MTFCA Forum

I need to flush the radiator on our 21 touring. I was planning on using vinegar, and had a couple of questions:

1) Some recommendations said 1 gal vinegar and 1 gal water. Another 2 gal of vinegar. Any recommendations one way or another, based on your own experience?

2) Is it better to just let the vinegar or vinegar mixture marinate in the radiator, or is it a good idea to run the engine for a bit before letting it sit over night?

Any other helpful suggestions would be appreciated. Since the coolant will be drained for doing this, I plan on removing the side mounted water pump and put it back to original configuration.

thanks,

Neal

I put 2 gallons then water to top off, run in multiple cycles for a few days. Then drain cold with the lower radiator hose removed. Collect the old vinegar for a good weed killer. Will do you proud!

Hank

Retorque the head cold!

As Henry stated, leave it in the cooling system for a few days. A few weeks is even better. It is to dissolve build up of minerals and rust, takes time to do that.

Since vinegar is a mild acid, would it be advisable to follow the flush with several tablespoons of baking soda through the cooling system to neutralize any remaining vinegar residue so new rust will not form over time? This to be followed by fresh water or 50/50 coolant. Jim Patrick

No as baking soda is a salt, just rinse with water really well and watch all the crap come out!

Be careful with the flush.
I finally got all the crud out of the block and radiator.
Now the petcock leaks and I have to change the casting plugs.

jiminbartow wrote: ↑

Mon Jun 29, 2020 10:04 am

. . . neutralize any remaining vinegar residue so new rust will not form over time?

Really no way to entirely eliminate corrosion. Antifreeze mixes retard corrosion. Running straight water, many add a pint of soluble oil. YMMV

I prefer to remove the radiator and lay it on its front after sealing the filler with a plastic bag and a strong rubber band. Pour enough vinegar in to fill the core and leave for a day. Re collect the vinegar and flush the radiator with the garden hose and reinstall!!

I strongly prefer to keep the vinegar away from the block and core plugs and gaskets!!

I'm working on a fella's Model A and am going to add Thermocure, an Evaporust product. After draining the system, one adds the quart of treatment to
the radiator with the appropriate amount of water (preferably distilled), run the car normally for several hundred miles, drain system, flush multiple times until it runs clear then add your preferred anti-freeze & water.

I second Les' post. This is how I treat radiators and when possible, keep pretty much everything out of the block other than cooland and distilled water. It's remarkably effective, and you don't need 30% vinager from hardware stores, in fact that concentration brings its own set of cautions and headaches. Off the shelf in grocery store is just fine.

As an aside, more concentrated acid does not necessarily "disolve things" faster. Sometimes it is a weaker solution that is more agressive...just depends on what the acid is being used for.

I like Scott and Les’s method, but don’t like having to remove the radiator as with all the parts you have to remove to get the radiator off, it is one of the more difficult jobs I intensely dislike. If you are lazy like me, in your old age, you can do their procedure with the radiator installed, by removing the inlet hose and seal the radiator outlet with a piece of plastic and a hose clamp. When the vinegar has been in long enough, remove the hose clamp and plastic and flush the radiator with clean water. Jim Patrick

Found this article about radiator rust https://dsportmag.com/the-tech/thermocu ... t-remover/
this is just a portion "... Instead of getting into the chemistry of the galvanic properties of different metals, the important thing to remember is copper accelerates the formation of rust on iron.
Cast-Iron, Copper and Aluminum
While domestic vehicles were produced with cast iron engine blocks, cast-iron cylinder heads and copper radiators well into the 1990s, most imports since the early 1960s have featured aluminum-alloy cylinder heads. While a cast-iron block/head and copper radiator system is likely to have the highest amounts of rust formation in the cooling system, a cast-iron block/aluminum cylinder head teamed with a copper radiator is also a great candidate for excessive rust formation. Besides excessive rust formation, the aluminum cylinder head(s) add(s) another complication. Depending on the pH level of the coolant and the type of coolant used, it’s very likely that the aluminum cylinder head becomes the sacrificial material in the cooling system. This often leads to erosion of the coolant passages in the cylinder head or intake manifold. If you are unlucky enough to have a tri-metal cooling system (cast-iron, aluminum, copper), you’ll need to plan on regular coolant changes every 2 years or 24,000 miles. ..."

I am with Steve on this. I tried vinegar and several other flushes with unsatisfactory results. I ended up using Thermocure and it did the trick. I have since used it on 2 others with very good results. You can even drain it and reuse it multiple times, if needed.

If you still have the container, what are the active ingredients of ”Thermocure” that makes it more effective than Vinegar? Would a 50/50 mixture of muriatic acid and water make a good radiator flush? Jim Patrick

Evaporust and associated products convert solid Iron oxides to water soluble Iron Chelate in a near-neutral pH solution, but do not react with the base metal like acids do. I have no association with Evaporust or Thermocure so this is NOT an endorsement on my part. From the posted link:
"One of the unique properties of THERMOCURE is that its pH level is essentially balanced to a neutral level. Its pH will measure somewhere between 6.0 and 7.0. Since its pH is essentially neutral, there isn’t a risk of trace amounts (from an incomplete flush of the cleaner) impacting the pH levels of the coolant. Like EVAPO-RUST, the method by which THERMOCURE removes rust from the cooling system is called chelation. When THERMOCURE comes in contact with rust, its chemistry attracts the rust away from the metal and to itself. "

I’ve ordered a new radiator and wanting to prepare the water channels/jackets beforehand to help create as optimal a system for the new part. I’m guessing it’s common but I can see rust lining all the inlet and outlet interior.

I emailed the maker of thermocure to ask them some questions about their product’s use in a T’s block; especially because I don’t have a radiator to run the engine with the thermocure in the coolant mixture... if I read the instructions right. I’d have to use it as a soak.

Anyone have experience using thermocure? Do you think it would be effective as a soak? I’ve read previous threads suggesting vinegar, phosphoric acid, molasses, etc. I haven’t figured out what trigger you pull yet on treating the water channels prior to installing a new radiator.

Darin

I like it when original posters provide an update to their original question, so here's mine. I used a gallon vinegar mixed with water and let it soak over night. I then poured enough water through the system until it came out pretty clear. There didn't seem to be that much crud, thankfully. Yesterday I got the new inlet port, gasket, correct length coolant tube and hoses that allowed me to finish the job.

After filling with coolant, I took it for a spin when it was 90 degrees, which included a couple a couple of slowdown or stops at intersections. I had run it earlier to check for leaks, so the coolant was initially above ambient, but below the bottom of the thermometer gauge. I did notice that the temperature registered earlier on the gauge than when driving under similar conditions with the Berg water pump installed. That makes sense, given that the water pump starts circulating the coolant from the moment it starts, whereas I believe that the thermo siphon system circulates the water slower initially. The coolant temp did not get up summer average while driving, and it was steady or would decline during the longer straightaways. I don't think the temperatures are any higher than when I drove the car with the pump; the coolant temp just gets up and stabilizes quicker without it.

Working on a T is sort of like working on an old house. You never know what you will find. My "surprise" on this job was that someone had removed the petcock on the bottom of the radiator and replaced it with a short 5/16 or 3/8 fine thread bolt... It couldn't have been the original restorer, as he seemed to do a proper job everywhere else and doubt that he would have done something so stupid. I chased the threads with a 1/8 pipe tap and installed a brass pipe plug, but it is still dripping a bit...

Neal

You might need to tap out to 1/4" pipe - they make petcocks in 1/4" p.

Today was the 2nd anniversary of driving this car first time, as well as the first time driving a Model T at all. That seemed like a good reason to take the car out. I also wanted to see how the cooling compared to when I would drive the car with the pump installed in similar conditions and temperature. The max coolant temperature did settle in lower than when I drove it yesterday when it was 90, which makes sense. Overall it doesn't seem to get any warmer than it did with the pump installed.

One thing that I did notice was that the coolant temp seemed to come down quicker after driving than it did when the pump was installed. Probably because the pump impeller would block the flow some while it still thermo siphoned when cooling down.

I don't know of a cure-all, but there are several different substances that could need to be flushed from the system. Ordinary dirt is one of them. If previous owners put water in from a ditch, then it makes sense it may still be in the system. Soaking the system with detergent and flushing with high volumes of water may be the best solution. Calcium scale is another. This comes from using hard water, and vinegar may work well for this. Rust generally comes in two forms, red rust and black rust. Red rust can form if the system is open to air and moisture for long periods, but generally black rust is more likely to form in low-oxygen conditions, forming black grit. Evaporust, vinegar or similar products may help with this. I don't know the chemistry of commercial rad-flush products, but they may well take care of several of those factors.

My 2 cents on the use of Thermocure. I used it on my speedster last winter per the instructions. Worked great in cleaning out the block. What came out was quite interesting. However, I have a Livingston, honeycomb radiator, and though the Thermocure did its job in busting up the rust into very fine particles, they became lodged in the very thin water passages of the radiator. I needed to remove the radiator and back flush for a few hours. It got some of the build up out but not completely. Now I know most T radiators are of the round or flat tube type, so they may not plug up, I would caution using Thremocure with a honeycomb type radiator.

When I first took the head off my 23 runabout the water jackets were completely full of flakey rust. I honestly don't know how the engine even ran without severely overheating after a couple of minutes. I removed as much of the rust as I could with a vacuum then put everything back together and filled the radiator with a jug of thermo cure and water then ran the engine several times. When I removed the old radiator to install my new one , I looked into the head and it was completely spotless. I'm pleasantly surprised at how well it worked.

Stephen

I flushed my cooling system with RUST 911. Drain and fill with RUST 911. I actually drove the car with the mix and it remained cool. Let set 24 hours. Drained and water was BLACK. I flushed with clear water and refilled with RUST 911. After sitting for another 24 hours this time the drained mixture was light grey. Flush and refill again. After 24 hours when drained the mixture was clear. After removing the hoses and inspecting with a flashlight not a flake of rust could be found anywhere. All radiator tubes were clear. The rust simply dissolved and was gone. When I refilled the system I added a bottle of rust inhibitor.

Dishwasher soap makes no bubbles.

I have always wanted to try that in the radiator with plain water for cleaning.

On one car I tried everything, Dawn dish soap, Royal Purple, Simple Green, Mac's radiator flush, vinegar multiple times. That is when I discovered Thermocure and tried it. It did the job! I have since used it on 3 other cars.

The advantage of vinegar, beyond being cheap, is that acetic acid cleanses corrosion, but does not touch uncorroded metal. I use it for cleaning anything rusty, such as old tools, nuts, bolts, etc. I think that if you put it in the car and run the car, and you then get leaks at freeze plugs and other such places, then those places were corroded and needed to be fixed, anyway. OK, so maybe you don't want to get that far into car repairs, but perhaps it is better, and less embarrassing, to find those lurking problems now rather than while driving down the road on an expensive tour.

I think I'd be less concerned with getting the cooling system spotlessly clean, than with restoring its cooling capacity.