Using distilled water with your coolant?

[Ironheadziggy76]

Hey all,
I'm sure everyone already knows this but I thought I would pass it on anyway. I had to replace an intake manifold gasket on my 96 Chevy truck a couple of weeks back and I noticed something a little disturbing. Other than the lame design of the water passages which probably caused the gasket failure, I noticed a LOT of corrosion on the aluminum thermostat gooseneck where the top hose connects. I don't see how the hose wasn't leaking from all of this. Then I got to thinking about my stupidity. I replaced a water pump a couple of years ago and in my haste to get it on the road, I mixed the coolant with water from the garden hose instead of using distilled water. I have always read this was a no-no with aluminum engine parts, now I know for sure. I was reading the post about silicone in the bars and it reminded me about this. I had several mechanics tell me that the red Dex-Cool antifreeze GM uses is very hard on gaskets and they recommend replacing it with the normal green stuff in GM products.

I was pleased to see the engine was very clean inside, due I guess to frequent oil changes with Mobil 1. So if you are changing coolant remember to use distilled water with your coolant if you don't buy premix!

[Clamper]

I always use pre-mixed, and they use distilled water. In the 60's working in a Gas station, we used distilled in batteries. The Machanic would always drink the distilled as it tasted better than the city water and pretty soon we all did. The owner finely started buying regular bottled water for us to drink, as the distilled costs more than regular drinking water.

[coopdway]

I use the pre-mix from Honda since I just don't go through enough of it to justify bigger quantities of concentrate.

[Flashdog]

The big reason to use distilled water in an engine is to protect it from minerals coming out of solution and blocking smaller water passages. Most municipalities today either purify the water supply by reverse osmosis or distillation. The water is flat and tasteless. They then add minerals and salts to give it a bit of a kick. There's not normally enough dissolved solids though to create an issue with corrosion or blockages in engines. Plus, the anti-freeze/coolant mixed with it should have corrosion inhibitors in it anyway.

As for the corrosion in the thermostat housing, that can be caused by electrolysis due to the use of dissimilar metals and not being properly bonded. The thermostat housing may be isolated from the rest of the engine because of the gaskets and hoses. This can be tested with a multimeter. The housing may be acting as a sacrificial anode. Try bonding the housing to the engine block or frame by attaching a piece of wire between the two.

That said, I would still use either distilled water or premix.

[Yamifj1200]

The big reason to use distilled water in an engine is to protect it from minerals coming out of solution and blocking smaller water passages. Most municipalities today either purify the water supply by reverse osmosis or distillation. The water is flat and tasteless. They then add minerals and salts to give it a bit of a kick. There's not normally enough dissolved solids though to create an issue with corrosion or blockages in engines. Plus, the anti-freeze/coolant mixed with it should have corrosion inhibitors in it anyway.

As for the corrosion in the thermostat housing, that can be caused by electrolysis due to the use of dissimilar metals and not being properly bonded. The thermostat housing may be isolated from the rest of the engine because of the gaskets and hoses. This can be tested with a multimeter. The housing may be acting as a sacrificial anode. Try bonding the housing to the engine block or frame by attaching a piece of wire between the two.

That said, I would still use either distilled water or premix.

Steve wouldnt the thermostat housing be grounded to the block with the bolts that hold it in place?? Just thinking out loud??

Eric

[Flashdog]

Not always. Nylon washers, Nylock nuts, and gaskets can be insulators. I used to be a merchant marine engineer for over 13 years and saw this type of thing quite often.

[Ironheadziggy76]

As for the corrosion in the thermostat housing, that can be caused by electrolysis due to the use of dissimilar metals and not being properly bonded. The thermostat housing may be isolated from the rest of the engine because of the gaskets and hoses. This can be tested with a multimeter. The housing may be acting as a sacrificial anode. Try bonding the housing to the engine block or frame by attaching a piece of wire between the two.

That said, I would still use either distilled water or premix.

Hey guys, I should have been more clear in my description. The corrosion was on the outside of the gooseneck were the radiator hose makes contact by sliding over. I have seen this kind of corrosion on bolts that pass through a water jacket, or when using a stainless bolt in a dissimilar metal. Resume theories!

[Flashdog]

Bummer! There goes my theory.

[les1234]

Hey guys, I should have been more clear in my description. The corrosion was on the outside of the gooseneck were the radiator hose makes contact by sliding over. I have seen this kind of corrosion on bolts that pass through a water jacket, or when using a stainless bolt in a dissimilar metal. Resume theories!


I have seen this I think on almost every one of the aluminum goosnecks I have had apart. Just seems to be the normal situation. I just clean it up with a wire wheel and put it back together.

If you replace it, watch out for those chrome ones from the auto parts stores, I've had those warp and leak at the gasket surface before.

*note* In my case, the fact that almost every car or truck I ever owned had over 100,000 on it when I got it might have something to do with this!