: Flushing Radiator



speedydog
10-28-07, 12:24 PM
just picked up a 2001 STS i wanted to flush radiator how do i do it (pull hose off or should i run car with radiator drain open and hose in tank???

CadillacSTS42005
10-28-07, 12:42 PM
nope
put the car on jacks
remove the huge splash shield, its held up by about 10 push pins)
on the back of the rad (the side that faces the fans) on the drivers side theres a screw
twist it, it will open up the rad
drain it and then fill

Submariner409
10-28-07, 12:55 PM
If you drain it using the radiator tap it will take forever and you won't get most of the coolant out anyway.

Your manual recommends DEX-COOL and 3 of the Bar's tablets, crushed in the lower hose. Look in the owners manual for capacities, and take that with a grain of salt.....Also, 2 or 3 quarts of coolant will remain in the block as there are no block drain cocks.

So, warm it up, place it on ramps (watch out for the front bumper skirt) or jack it up and place jackstands, let it cool a bit, remove the air deflector (10-12 plastic rivets, dealer, .60 ea.) and pull the lower hose off the lower radiator spigot carefully. (Bust the aluminum radiator = unhappy camper). Some coolant will remain in the surge tank, so flush it with a hose....the water will slowly drain out the lower tank hose, through the bypass and pump to the lower radiator.

Mix up a couple of gallons of 60/40 DEX-COOL and water (distilled, if you're anal). Crush 3 Bar's/GM supplement tablets (ONLY tablets...no liquids) obtained from your dealer, cheap, or a large parts store, cheaper. Place the mess in the lower hose and reinstall it with the clamp in the same place as before (dents in hose). Funnel in as much of the coolant mix as possible, filling the surge tank to the COLD arrow indicator on the front side. Leave the tank cap off. Start, warm up, and check for leaks. Let it idle for 10 minutes while you watch the level in the surge tank. You should see spurts and bubbles come from the bleeder hose. When all seems well, reinstall the air deflector and lower the car. Let it cool and return the coolant to the level indicator on the tank. Dispose of the old coolant - it's poison. Go for a short drive and once again, check the coolant level.

An afternoon's work to do it properly. OR, you can look for a GM dealer winterization special and have someone to jump on in the event something doesn't go right........Your call, but DIY will teach you a lot about the car and just where the oil filter setup is..........

speedydog
10-28-07, 12:55 PM
but that will only drain radiator how do i flush the whole system?

CadillacSTS42005
10-28-07, 01:03 PM
run a hose through the upper hose
completely unnecessary though...

and as long as you remove the upper rad cap it doesnt take FOREVER to use the rad drain plus its safer (its not fun or easy to pull the lower rad hose as it uses a tensioned clamp not a screw one)
it took about 10 mins through the screw, obviously its faster to drain through the lower rad hose but the added time it takes to pull that hose plus the risk, its just not worth it...

Ranger
10-28-07, 01:16 PM
Why do you think you need to flush it? Stick a garden hose in it and your adding all sorts of unwanted minerals (Chlorine, calcium, lime, iron etc). You won't get it all out. Just drain it and refill with 50/50 Dex/distilled water.

dkozloski
10-28-07, 01:40 PM
The object of the exercise is not to flush out poop like a toilet but rather to renew the corrosion prevention chemistry. Draining the old coolant makes room for new coolant with fresh corrosion prevention chemicals. Some of the old coolant remains behind as the system does not drain completely but it is of no consequence.

Submariner409
10-28-07, 01:59 PM
Granted, pulling the lower hose is a hassle, BUT his FSM calls for the Bar's tablets in the lower hose. (So does the '02 copy....) Either the drain tap or lower hose drains as much of the system as possible without backblowing with air.

If you don't do the whole recommended procedure, why do it at all?

Speedydog, before you start this exercise, spend a couple of hours in here searching for coolant threads and some of the techniques and workarounds that other owners have come up with. There's no mystery, just food for thought.

CadillacSTS42005
10-28-07, 02:02 PM
ahh true
i neglected to remember that about the tablets....
i put one in the upper then another the next mth after a swap...

Submariner409
10-28-07, 03:00 PM
Speedydog......I just caught a "mistake" in some of our advice. There is no "lower radiator hose" as we would commonly call it in this Cadillac series of cars. The hose we all refer to as "lower" or bottom of radiator isn't there, it's halfway up the left tank, feeds directly into the water pump housing, and the FSM calls it an outlet hose, while still calling it "lower" in the refill and tablet installation paragraph.

Therefore 2003's caution about the drain cock is right on.

Sorry..............

Old habits die hard...........

codewize
10-28-07, 03:15 PM
DON'T. Just don't flush a N* system, ever.

For one you'll do more damage than good and secondly you'll totally loose control of the precise 50/50 mix in the system. Once you do that, it's all down hill




but that will only drain radiator how do i flush the whole system?

Submariner409
10-28-07, 03:45 PM
codewize........Perplexing statement ^^ (precise 50/50 mix)

The '02 FSM states "a mix preventing freezing to at least -34F" and "a mix no greater than 70/30"...(as pure DEX-COOL freezes at -8F).

A DEX-COOL jug states that a 50/50 mix is good to -37F, while 70/30 (the max Cadillac recommends) is good to -84F.

Taken to extremes, Cadillac therefore recommends a mix between 48/52 and 70/30.

Hardly precise.

(Speedydog, see what a simple question can do to a bunch of gearheads?)

codewize
10-28-07, 04:30 PM
Hmm Well I will say that I was under the impression that we wanted to be as close to 50/50 as possible. I guess that's good news for most of us, but even so, if you flush the system you really have no idea what the ratio is afterwards.

You've got some unknown quantity of water in there, tap water at that and now you're going to add what, pure antifreeze until it's full? I don't like the idea and I can definitely see 100 reasons why it's better NOT to flush the system.

I do have a question, what does it say in the manual? Not to flush but to drain and refill? Or does it just say service the coolant or something? I personally see no reason to flush and if there is a reason you're probably better off replacing the radiator.


codewize........Perplexing statement ^^ (precise 50/50 mix)

The '02 FSM states "a mix preventing freezing to at least -34F" and "a mix no greater than 70/30"...(as pure DEX-COOL freezes at -8F).

A DEX-COOL jug states that a 50/50 mix is good to -37F, while 70/30 (the max Cadillac recommends) is good to -84F.

Taken to extremes, Cadillac therefore recommends a mix between 48/52 and 70/30.

Hardly precise.

(Speedydog, see what a simple question can do to a bunch of gearheads?)

Submariner409
10-28-07, 05:15 PM
CODE.......Here's THE flushing quote from Cadillac, p. 6-650, Engine Cooling, '02 Seville.

"Flushing
Important: The thermostat should be removed before flushing the system.
Various methods and equipment may be used to flush the system. If using special equipment such as a back flusher, follow the manufacturer's recommendations."

Thats IT. Nothing else. Doesn't give one a lot to hang your hat on, does it? Flushing is not mentioned in any cooling system part(s) replacement either.

RE: Your second sentence ^^. IF you flush with water, and then refill with 60/40, you'll be darn close to 50/50 at the end. After a few days you could adjust the mix by sampling with an antifreeze hydrometer, drawing off some coolant from the tank, and adjust with either water or DEX-COOL. (anal....)

CadillacSTS42005
10-28-07, 08:01 PM
Speedydog......I just caught a "mistake" in some of our advice. There is no "lower radiator hose" as we would commonly call it in this Cadillac series of cars. The hose we all refer to as "lower" or bottom of radiator isn't there, it's halfway up the left tank, feeds directly into the water pump housing, and the FSM calls it an outlet hose, while still calling it "lower" in the refill and tablet installation paragraph.

Therefore 2003's caution about the drain cock is right on.

Sorry..............

Old habits die hard...........

lol no prob sub
nothing but love all around ahhaha

codewize
10-28-07, 09:36 PM
Hmm weird. Ok so I guess you could flush if you wanted to but why? Why would you want to introduce tap water into the system? :o

Sometimes I wonder if this is an automotive board, science or math board. LOL. Either way it's a bunch of fun at any given time :yup:


CODE.......Here's THE flushing quote from Cadillac, p. 6-650, Engine Cooling, '02 Seville.

"Flushing
Important: The thermostat should be removed before flushing the system.
Various methods and equipment may be used to flush the system. If using special equipment such as a back flusher, follow the manufacturer's recommendations."

Thats IT. Nothing else. Doesn't give one a lot to hang your hat on, does it? Flushing is not mentioned in any cooling system part(s) replacement either.

RE: Your second sentence ^^. IF you flush with water, and then refill with 60/40, you'll be darn close to 50/50 at the end. After a few days you could adjust the mix by sampling with an antifreeze hydrometer, drawing off some coolant from the tank, and adjust with either water or DEX-COOL. (anal....)

Submariner409
10-28-07, 09:57 PM
Automotive, science, math...........It's all 3, and as the movie song goes ".....you can't have one without the other.........."

Poor Speedydog.........

SpiritF4
11-05-07, 02:43 PM
Re: '94 N* STS:
1. Drain n refill vs flush n refill ?
2. draincock vs remove "lower hose"
Thanks for the help folks.
SpiritF4

Ranger
11-05-07, 05:17 PM
Drain & refill.
Drain plug is the lowest point. I would recommend using it.