I changed a Water Pump first by draining the Coolant and there are some bolts that need to be loosened to take the Water Pump off.
Make sure you a Gasket on the New Water Pump and use sealant to prevent Coolant leakage.How do you change the water pump on 1978 Cadillac Hearse?take the old one off. then put the new one on. its not that hardHow do you change the water pump on 1978 Cadillac Hearse?Drive it or tow it to your nearest mechanic, fork over some cash, write a check, or give them your credit card to charge.How do you change the water pump on 1978 Cadillac Hearse?Its not too bad on those. Thats the 7.0 425 Cadillac motor. Parts stores should have the pump or easily be able to get it. The same pump fit most Cadillacs from 68-81. The Hearse is listed in the books as a Commercial Chassis, if they dont have a listing for that then just get one for a Deville with the GAS 7.0 motor.
First disconnect the battery. Next you need to remove the upper radiator shroud. This gives you a bit more room. There are then 4 bolts that hold the fan on to the pulley, remove those so you can remove the fan. Drain the system, there is a drain valve at the bottom left side of the radiator. You then need to loosen the belts. The front belt loosens with the alternator, it has 3 bolts. One easy to see on the top. One on the back and one underneath. Loosen all 3 and the alternator will slide so you can get the belt off. Back belt is the same setup except this time on the power steering. Same 3 bolts except its bottom, side, and back. With the belts out of the way the pulley will just come off the front of the pump. You can then unhook the lower radiator hose. Now you just need to remove the 11 bolts that hold the pump on. and remove the pump. Clean up the mounting surface. Put a thin layer of rtv on the new gasket let it sit for a 1/2 hour to an hour then put it back together finger tight. There are 3 sizes of bolts. The smallest ones get a bit of RTV sealer on them. Torque on the 4 big 3/8 (9/16 head) bolts is 22 foot pounds. Torque on the 3 medium 5/16 (1/2 head) is 15 foot pounds. Those are not real sensitive because they go into the cast iron block. The last 4 small 1/4 (7/16 head) bolts only go into the thin sheet metal timing cover and are very easy to strip out. Torque on them is 70 INCH pounds. Thats only 5.8 foot pounds. Thats holding a 1/4 drive socket wrench with 2 fingers. The rest goes on the way it came off. While you are there its a good time to replace the lower hose and the belts if they need it.
