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Old 04-25-2026, 07:55 AM   #1
kevinshea
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Default reverse flushing my 35.. lower hoses.. suggestions?

Still dealing with the overheating issue but getting closer. Used Thermocure and that looks to have broken up what is considered "gel" fall out from the green antifreeze. (silicate dropout). Also called Green Snot.

It settles in low spots, suggesting a reverse flush.. BUT, the lower hoses are almost impossible to remove and replace.. they are short (like 5") and dual angled.. since the pump and lower outlet centerlines are not aligned.

I will try a variety of methods, but does anyone have a suggestion if I choose to go the lower hose route.. like a VERY flexible short hose.
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Old 04-26-2026, 07:23 AM   #2
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

AI input:

"For a 1935 Ford Flathead V8, a reverse flush is generally not recommended and many experts advise against it due to the risk of dislodging debris into narrow passages or damaging older components. Instead, the consensus among classic Ford owners is to use chemical rust cleaners like Evaporust or Envirorust to dissolve internal rust without aggressive pressure, followed by multiple flushes with white vinegar or distilled water.

Key considerations for your 1935 model include:

Avoid High Pressure: Standard reverse flushing uses city water pressure (40–60 psi), which is far higher than the cooling system's design limits and can blow out freeze plugs or damage the radiator.

Rust Removal: If the engine has significant internal rust, soak the block and heads with a rust dissolver (like Evaporust) for several days before flushing, rather than trying to force it out with high-pressure water.

Coolant Choice: Avoid Evans Waterfree Coolant for this engine; it is expensive, causes leaks in older engines with tiny cracks, and operates at higher temperatures that can be detrimental to a Flathead V8. Use a standard glycol-based antifreeze with a quality anti-corrosion additive.

Procedure: The safest DIY method involves draining the old coolant, filling the system with white vinegar (to dissolve rust/minerals), letting it sit, draining, and then flushing thoroughly with distilled water until clear before refilling with a proper 50/50 antifreeze/water mix."
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Old 04-26-2026, 08:28 AM   #3
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

Thanks Glen.... I have been using Thermocure , a chelate product (same as evaporust) and that is what released the Green Snot. Additional information suggests that to best flush out the gel, do it with boiling water as it makes the crap suspends in the fluid.. then flush quickly.. if you wait, it may settle to the low spots.

Currently all flush is out the petcock.. Monday, I will be removing the upper hoses and flush directly down the heads. see what comes out. Then flush flush flush, and repeat with the Thermocure. .. run the engine... let it cool and flush more.

Trying to rig up an attachment to a hose (like a 1/4 plastic flex line) that will give me access directly to the block.. reverse flush there....

Totally forget.. do I have freeze plugs in my 59AB?

I have also found (suggested here in FordBarn) No Rosion and another alternative for crap removal .. and then after a complete cleaning.. addition of an inhibitor which I am researching, .. I am also in Maine, but store in warm garage.. so considering water only or 50/50 for the coolant.
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Old 04-26-2026, 10:04 AM   #4
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

Quote:
Originally Posted by kevinshea View Post
Thanks Glen.... I have been using Thermocure , a chelate product (same as evaporust) and that is what released the Green Snot. Additional information suggests that to best flush out the gel, do it with boiling water as it makes the crap suspends in the fluid.. then flush quickly.. if you wait, it may settle to the low spots.

Currently all flush is out the petcock.. Monday, I will be removing the upper hoses and flush directly down the heads. see what comes out. Then flush flush flush, and repeat with the Thermocure. .. run the engine... let it cool and flush more.
Sounds good. You may want to remove the upper hoses and thermostats then rotate the hoses on the heads so you can get them close to vertical. Remove the lower hoses. You could run a hose from your hot water heater drain line to the up ended radiator hoses for a flush.

I found on my 59A the even with hot tanking, there was sand and junk just inside of the water pump connection so perhaps pull the pumps too.


Quote:
Originally Posted by kevinshea View Post
Totally forget.. do I have freeze plugs in my 59AB?

I have also found (suggested here in FordBarn) No Rosion and another alternative for crap removal .. and then after a complete cleaning.. addition of an inhibitor which I am researching, .. I am also in Maine, but store in warm garage.. so considering water only or 50/50 for the coolant.
There are no freeze plugs on the 59AB, too bad they could have saved a bunch on blocks. Pic below is for a 39-40 block.

Don't run with just water. Antifreeze has rust inhibitors and also gives you a higher boiling point than H2O


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Last edited by glennpm; 04-26-2026 at 10:10 AM.
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Old 04-26-2026, 01:59 PM   #5
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

I would opt for the 50-50, helps inhibit some rust and no need to drain every fall. there are lower rad hoses made with silicon that are much more flexible.
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Old 04-26-2026, 03:26 PM   #6
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

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At work we had abut 400 vehicles and we kept them around 12 years. I never had much luck reverse flushing radiators. We stocked extra radiators, lots of them, and we just swapped them out and send the used ones out to rebuilt, that's if there wasn't any leakage on the outside of the tubes. If there was the radiator shops would want to re-core them and we just bought entire new radiators instead. You can get the engine warmed up, shut it off and feel around the tubes for spots that are not as hot as others. That tells you those tubes are plugged. But that's new vehicles you want to try and save your original radiator, the aftermarket replacements are nothing like the original Ford's. The tanks don't look the same.

Old Ford radiators were only rated at 4 lbs.; the brass was thick enough but the narrow solder beads on the tanks were weak. That's what old-time radiator guy told me, and I trusted the guy, he was really good. That's why you can't blast pressure in them with your hose you can rupture the tanks seams. You could flip one upside down and let the hose gently run through there, but that gunk is packed pretty tight in the tubes, I'm not sure it would do much good.
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Old 04-26-2026, 04:16 PM   #7
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

Glen and Old Bugger.... I would remove the lower hoses BIG IF I could rest assured that getting them back on won't require a herculean effort. Bugger, do you have a source for the silicon hoses? If I can get the lower hoses on "relatively easy" I would as Glen noted, remove the pumps and make real sure about condition... and doing that, getting a really good access to flush the lower section of most everything.

Actually seeing the Green Snot actually gives me hope that something good is going on... "Better living through chemicals"

Things are taking time since I am working the issue and the car is in someone else's garage. But the good news is that slowness gives me a lot of time to consider everything and do it right.
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Old 04-27-2026, 06:13 AM   #8
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

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Originally Posted by kevinshea View Post
Glen and Old Bugger.... I would remove the lower hoses BIG IF I could rest assured that getting them back on won't require a herculean effort. Bugger, do you have a source for the silicon hoses? If I can get the lower hoses on "relatively easy" I would as Glen noted, remove the pumps and make real sure about condition... and doing that, getting a really good access to flush the lower section of most everything
You probably won't find silicone hoses in an S shape.

Regarding getting the hoses back on, wetting the ID with antifreeze or RuGlyde, sold by NAPA and great for mounting tires too, will help.
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Old 04-27-2026, 12:08 PM   #9
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

UR market outlet is where i saw the offset hose, 1/2 inch offset 6 inch length. i know they are on ebay
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Old 04-27-2026, 12:12 PM   #10
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Default Re: reverse flushing my 35.. lower hoses.. suggestions?

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UR market outlet is where i saw the offset hose, 1/2 inch offset 6 inch length. i know they are on ebay
https://www.fordbarn.com/forum/showthread.php?t=158530
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