ends). I clean these with a wire brush and apply never-seize lubricant to the ends.

When all eight bolts have been removed, all that is holding the old pump on is the gasket. Unfortunately some sealers are a lot like glue. In this case a few sharp raps on the hub with a soft mallet should pop it loose. Do not try to pry between the timing cover and the pump because the cover is soft aluminum and scores easily. Remember the guide pins allow it to be removed straight out only.

For me the next sequence takes about an hour: getting the block surface really clean using an assortment of scrapers and emory cloth.
1) Use chisel scrapers to remove the gasket material paying particular attention to the area around the two guide pins.
2) Use razor blade scrapers to remove all remaining traces of gasket or sealant from the timing cover.
3) Repeat and continue until there is nowhere on the mating surface that you can catch a fingernail. The photograph shows a surface that is Not Good Enough. I take photographs to see what is not obvious.

4) Once scraped completely smooth, use emory cloth to create a uniform surface.
5) Wash surface with solvent to remove all particles

The last prep stage is optional depending on how the bolts felt coming out - running a tap through the 8 threaded holes. Clean taps after every hole.

Reassembly is now possible. Since a gasket should have been included with the pump, that is what I use (do not care for "make your own" silicone) but first I apply a thin layer of axle grease to the whole gasket. This has two purposes: a decade hence when a new pump may be needed, the old one will come off easily and cleanly. Also the grease will help the gasket to stick on the block while attaching the water pump.

Put gasket in place using the guide pins as, well, guides. Have screws handy and place new water pump in place over gasket and guide pins. I begin with two of the larger screws, one in each end, just finger tight to hold the pump in place. Next screw in the other six finger tight.

I now snug down the smaller screws and then the larger ones. Then tighten alternatively with a 1/4" driver. Final torque spec is 8 lb-ft for four smaller screws and 22 lb-ft for four large ones. Hub is 10 lb-ft. Do not play godzilla (and if surface is properly prepaired, you will not need to.)

Once the pump is in place, install the hub pulley and snug screws, then install the serpentine belt and tighten the hub pulley screws.

Refill the radiator and run at idle, revving a couple of times to 2500ish rpm to burp the system. Refill again, it should need about a gallon to five quarts.

Once full, replace the cap (to build pressure), let the engine run up to operating temperature, and check for leaks (fixing one thing may expose others).

If none then all that remains is cleanup and putting tools away.