: Coolant Drain and Fill Procedure for 1998-2004 Seville



Kaline
07-14-09, 09:31 AM
Attached is the official GM engine coolant drain and fill procedure for a 1999 Seville, as downloaded from the GM Service Information website. I would expect it is the same for all 1998-2004 Seville.

Loose screw
11-22-09, 11:52 PM
I followed the draining procedure as I was trying a headgasket sealer and needed to flush the collant system and also leave the engine without collant for a few days for the product to cure (dry) I ended up with the freeze plug behind the water pump poping out over night (it got cold) on my 99 STS. Some water was obviously still trapped. I recomend blowing air through the engine to help get all the water or coolant out. Pulling the drain plug in the radiator and removing a few hoses to let it drain was NOT good enough! The freeze plug is almost impossible to get to without removing the cross over but I was actually able to get it in after many attempts. Note: the freeze plug is not all the way in and seated when it is flush with the surface of the engine. It must be forced in an additional 1/16 from the surface. I used a varity of tools to push the freeze plug in evenly on all sides rather than tap it in with a hamer and socket (or proper installing tool). It is very hard to get the top of the plug in far enough due to the angle that the watter lump and cross over force your tools to be at to even touch the plug, but it can be done!

rabird
11-27-09, 05:41 PM
What is a good tool to use to stick through the hole under the vehicle to loosen or turn the drain plug?

Loose screw
11-28-09, 12:52 PM
The standard factory drain plug allows the use of a socket, best used with an extension

SevillainSTS
12-04-09, 10:02 PM
they say not to use the pellets anymore right?

mikec35
03-27-10, 11:09 AM
Does anyone know if you are supposed to use the pellets anymore? Thanks

Submariner409
03-31-10, 07:37 AM
Current guidance says if there were no nuisance leaks before the coolant change, no reason to use the Bar's tablets (product HDC) or powder (product G12BP).

Loumar1684
06-05-13, 11:35 PM
Hew to this site... looking for tips on replacing the coolant on a 2000 DeVIlle. I drained the radiator and keep replacing the coolant with distilled water. Used about four gallons of it. I never found the radiator cap. I kept filling the overflow tank finally I poured about 1/2 gallon of the Dex 50/50 coolant. the instrument panel shows low coolant level...Spent about 2 hours doing this. Should I have tried to remove the shroud above the radiator? The instructions I read here on this site did not say anything about the shroud, so I left it alone. Like I said, I'm new at this.
Help anyone ?? Thanks

I used a 3/4" short socket with an extension... much easier

Submariner409
06-09-13, 08:27 AM
Now drain out all the water you poured in (there is NO "radiator cap") and replace the water with a 50/50 mix of whatever coolant and distilled water you like.

Before you begin, it's obvious that you didn't study the Northstar cooling system or how to properly fill/bleed it. Go the the sticky posts in the Engines, Northstar performance forum and read up on cooling system procedures. Then go way up ^^^ in the top black bar and read up on clloing system maintenance in the Cadillac Technical Archive. (Matter of fact, read up on all your engine stuff in the Archive - there's info in there that you may not know ........)

To make 2 gallons of 50/50 coolant - one gallon of pure coolant, one galon of distilled water (supermarket) and a 2 quart pitcher. Pour half the water into the pitcher. Refill the water jug with raw coolant. Pour the pitcher of water into the coolant jug. You now have 2 gallons of proper mix coolant and a clean pitcher.

AFTER your drain-fill process, the proper coolant level in the reservoir is half full - checked cold ONLY. Never check or "top up" coolant when warm or hot. Cold only.

Please study up on proper procedures for these cars - it's really easy to break something and cost yourself some big bucks in the process.

Loose screw
06-10-13, 01:35 PM
Hew to this site... looking for tips on replacing the coolant on a 2000 DeVIlle. I drained the radiator and keep replacing the coolant with distilled water. Used about four gallons of it. I never found the radiator cap. I kept filling the overflow tank finally I poured about 1/2 gallon of the Dex 50/50 coolant. the instrument panel shows low coolant level...Spent about 2 hours doing this. Should I have tried to remove the shroud above the radiator? The instructions I read here on this site did not say anything about the shroud, so I left it alone. Like I said, I'm new at this.
Help anyone ?? Thanks

I used a 3/4" short socket with an extension... much easier

There is no radiator cap. The tanks is part of the pressurized cooling system and is the correct location to fill the radiator/cooling system.. If you have steam out the exhaust and or can't get and keep the tank to stay full (tank should not be fill to top, there is a mark inside) and can't find a leak you have a head gasket leak and or head bolt thread failure both are very common on these engines. Coolant can leak into the cylinders and get used up. Also Highly pressurized air can leak into the cooling system and over pressurize it and force coolant out of the tank. Also check for water in the oil - look for gray oil, blocks can crack and leak collant into oil. :-(

Ranger
06-10-13, 11:03 PM
Water in the oil on a Northstar is as rare as hens teeth.