Don't use car antifreeze as a coolant

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deverett

deverett
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A sad story. This is a Scott vacuum engine and is stored in a sealed wooden travelling box when not out for running.

Believing that ordinary tap water would cause corrosion of the cast iron cylinder in the bronze cooling hopper, I decided to use car radiator antifreeze as a coolant. After all, most rads are copper and many cylinder blocks are cast iron. Bad idea as you see below.



The fumes from the antifreeze not only corroded the submerged part of the cylinder but went on to give the rest of the bare metal a 'patina' - not one that I wish to see too often. Even the brass parts were attacked.

Note to self: In future use a rust INHIBITOR fluid. I have been told that Fernox is a brand name for such a fluid in the UK, used in central heating systems.

I have stripped down and cleaned up everything except the cylinder. Wondering how to dissolve the rust so that I can knock it out. Thinking about the Alum treatment - but briefly.

Dave
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Blogwitch

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When you mentioned it before Dave, I didn't realise it was that bad.

I was going to use antifreeze in mine because I have used it in other ic engines without any trouble (well the bits I could see), but I think I won't bother now.

Furnox works, I think, by putting a gel like protective layer over the parts it is in contact with.
I think when I get ready for running, I'll just pinch some mix out of my central heating header tank, as that is what I have used in my heating system only recently.


John
 

dedaddy007

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The best thing I have found to remove rust from steel or cast iron is Evapo-Rust. See theruststore.com for more details. You can get it at most automotive supply stores. It is pH neutral and is biodegradeable. No acid or alkalies. It does not touch paint and nonferrous metals. It also helps keep cast iron from rusting. I use it to restore old woodworking and metal working tools.
 

deverett

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Rust removing. I seem to remember in the dim distant past a recipe for rust removal using vinegar and bicarb(?), well something to add to the vinegar which dissolved the rust. It worked, but as soon as the metal was removed from the solution, it started to rust again.

Looking on eBay (UK) I can find Oxalic Acid, but no Evapo-Rust. I wonder if Oxalic Acid has the same effect as the vinegar treatment?

John. You should get enough treatment from your CH system for the Scott, but what about the R & B?! Fernox F1 concentrate is available on eBay, so I might go for that, to hell with the expense.

Dave
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deverett

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Thanks for the link, Gary. Problem for me is the cost of postage to Ireland can be prohibitive. Light weight packs = cheap= better. Think I will try the Fernox first.

Dave
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deverett

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Searching through my stock of old paint, I found some Jenolite rust remover. I painted this on the parts of the cylinder that I could reach, left it for 20 minutes and then scraped as much muck off as I could.

A wooden block on the end of the cylinder and a largish hammer, and a few blows later, out came the cylinder.



Everything has now been cleaned up and after a new coat of paint, I will be ready to start re-assembly. I had to take a 7 thou cut off the exposed part of the cylinder to clean it up.



Looking at the cylinder, reminds me that if a cylinder liner has to be pressed in place, it is better to have the first end of the liner a smaller diameter by a few thou than the rear end. That way, the liner can slide easily in the start of the cylinder and there will not be the struggle of pressing it all the way through.

You can see the ridge on the left hand side in the picture.

Dave
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Blogwitch

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Just a question Dave if you don't mind.

I am undecided whether to paint the bronze water jacket or not. Mainly because of scorching any paint that I put on there.

How did your paint hold up to the gas flame?

If it was OK, which paint did you use?

Thanks


John
 

deverett

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John

Seeing the work you put into your hopper, I would be in no hurry to paint it. It may need polishing from time to time, though!

On my hopper, I tried to equalise the angles of the sides with file and car body filler so I had to paint it. Car body filler hides a multitude of blemishes under a coat of paint.

On all my castings, I start off with a coat of spray etching primer. Have a look at eBay 220668463452 for the brand that I use. From then on, I use rattle can primers in different colours, rubbing down between coats until I can get a reasonable surface. Top coat is Humbrol on this engine, but on the Robinson I am using Japlac, except for the base which is barbecue heat resistant paint.

For the first few runs everything went well and the paint stood up to the warmth of the hopper. Then one time unexpectedly I had the flame far too high and the paint suffered a scorch mark where it received a direct hit. Under normal use, there should be no problem with using a top coat of enamel of your choice. The cylinder head gives a good shield to the nearest paint. Once the engine has been run in, it is surprising how low the flame can go to keep the engine running.

Dave
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Blogwitch

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Thanks for the info Dave.

That water jacket casting was really the only one that I was disappointed with, it had such a lean in all directions, I didn't think filler would have worked, so it got the squaring up treatment instead. Plenty of meat still left on it though.

I have the etch primer and heat resist laquer already, and I too am going to be using Midnight Blue Japlac on the engine itself, a perfect contrast with brass and stainless steel, but to help prevent the problem you have had, I am thinking of swilling the whole inside of the water jacket and cylinder with epoxycote, after everything is assembled of course.

I will be having the same problem on the R&B as well, as Rob Wilson on MM cast me up a wonderful water hopper to my design instead of the original design copper water jacket. So this Scott one is a sort of trial run.

I actually got back into my shop the other day for the first time in many months, but the Scott will be a few months off being restarted, as I still have a few things to do that I promised myself and my late wife I would carry out before doing anything with my engines.

John
 

bezalel2000

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Hi Dave

Those pictures are enough to bring tears to the eyes of any grown modeller.

If you don't mind me asking - do you know what the anti freeze was made from?

was it a glycol - of some sort, typically dyed green or red

Ethylene Glycol or
Propylene Glycol or
something different altogether?

Bez
 

deverett

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Bez

Just looked at the container. It is Ethylene Glycol based and is a muddy green colour. It's about to be given away to a second hand car dealer, 'cos I won't be using it!


Jason

Thanks for the suggestion, but I have just lashed out on a tube of Fernox F1 concentrate.

Dave
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