What engine?

Usually, the water pump seals with an 0-ring on the newer engines, but I'm not sure on the aluminum V8s, could still be a gastet.

If so, use rubbing alcohol, the sealant is usually something like Permatex. Do not scrape with a steel implement, you WILL gouge it badly! I use Aircraft (red painton) Permatex on everything like waterpumps, it's eaiser and seals better. Make sure you completely coat the gasket, sometimes they "melt" if coolant gets to the gasket material and you DON'T want to do this job again just for fun!

Use NeverSieze or something similar on the bolts going into the block so they won't stick, bolt sealant isn't necessary. Coat the shaft of the bolt a bit, too, so it won't stick in the water pump, either.

If there is an o-ring seal, put it in dry after getting the block completely clean. If you use sealant, you normally cause leaks because the sealant will set up before the o-ring "seats" completely. Same reason you don't use sealants on the old "lace" window gaskets.

You may need to use some vinegar to get calcium deposits off the block. Use scotchbrite sparingly, too -- you can grind enough material off to cause leaks if you get carried away!

Expect to replace a bolt or two on the thermostat housing of it was leaking at all, the bolts are small and sieze pretty easily.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!