Cooling System Flush

[GMCfourX4]

I'm about to flush/replace the DexCool in my cooling system, but I have a couple questions. I have a small leak from the metal coolant pipe? (for lack of a better word) which runs from the front/center of the enging towards the back on the passenger side. I believe the leak is just the O-ring or whatever it is. What I want to do is perform a full flush of the system, and replace all of the hoses. I would also like to replace any of these seals that may be leaking, and I was wondering if there was a "kit" of something GM has with all of these items. I would also appreciate input from people who have done a full flush of the system (are there block drains I should use, any idea how much water stays in the system, what kind of flush should I use, etc?)
Thanks in advance,

-Chris

[StephenA]

Me too, me too, -I gotta flush mine too & have no idea. Is this something I can do with my garden hose & an attachment & some flush? I ave about 80 psi in the hose (pops hoses if I leave them on).

[cruzer]

Don't really know how your going to flush the engine, but you do need to use DISTILLED water. I'd pull the rad and backflush w/Diss water. Clean the fins. Spray the A/C condensor from inside out and try to get between condensor and oil coolers. You need to get all the bugs and debris out.Maybe some else can chime in on ideas to flush the block. Tap water has tooo many different chemicals in it that react to the
dexcool.

[StephenA]

Hey cruzer Hmmm... so what, 20, 30 gallons of distilled under pressure? Do I add any kind of flushing agent? I was going to have a rad shop do it for $40. What do they use? Could I do a better job myself? Use distilled to flush the rad too?

[cruzer]

I don't really know. When I did mine it cost thousands of dollars. Cracked piston, new rad cooling mods and everything else listed below. Heat and Improper maintence eventually took its toll. I maintained it like it was a gas motor.

My block was clean when I got it back from machine shop. I washed w/soapy distilled water and rinsed and rinsed and etc. On these engines, proper cooling maintance is a must. When I service my cooling system, I'm going to do it every 1 to 1 1/2yrs. I'll pull rad and back flush w/diss water(couple of gallons 4 maybe more), probably pour water in the bottom of rad shake around as to loosen sediment in bottom and pour out bottom. Then fill rad while laying flat w/cap on pour water in bottom outlet and let drain out the top outlet & cap. Maybe do that a couple of times.(backflush), spray for bugs and add new coolant and diss water. I'm sure other members have good ideas on this too. I maybe all wrong on this procedure. I think if you maintain regularly the block will take care of itself.

I was just letting you know distilled water is a must. See what the pro's do. I would stay away from pressurized cooling system cleaning. I've seen them used where the put the system under approx 14lbs of pressure. They are known to shorten the life of the waterpump. Too much pressure on the seal. my 3cts

[CareyWeber]

If you are flushing it and the truck has many miles on it replace the block heater at the same time IMHO. ;)

Carey

[cruzer]

If you replace the blk heater it will be easier to
flush the blk. Don't mix green coolant w/Dex.

[StephenA]

Thanks guys!

[ucdavis]

FWIW, from the reports on "permanent" anti-freeze types, there is no reason to flush once a clean system is filled w/the DexCool type coolant & distilled water mix. This has, for all practical purposes, resolved build-up in radiators/blocks/heater cores. Flush & replace @ ~150,000 miles.

[StephenA]

Really! What mix of Dexcool & dist H2O? 50/50?

[CareyWeber]

I used a 50 - 50 Dexcool/Distilled water mix when I did mine last year.

By the way 97's had dexcool from the factory and my radiator was clean on the inside with 120K miles on it.

Carey

[StephenA]

That's good news. Say how does dexcool compare with the waterless stuff like Greg sells on his Amsoil site- www.lubespecialist.com (http://www.lubespecialist.com) ? WHat's the best brand of dexcool or is there just one?

[cruzer]

"from the reports" I got too much $ in mine. I'll stick to my plan on service. They started using in 97? The reports of law suits started this yr didn't they?

[StephenA]

Hi cruzer. Do you use dexcool as well as the maintenance program? One thing about maitenance such as your doing: you certainly can't go wrong, and visual inspection will show exactly what's there. If I lost my engine to overheating, I'd flush it regularly too. I haven't lost anything thus far, but to insure I don't, I'm going big on maintenance. Doing all my own lubing, scoping the cylinders, compression checks, etc., & all of the work I don't need a machine shop for. I have to bone up on a ton of stuff, but it really pays to understand your own truck. Besides, I enjoy it. Just my 1.5 cents...

[Bobbie Martin]

I don't know when they started using DexCool, but our 95 Suburban came from the factory with it. I just changed it this year when I did the water pump. Everything looked clean. No problems ever with it.

[GMCfourX4]

I have read a number of things about both the waterless "Evans" NPG+ coolant and the Dexcool. Seems the issues with corrosion and other problems with Dexcool only occur when air is introduced into the system, which doesn't happen is a properly maintained cooling system. It seems to be a problem in the 4.3L v6s, but I haven't heard of anything like that with the diesels. The Evans NPG+ is supposed to be really good stuff, and I've found a large variety of people/vehicles who swear by it (everything from large OTR trucks to dirt bikes). I was seriously thinking about putting it in my truck, but I have no cooling issues, and its significantly more $$$ (keep in mind that its $21/gallon, and you need to put it in straight, so you have to have twice as much). I bought the Flex-A-Lite dual electric fans (similar to the ones MikeC has on his sub, but the newer version which flows 5500 CFM) and I'm going to stick with the Dexcool when I do the flush this weekend. If I do end up deciding to go with Evans, I'll do it later on down the road. I went to the stealership last night to get an o-ring for the coolant tube running back from the t-stat housing, and they list it as a non serviceable part. Anyone replaced this before? What did you use? I guess I'm just going to get an assortment of O-rings, and find one that fits (its leaking VERY slightly). What's the current wisdom on T-stats? What seem to be the best brands? I'm going to be sticking with the 195* stats.

-Chris

[damork]

My 95 came with the green stuff. Here is my sequence starting with cool engine:

1.Drain as much as possible facing downhill - helps to drain block.
2.Pull the thermostat(s) and reinstall cover with no thermostats in place (or remove thermostat center and reinstall to hold seals in place).
3.Refill with distilled water (facing uphill now to help fill block), run the engine just to circulate some - you don't need to warm it up with open thermostat passages.
4.Facing downhill drain again.
5.Facing uphill - refill with distilled, run to circulate.
6.Facing downhill drain again.
7. Repeat until clear water is all you see in a white drain bucket.
I believe I refilled and drained mine 3 times before the green cleared when I converted, or approximately 18-20 gallons of distilled water.

I ran the truck 18 months after the conversion then upgraded the water pummp to the HO system and when opened up the system it was like new, no sludge or goo of any kind.

When refilling it is very important to bleed the system a couple of times to ensure there are no trapped air bubbles. I went 50/50 Dexcool to distilled ratio.