On 15 February 2006 at 06:06:14 UK time Dan Carty wrote:
>".... it looks pretty straight forward, but ...."

Simple in theory. Drain and remove radiator. Remove fan blade and side hose from water pump. R&R water pump with 4 bolts and a paper gasket. Reinstall other bits and refill coolant.

There are a couple of tricks to save the day. Try very diligently to not break the bolts if they are rusted in place. Broken bolts are a PITA to deal with. The problem is that some of the threaded holes go through into the water jacket. If the threads were not properly sealed last time around (very common problem) the water would leak through the threads. This causes rusting for the entire length of the bolt.

In really bad cases you may break the head off the bolt, and the water pump may be tightly jammed on the studs where the holes are filled with rust. If that happens, drive a sharp knife blade into the gasket joint to force removal of the pump body. Then use lots of penetrating oil on both sides of the block face, inside as well as outside. Use locking pliers to remove the broken bolt. Again, try very hard not to break the already broken bolts. If you end up breaking them flush with the block you have to drill and tap for removal. If you bugger up the original threads you may repair them with Helicoils, but it may be tough to keep the original location. If you get the Helicoils installed just a little out of position, you may end up having to file out the holes in the new water pump to get the bolts in.

When installing the new unit, no sealer is required for the paper gasket, because it is sandwiched between two machined metal surfaces. If you buggered up the surfaces with knives or screwdrivers during disassembly, then file off any burrs, and you might need a touch of sealant to fill any deep gouges.

The most important detail is to use thread sealant compound on the bolts during assembly to prevent coolant from seeping out through the threads. Thread sealant may look like gray grease, or it may be the white Teflon based stuff. A small tube of thread sealant is prety cheap and will last for many, many, many applications with just a touch at a time. Pick the stuff up at any local auto parts store.

Thread sealant is useful also for thermostat cover studs for the same reasons. Also useful to prevent oil weeping around the manifold studs to burn on the hot exhaust manifold. Four of these six studs go through to the vertical holes for the head bolts, so need to be sealed there as well.