coolant change questions

[migot]

Greetings: My folks have an 2005 caddy deville with a 4.6L engine. It is time (really past time) that the coolant should be changed. I have 2 gallons of dex-cool and a pack of GM coolant tabs from the caddy dealer. I was going to attempt to do this myself, but i am fighting cancer and am kinda weak. my folks are trying to conserve money. A local repair shop that specializes in heating and cooling services, says that they would drain the dex-cool, manually flush the system with a garden hose (he assures me the engine will not get too hot) and even use my 2 gallons of customer-supplied dex-cool and the coolant pellets. The price is decent.

1)Should I grind up the pellets for the shop beforehand and put them in a zip bag? The guys at the caddy parts shop said to pulverize the pellets before adding them to the coolant. I am afraid if I don't do it, that the guys will skip this step and put them in whole.

2)I read an old post on another board that said you cannot add pellets to the surge tank. This guy said to pull off a radiator hose and put them in there. Any thoughts on this? He did not say whether or not he ground up the pellets first or placed them in the radiator hose whole. If pellets are ground up to powder and added to the surge tank, won't they mix up with the dex-cool?

3)I have 2 gallons of dex-cool. The capacity is listed as 13 quarts. 13 qts./ 4 gives me 3.25 gallons. To get a minimum of 50% mixture, i divide 3.25/2=1.625 gallons. Or 1 5/8 gallons. Since there will still be some water remaining in the block, I figure even throwing in 2 gallons would NOT go over the maximum of 70% strength. The car is in SW Florida, we just had a low of 29 degrees even down here. Adding 2 gallons should be okay, correct?

Thanks for any advice. great site.

[JimD]

.... A local repair shop that specializes in heating and cooling services, says that they would drain the dex-cool, manually flush the system with a garden hose....

I would and do not flush with tap water. It is not necessary; there is no ferrous metal in the cooling system (other than the water pump cartridge and that is stainless steel).

2)I read an old post on another board that said you cannot add pellets to the surge tank. This guy said to pull off a radiator hose and put them in there. Any thoughts on this?

Both points are correct.

He did not say whether or not he ground up the pellets first or placed them in the radiator hose whole. If pellets are ground up to powder and added to the surge tank, won't they mix up with the dex-cool?

At the end of the day grinding to powder or not makes little difference; the water pump will do the grinding in a heart beat. Just DO NOT place the pellet material in the reservoir; place the material in a hose.

You will not be able to completely drain the cooling system. If the system is not flushed, whatever quantity of coolant remains in the block will be the proper ratio of Dexcool and water. The only unknown is - how much coolant remains.

Standard procedure is to drain as much as possible. That model vehicle will have a drain plug on the bottom surface of the radiator, LH side; you will have to remove a plastic trim piece to access the bottom of the radiator. Pull the large hose off the bottom fitting at the water pump, place pellet material in the hose, install hose, fill reservoir with mix of 50% Dexcool and 50% (distilled) water. Operate engine until temperature reaches normal guage position (usually 12 o'clock), stop engine and allow to cool. When cool, adjust the coolant level in the reservoir with your 50/50 mixture.

Done.

[Ranger]

GM no longer uses the sealant tabs. I'd forget them. I do not use them in my cars any longer. I believe they are the reason for clogged purge lines and heater cores. Just my $.02

[migot]

Thanks for all the tips guys, I appreciate it. In conclusion:

1)You shouldn't worry then about flushing the coolant system on a late-model (2005) Deville 4.6L? I am confused about that part. I just read someplace again that if you just drain the coolant, lots of coolant will remain in the block. Some site, (arrowhead radiators, I think) says that is why you should have a coolant exchange machine do the job. It gets out all the old coolant plus any air pockets. So, which is better? 1)Just drain the old coolant and fill with new dex-cool and monitor the level over the first couple weeks?

2)Use a shop with a coolant exchange machine?

3)Use this one shop where the guy says he prefers to flush the system with a garden hose?

4)Try to do it myself (if feeling well enough). I would put it up on ramps. Drain system. Fill with spring water (as we have hard water here). Get engine hot, then drain,. Fill with spring water, get hot, then drain. Fill with 2 gallons of dex-cool and distilled water. This last procedure I thought was the best for getting out the old coolant if you are doing it yourself at home. Unfortunately, the shops that don't have a coolant exchange machine, just drain and fill. They don't have all the time it would require to keep going out and refilling and draining the cooling system.

5)Are most of you in agreement that the newer caddy's don't need the cooling pellets? I called up a guy this morning who just works on caddys in a private garage. he said that the pellets were mainly for the 4.1, 4.5, and 4.9 liter engine which had problems with the intake manifolds. He sort of hedged on his answer on whether or not the pellets address other problems such as metal porosity in various parts of the engine. When i told him i had already bought the pellets, he told me if I brought it to him, he would either put them in or leave them out, it was up to me. i forgot to ask him (if in his opinion), the newer caddy's needed them. The last poster on this thread believes that they may plug things up? Any other thoughts?

Thanks, Michael

[JimD]

....The last poster on this thread believes that they may plug things up? Any other thoughts? Thanks as always. michael

Ranger and I have agreed to disagree about the pellet material.

My '98 has a decal under the hood that calls for the pellet material by part number. There is also a note in my Owners Manual to the effect that the pellet material be used. At some point in production, Cadillac stopped installing the pellets in new engines.

My guess is dealers were hearing complaints about the "brown crud" that shows up in the reservoir after a few thousand miles. Car owners were worried about it. Needlessly. I see the 'brown crud" as evidence that there is at least enough pellet material in the cooling system to stop/prevent minor nuisance leaks. And there is a lot of "brown crud" in my reservoir. It's harmless.

[KHE]

Just drain the system, install the pellets in the lower radiator hose, and refill with fresh Dexcool mixed 50/50 with DISTILLED water. Do not add "spring water" or any tap water to the system.

[Ranger]

The reason we say not to flush it is as you said, you can't get all the old coolant out. If you flush it, you won't get all the water out and will have a hell of a time getting a 50/50 mix. An exchange machine will do it if you want to pay the price.

Jim, you are correct about the tabs. I have heard of people with plugged purge lines and heater cores and I am pretty sure (over time) it is from the tabs. What made me stop using them is when I did a coolant change on my wifes '96 Bonneville (3800). The cap was so clogged with that residue crap that I was surprised that it even worked any more. That's when I swore off of them. Won't hurt to use them, but that's my story and I'm stick'in to it.