Coolant Change Procedure

[Rollingon]

It's time for a coolant change on my '02 and I'd like to do it myself but I don't know the procedure to use. The first hurdle is how to drain the old coolant, and then to put in the new. I would appreciate any words of wisdom on how to do this. Apparently there was some info here on this 3-4 years ago but I couldn't find anything in the archives.

Thanks

[NutNbutGMC]

Found this, although not much to go on.

http://www.thedieselpageforums.com/t...hlight=coolant

The Helms service manual has a full detailed procedure.

[tbrowne]

I'm not sure which forum I read this on, but one poster suggested that the easiest way to flush the system was to knock out the freeze plugs on the engine block, flush, reinstall new freeze plugs and refill with fresh antifreeze. I'm not sure how difficult the freeze plugs are to reach, but they must be accessible with the fender well liners removed. Someone else may be able to comment on this procedure. I haven't tried it myself, but it does seem feasible.

[DmaxMaverick]

The block has threaded drain plugs at the bottom of the block. Do not knock out any freeze plugs.

Flushing the Duramax is nothing special, compared to any other engine. Open all the drains and collect the waste. Replace the plugs and fill with distilled water and flush (run up to operating temp a couple times). Drain again and repeat. Once it has been flushed to your satisfaction (all will be different, as with all engines), secure the drains and fill with 50/50 coolant and distilled water (or use premix). Bleed according to the procedure in the manual. Please note: Using flushing solvents or non-distilled water will have long term negative effects. At the least, ELC will not be as effective as long, and coolant system component life may be greatly reduced. The cooling system should only be flushed with fresh distilled water.

[Rollingon]

Thanks everyone for all the good info. I think I'll try to do it myself.

I am interested as to why to use distilled water for flushing and diluting. Not to challenge the wisdom of those who have much more knowledge than I do, but my Duramax (owners) manual says just to use "clean, drinkable water".

[DmaxMaverick]

All water, but distilled, contains minerals, salts, and possibly chemicals. Not good in the long run in a system made up of various metals. Minerals also promote outgassing (cavitation) and surface tension (slows heat transfer) of the fluid.

[conway]

Dmax:
Are you suggesting that dexcool not be used?

[DmaxMaverick]

Dmax:
Are you suggesting that dexcool not be used?

I was hoping to avoid that discussion (argument). I recommend using Dexcool in most cases. Some do not. Argument is pointless when it is based on "opinion" and personal experience. If you plan on changing your coolant often, use traditional coolant if you wish. If you want to take advantage of ELC's, use Dexcool. The advantages of using Dexcool become less on higher mileage engines. Failure of other components will usually require coolant replacement more often than the recommended change interval, anyway. Both coolants are similarly priced, so there is little, if any, monetary advantage to use either, except longer service (fewer changes). A healthy and properly maintained cooling system (and engine) will see a benefit using Dexcool. If you are uncomfortable with extended coolant service, just change it more often, regardless of the color. Used properly, though, Dexcool will "work as advertised". Problem is, most folks unknowingly don't use it properly. It's no more complicated than that, and I do not (will not) wish to engage in an argument as to which is better. It's your engine, you decide. The effects of water choice is the same, either way.

[Rollingon]

DmaxMaverick. you wrote "The block has threaded drain plugs at the bottom of the block". There are a number of hexhead bolts/plugs on the bottom of each side of the block. Which one(s) are the coolant drains? I sure don't want to be loosening any main bearing caps!

[DmaxMaverick]

The drain plugs (one on each side) are above the lower edge of the block, above the skirt (same as surface of the lower block, next to the freeze plug). The main crossbolts are horizontal. It's been a couple years since I've done one, but it's pretty simple. The plugs are individual, meaning there isn't a line of them, and nothing else connects to them. IIRC, they are near the front of the block. Torque them to 13 lb/ft.

I checked the GM manual for the coolant specification. It does state a 50/50 mix of Dexcool and clean, drinkable water, but also states right after, (preferably distilled). It also cautions that using silicated coolant (traditional green) will shorten the service interval (30K miles or 2 years, vs. 150K miles or 5 years), and could cause premature engine, radiator and heater core corrosion.