Stationary Engine List

Keeping Rust at Bay

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I'd like to start this issue with a big thank you to the organizers of the annual gas engine and tractor show in Portland, Ind., who, as usual, did a superb job of ensuring that the whole week went smoothly. And also, thank you to the folks who introduced themselves and told me how much they enjoyed my articles -it's nice to be appreciated!

I had my doubts about producing anything for this issue of GEM since I hadn't prepared an article before I left for the 2003 Portland show and accompanying family holiday. That left me just five days after my return to England to get over jetlag, deal with three weeks of paper in the office and get my life back to normal. I did manage to read the ATIS Stationary Engine Mailing List mail, which came within the first day or two upon my return. Today, I had another look at some of the conversations beyond 'didn't we have a great time at Portland?' and found a discussion that may interest water-cooled engine owners.

Since many of the European List contributors were traveling, this was largely an American-Australian topic, proving perhaps that some things are the same the world over. This started with an Australian's question:

I have several large engines that I run every so often. What can I put in the water tank to stop or slow down rust? I don't want to refill the tanks all the time.

Easy to do. Toss some plain tea bags in next time you run the engine. This will help seal the water hopper because of the tannin in the tea. Run it for a day, then take the tea bags out and drain the water. Now you can fill it back up without worry. Just don't forget to drain the water in the fall, or you'll be welding in the spring.

I use sump oil in my engines, especially my hopper-cooled ones. With the hopper-cooled engines, I fill them to the top, run the engine for a while so the oil heats up and soaks into the iron, then drain it out.

After a day's rallying with my tank-cooled engines, I top the tanks with about 3 inches of oil, and when the water drains it takes the oil with it, coating everything. It's a little messy, but cheap, and you only have to do it once.

I like to run an antifreeze mix in my water hoppers. This is how I treated an Associated engine last summer:

1. I drained all the water out, removing as much gunk as I could.

2. I sandblasted the inside of the hopper.

3. I filled the hopper with water and tossed in a big tea bag.

4. I filled the gas tank and ran the engine until it stopped. I ran it fast so it would get hot.

5. I removed the tea bag and drained the hopper.

6. I put a 40 percent antifreeze mix in the hopper.

How to 'cure' the water hoppers was a hot topic a while back, and that's where I got the idea to use tea. Someone suggested using oak leaves since they also have a lot of tannin in them.

I just checked the Associated hopper and there's still no visible rust. I like this method because it smells nice when I'm curing it.

I keep water in my hoppers all the time. They're stored in a garage, so I never have to drain them. I use a mixture of water and oil. It inhibits rust, and when you drain them, it leaves a coat of oil on the inside. It doesn't harm the cooling capabilities, either.

I usually fill the hoppers about 3/4 full with water, and I squirt a little oil into the water. When the water gets hot or boils, the oil mixes. As the water level decreases from evaporation, the oil attaches to the sides of the hopper. I feel that water alone in the hopper allows rust to form even below the water level. I use the same oil in the water that I use in the drippers - 20W50 - because that's what I use in my truck. The only problem is that it leaves an oily scum on my ravioli cans when cooking!

Obviously the tea and oil suggestions weren't exactly what was required, so the Australian clarified his question.

I have a half dozen large tank-cooled engines with some holding up to 40 gallons of water. I have noticed a small amount of rust forming in the water tanks.

My son and I run the engines every few weeks, so it takes a lot of time and water to drain and refill each time. Is there some compound or chemical that would allow me to leave them full? The hopper-cooled engines are no problem, since we refill them as needed.

Try putting soluble oil in the tanks. It makes a bit of a stain, but it won't rust them. It may look ugly, but it seems to keep the water oily enough. Make sure you don't pay too much for it though, some places have quoted me ridiculous prices.

A big reason I use TSP-PF (sodium metasilicate) is that it's cheap. Anything made for scrubbing bricks and concrete pretty much has to be cheap. It's available at paint and hardware stores.

I put TSP-PF in the cooling tank of my Lister diesel clone. It prevents rust and also precipitates hard water minerals before they can form hard scale on the hot surfaces of the jacket. The precipitate does settle as a fine white mud in the bottom of the tank, but rinses out easily with a hose. Sodium silicate is a common additive to commercial antifreeze and coolant products for the same reasons. Real TSP (trisodium phosphate) will work much the same. It's banned here, but is also found in commercial coolant products.

If I don't use the silicate (I forgot it when I went to Portland this time), the cooling water drains out quite rusty even after only a day or two. If I add several ounces to the tank (a small paper cup full in my 25-30 gallon tank), it drains out rust-free after months. Of course, it takes a few drain/refill cycles to get out existing loose rust.

So there you have a variety of solutions for the prevention of rust in hoppers and cooling tanks. But as usual with the mailing list, one subject leads to another, and this one was no exception.

Did you know that some of the N-type hopper-cooled Ronaldson Tippets ran oil in their hoppers?

Oil in a cooling hopper won't work well for cooling. It doesn't boil until it's extremely hot. Evaporation is minimal. It only radiates heat from the limited surface area of the hopper and from the top of the liquid oil with convection air carrying away the heat. The thermal gradient must be very large to carry off the heat generated by a running engine that way. A good oil coat in the top of a hopper full of water won't hurt anything, nor will oil emulsified with the water. The water will still boil and carry away large amounts of heat at a constant temperature.

Here's my take on this question. Heat can travel by three means. Conduction: Heat touches something and transmits its vibration. Radiation: Heat travels by light waves, mainly infra-red unless you run your engine really hard and it's hot enough to emit visible light. Convection: The heated substance is a liquid or gas and gravity moves the heated and expanded gas away from the heat source.

A dry hopper won't conduct much since the cylinder barely touches it. Convection doesn't work well in a dry hopper since the air doesn't circulate well. But, if you fill the hopper with oil or water, convection will move heat from the cylinder to the hopper. The hopper has much more surface area to both radiate and convect heat. Oil can do this nicely.

If the engine is working hard, and if the rate of heat flow from the outside hopper surface is less than the rate of flow from the cylinder to the liquid - be it water or oil - the liquid's heat will increase and the boiling point may be reached. When that happens, the evaporating (boiling) liquid will carry away heat as it evaporates, and you'll see a need to add more liquid from time to time. Depending on the liquid, this may occur at varying temperatures.

When we used alcohol/water mix for antifreeze in our automobiles, we lost the alcohol pretty quickly if we overheated the engine. So, the liquid in the hopper helps cooling by convection. If you touch it, and burn your hand, you have experienced conduction.

But is convection enough for a working engine? A running Fairbanks-Morse 1-1/2 HP will boil out water. Put a load on it, and I suspect oil would not be enough. I could see convection cooling working - but enough?

I think that the oil would be enough for a working engine. Among the advantages of oil or water in the hopper is that it helps keep the heat around the cylinder even. It prevents a hot spot or, at least, helps lessen it.

The oil cooking in the hopper must really stink if the thing is working hard, and I suppose it could cook down after a while, couldn't it? If you have oil in the hopper and the engine is running under a load, keep an eye on the piston. If the cylinder and piston get so hot that the lubricating oil on the piston starts to break down, you are in big trouble. We want to run the engine as hot as we can but still have effective lubrication.

Luckily, those wrestling with this concept were put out of their misery by further explanation behind the oil in the engine's hopper.

These engines were used at brick manufacturers. The oil in the hoppers was only there to heat up the engine and was then transferred to the kilns to fire the bricks.

Temperatures are dropping, and winter isn't far away, so don't put off draining the water out of your engines and doing whatever you need to prepare them for the cold weather. Do it now and save yourself a lot of problems in the spring.

Now I can go back to sorting out photographs and Web pages post-Portland. We spend six months of the year preparing for Portland, an intense week there and six months savoring the memories.

Engine enthusiast Helen French lives in Leicester, England. Contact her via e-mail at: You can join the Stationary Engine List on the Internet at: