Flushing cooling system on GMC Savanna.........

Ok...same 99 Gmc Savanna 5.7l as usual...now I just finished changing the intake manifold gaskets, and I figure I'll scab up enough tonight to undertake the coolant flushing tomorrow...Question is a friend suggested vinegar as a flushing agent...Any pro's or cons will be appreciated...I just planned on filling with water getting to temp...draining a few times...thanks in advance ...

Reply to
Peter Griffin
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I wouldn't waste my time with vinegar. It isn't acidic enough to really do any good with respect to any iron oxide that may be in the system... at least over the short term. And if you dont get it completely washed out, it could offset some of the corrosion protection you might expect from your coolant corrosion inhibitor package.

The idea isn't totally off base, just too weak to be effective.

Reply to
<HLS

not do concerned with the corrosion, more about the dex cool coolant mixing with the residule in block

Reply to
Peter Griffin

The reason you have products like DexCool and other prepared coolant formulations is to offset corrosion in the block and radiator.....ordinary ethylene glycol or propylene glycol work perfectly well as antifreezes and coolants without any sort of proprietary chemical additives.

I am not sure that that fact has been stated often or is clearly understood.

Yes, you want to get the block and radiator as clean as possible, and a thorough water flush is about as good as you can do it. The vinegar is not really going to help you.

And if you drop the pH of the OAT DexCool, you will convert the organic salts (which are extremely water soluble) into organic acids. These acids are not very soluble, and will scum out in the block and radiator.

When I do this job, I normally remove the thermostat, and flush repeatedly through the block and through the radiator until everything runs clean. (and replace the thermostat with a new one when I am finished.)

Your vehicle is now approaching 6-7 years old. If you have not replaced hoses before, this could be a good time to do it. It is hard to predict when they are likely to fail, but 5 years, 100,000 miles, is certainly getting into the zone where a replacement wouldnt hurt.

Reply to
<HLS

While doing the intake gasket set, I also did the serpentine belt, and inspected/cleanes everything...The hoses seemed fine, but The thermostat is a good idea, somehow I overlooked it, probably too concerned with labeling all plugs/bolts, and cleaning up all the blood from scrapes....should of just yanked the engine/trans instead of doing the intake in the van :( also noticed upper rad hose is seaping now....think it is the disposable clamps they use now..........

Reply to
Peter Griffin

I know what you mean about scraped knuckles.

Removing the thermostat allows you to flush the block thoroughly, whereas you may have an impossible time to do it otherwise.

Lots of people here use only the spring clamps which often come as OEM. They work fine, usually, and are certainly preferred to low quality screw clamps. I also use high quality screw clamps and don't have any particular trouble.

Reply to
<HLS

Here is how I did my last coolant flush,

1) Opened radiator drain petcock fully 2) Disconnected one of the heater hoses going to the heater core at the firewall 3) Opened radiator cap. 4) Waited until all coolant drained. 5) Inserted garden hose to overflow bottle cap and held hand around hose and cap, turned on water half pressure until clear water running from overflow host to radiator. 5) Inserted garden host to rad cap and wrapped a rag around the area, held rag on with hand. 6) Turned on garden hose full until water running from petcock, heater, host to heater was running clear, about 5 minutes. 7) let system drain. 8) closed everything up, poured in full bottle of antifreeze, not diluted. 9) Filed remaining with 50/50 antifreeze and water. Ran car and topped off when it burped, then drove car and over the next few days using a antifreeze tester, added antifreeze and mixture until cooling system completely full.

Ted

Reply to
Toyota Questioner

A GM powertrain engineer who used to post on a Caddy board cautioned that flushing is not necessary unless you have a clog of some sort. His suggestion was to just drain the rad and refill with 50% distilled water and 50% coolant, in this case probably Dexcool. The idea is not to introduce tap water with it's mineral content into the system. FWIW YMMV

Reply to
NickySantoro

Depends. I wince at generalizations like the one the PTE has made.

If you have a lot of iron oxide (rust) in the system, then I believe it is best to wash it out. Iron oxide is a powerful adsorber of polar chemicals such as are in the antifreeze packages. The result can be a puttylike mess.

Deposits, including iron oxide, on metal surfaces can be a prime cause of corrosion. And guess where the corrosion occurs...that's right, just where you wouldn't expect...it occurs UNDER the deposits. (I'm sure you've seen rusty tubercles form in iron systems exposed to water. Deposits can be a cause of this.)

If you live in an area where tap water is mineral laden, you might want to spend a buck or two a gallon to buy distilled water. It wont break you. We've discussed this before. Especially if you are using a silicate bearing coolant, it is best if the makeup water is rather pure.

In addition, the potential corrosion rate in water systems is related to the conductivity of the water, among other things. The more conductive (due to minerals) usually the more corrosive it is.

Where I live, the water comes from lakes and is not heavy in minerals. (or at least, it wasn't until the state changed the treatment program a short while ago).

Reply to
<HLS

That's how I did one once but I refilled the rad a with distilled water , ran the engine until it circulated and drained again, repeated a few times and then filled with ant-freeze.

Reply to
Ken Hilson

That's simple. Flush with straight water first (fill, start, warm up so water circulates, shut down, and drain immediately. Then throw away any DexCool you have, and put in Ford or Mopar G-05 coolant instead. And use distilled water.

Reply to
Steve

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