This procedure will guide you in replacing the lower radiator hose on a 99 Cadillac Deville. The process may be similar on other model year Devilles, but only you can determine that. Read through this procedure first before you start the repair. Please feel free to post any questions or concerns about these instructions.


Tools and Supplies Required

Tools:
7mm, 10mm and 13mm 3/8” drive sockets
3/8” extension (at least 3”)
3/8” drive ratchet
Large slot screwdriver
Channel Lock Pliers

Supplies:
Two 2” hose clamps (if you so desire)
New lower radiator hose purchased at your local autoparts store
Hydraulic jack to raise vehicle (if necessary) and floor jacks for support of vehicle

Procedure
Disconnect battery.

Remove the cap from the expansion tank.

Remove the three plastic poppers that hold the black plastic cover over the radiator header and headlights. There are velcro fasteners at each corner.

Disconnect the sensor from the air filter housing and remove in order – the connector from the housing to the throttle body, the top part of the housing, the air filter and the bottom part of the housing (push in the center of the rubber grommets to release the bottom housing).

Remove the three 13mm bolts (two on top and one in front) holding the driver’s side engine brace and swing the brace toward the back of the engine so it is out of your way.

Remove the two 7mm screws underneath the frame holding the driver’s side cooling fan in place. Your 3/8” extension might be handy here.

Remove the two 10mm bolts holding the driver’s side cooling fan to the header and then slide the fan as far to your left as possible. It is not necessary to disconnect the electrical plug to the motor.

Drain the coolant.

The drain valve is located just below the bottom hose connection and the drain tube can be seen from underneath the engine just inside a ¾” hole. Place your container under the drain tube. It may be necessary to raise the car to fit your container. It may also be helpful to raise the car so you can work at a comfortable height (and save your back!).

Open the drain valve until you hear the coolant draining. The coolant will drain at a slow pace and opening the valve entirely will not speed this up.

When the coolant is drained completely, remove the upper radiator hose from the thermostat housing and push toward the back of the engine so it is out of the way.

Compress the GM hose clamp at the water pump connection and remove the hose. A small dribble of coolant might be present, so please have a rag handy to catch it.

Compress the GM hose clamp on the bottom and remove the hose entirely. Now you’ll understand why you needed to move those parts out of the way.

Remove the GM hose clamps from the defective hose and set aside as you measure the length of your new hose against the old. If there is a dramatic difference, cut the new hose to fit. Any saw with fine teeth will do this job nicely.

Install the GM clamps on the new hose and take care to position the clamps so it is easy to pull them onto the water pump (top) and radiator (bottom) connections when necessary. You could also choose the replace these clamps with 2” hose clamps to make the install easier. This depends how good you are with maneuvering the clamps, but it might be especially helpful for the bottom connection.

Once you have installed and secured the new radiator hose, reinstall everything else in reverse order of these directions.

Add your drained coolant back into the expansion tank.

Run engine until warm, check for leaks and after cooled down (next day) check coolant level and adjust as necessary.