Re: Radiator flush fluids

Posted by Fish'n Jim On 2024/4/9 21:44:41

Prestone "flush" is plain old TSPP = tetra sodium pyrophosphate. Available at most hardware/bigbox stores. An alkaline cleaner that's good for steel, etc. Aways want to be alkaline with iron, and not too strong. More iron can dissolve at high pH ~13, than above 7. (Iron only, not good for aluminum!) There's a curve for that.
I'd just flush it not running with the hose in the cap and drain open until the water comes clear, then clean it with flush and running to heat it up. Drain, flush again, and drain it dry. Can blow some air through it to get the last and then add the 50/50 antifreeze. I use DI/distilled water to mix as the premix is more expensive, and tap water can put hardness, pH, which can lead to deposits in the system/breakdown of the EG. I did that on the '49 and then found the hose neck was rotted and had to be repaired. I tested the thermostat to make sure it was correct and opening. One pin hole and they won't work. Capsule has to be intact. It would idle for an hour with no change in T. It had sat in a field for at least 5 years and not ran for a long before.
Old radiators have a heavy solder content, so PbO layer shouldn't be disturbed with what you clean it with.
Back in that day, '28, alcohol was the antifreeze of choice, but it boiled out overtime and had to be replaced frequently.
The modern anticorrosion inhibitors in the EG antifreezes should be sufficient to protect what you have. Change at about 5 years.
It's hard to say what or if the "verge of overheat" is caused or from as designed. These radiators are not pressurized, so boiling will be about 212 or so at sea level. Since you're operating in high elevation,(Denver) that could be your problem. BP goes down with altitude. It's really not a problem until it comes gushing out and loss of fluid. If it boils, then you get steam pockets, and steam is not a good heat transfer medium and superheats, pressure rises in block, and then it expands and moves everything out. Not good for the lubricated side. Pressurization inhibits that nucleate boiling issue. {They weren't too heat transfer swavvy in '28.}
The air flow is more critical to remove the heat than the cooling side film, unless flow is retarded due to sludge, plugged passages, or weak H2O pump/if not a thermosyphon system. Check your belt and fan and any missing air dams. Impellor may have rusted over time. Something to check as is the thermostat for operation or blockage, also.
Fine surface roughness has little or no impact to HT area as it's within the laminar zone. The fins are what help. Plus not much air moving inside the engine compartment.
My personal rule is not to experiment/play around with hard to replace antiques and modern 'solutions' without exhaustive testing and verification. There all kinds of hearsay suggestions out there without proof, but sworn by. Not saying they aren't good, but without documented proof - won't stand up in court! One reason I usually don't recommend products and certainly qualified to do so.
Definitely don't run just RO/DI water without any inhibitor in the system, even for short runs. Water itself is corrosive. Old cast, gaskets, etc are of unknown condition, so you don't want to open up any faults that were sealed by corrosion products... When one operates a 'million ohm' water system, they use non-metallic pipes, etc. so it doesn't pick up any metal ions.