How do you change radiator coolant on a 1997 Cadillac De Ville with a North Star engine?

Answer 1

There are a number of "vehicle geometry" issues mentioned here. If you want the short answer to the question as stated, see the bullet near the end. The difficulty lies in the fact that there is no really direct route from the petcock - which is near the bottom, driver-side, inboard, face of the radiator - to a receptacle beneath the vehicle. (If you didn't know where it was - it is not your fault. It is well-concealed from above by other connections to the radiator. You can find it, but you need to know where it is first... ;-)) ) [I don't recall if draining via the petcock is blocked by the sheet metal panel at the bottom or not. (I am all but certain that it is blocked in this way - Otherwise, I would have found this operation easier...) You will need to remove from the bottom of the vehicle: a (full radiator width) plastic panel having three hex-head screw fasteners; and the driver-side connections of a 'hardware-paper'-ish sheet of material attached to the body from below, by a number of plastic press-together, two-piece fasteners - in order for you to have a shot at the petcock from that direction. I opted to remove the fasteners non-destructively, as the OEM parts are never cheap (sometimes similar fasteners can be found at auto parts stores). In addition, I suggest that you not expose that 'hardware-paper' item to any more antifreeze that is absolutely necessary. (It will sag, and be difficult to keep in place after such exposure.)] You may be able to attach a rubber hose to the petcock, and use it to drain to a container, but I chose to put a big round plastic 'pan' underneath. [Even if you use a plastic tube, you still need to be able to open the petcock - Not easy!] To open the petcock from above (standing - facing the vehicle), you probably need to find someone with hands the size of a three-year-old's; those same hands possessing the strength of an adult male; and arms the length of a person 6'9" tall! (I really wish I was joking about those 'specs'...) The petcock is very hard to reach, and in the end, I chose to do it 'brute-force'. I placed a pan underneath, and disconnected the lower radiator hose. I don't believe that there is a realistic non-messy option - Although I expect that this was the hope of the question. I am unaware of a tool that is designed specifically to open the petcock from far above, but if one exists it would have two prongs in the horizontal plane, and the ability to control their rotation about the horizontal axis, by actuating the turning from a distance of about 24"-30" in the vertical direction. [If you have a pair of 14"+ needle nose pliers, you might be able to place the jaws on either side of the petcock and twist it open (assuming they don't break). (Get under the vehicle, and bring the pliers in from 'vehicle-rear', perpendicular to the intended direction of twist.) In my case, the petcock was so tight, that it took a pair of channel-locks after removal of the radiator!] A cleaner approach might be to pump the fluid from the reservoir with the engine running, but I don't know how much fluid you could remove that way either? (And some of it will be hot - Not so safe!) * I vote for removal of the radiator hoses but only after removal of the under-body fabric! Get a wide pan and let it fall through. It's dirty, but I didn't have a week to get the petcock opened... ;-))