: 2002 Cadillac Deville Rad Flush tips?

01-10-09, 11:27 AM
Hello Cadillac community,
I got an 02 Deville, which is giving me a coolant low message, checked the surge tank and sure enough it was low. There appears to be some brown residue around the surge tank, which i assume is from the air and dex-cool. Is it suggested to do a flush? If so what's the best way of draining and flushing? Or should I just do a 50/50 mixture of dex-cool and water and poor it down as is? I also read about some of these tablets is that necessary for an 02 deville?
Sorry for the assault of questions and thanks for your time :)

01-10-09, 01:10 PM
The brown residue is from the sealant tabs. Just drain and refill 50/50 Dex and distilled water. GM stopped using the tabs so I would not use them unless there is a need. You can read all about them in the sticky in the Tech Tips section.

If you are loosing coolant, you have a leak somewhere. Dried Dex leaves a chalky whitish residue. Check the surge tank as well as the radiator side tanks. They have been known to crack. Also the crossover manifolds have been known to leak some.

01-10-09, 02:23 PM
Thanks for the advice and look outs Ranger, happy that the brown residue is just the sealant tabs, I'll check around for leaks at the two tanks, but Im a little confused as to what/where the crossover manifold is...also where is the drain plug/cap for the radiator fluid is it covered by the giant splash shield?

01-10-09, 06:19 PM
The crossover manifold is where the water pump resides. Since the intake manifold is dry (no coolant running through it) there has to be a means to get coolant from one head to the other. Thus the crossover.

The drain is on the lower left side of the radiator. There is a hole in the splash shield. Peek up in there and you'll see it. If you don't remove the shield, the easiest way to get at it is to cut a length of 3/4" dowel rod and then cut a slot in the end to fit over the drain plug. You'll see what I mean when you see the plug.

01-10-09, 07:21 PM
....and there is no radiator cap on top of the radiator. All fill work is done through the surge tank.........the 1" ID hose on the bottom of the tank floats on the cooling system.

01-11-09, 04:19 PM
There is a TSB for leaky water pump gasket and covers on 2001 and 2002 Northstars... Common problem, with another "updated" part. Mine leaked there too.. You will drive the car and smell coolant coming out of the front drivers wheel well... with no drips and no visable leaks, and if you know Northstars you will think that your head gasket it toast...

What happens is that the cover slowly drips coolant onto the trany bellhousing where it instantly evaporates (and stinks)... a new cover and gasket and more 10mm nuts and bolt then I care to mention later and the car will be like new. I did mine about 2 years ago I think the parts were less then $50.

04-24-09, 11:23 PM
Is there a air bleeding procedure to get the air out of the system?

04-25-09, 09:17 AM
Shops use a vacuum drain/refill system so there's no bleeding involved. The Northstar has a purge line which runs from the water pump discharge at the crossover to the top edge of the surge tank. It must be checked clear, as well as the 2 connector nipples, and the system filled as much as possible. Start the engine and coolant should constantly bleed from the purge line: Air and gasses remain in the surge tank airspace (half to 2/3 full, HOT) and the small amount of purge coolant returns to the system via the lower surge tank connector hose. There is no great flow through the surge tank: it is only an expansion chamber.