Coolant in thermosiphon systems

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70shovelhead
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Coolant in thermosiphon systems

Post by 70shovelhead » Sat Jun 22, 2019 7:06 pm

Im going to ask a question here that comes up occasionally at antique farm engine shows I attend. I've always been told, and have done this with my thermosiphen tractors, that you are not to run anything but straight water in thermosiphen cooling systems. Reason being that "coolent" raises the temp 10 to 12 degrees before the coolent will circulate. Water pump systems will work fine with coolant but thermosyphon systems wont circulate until the temp reaches 220+. Not to open a can of worms but I have had non waterpump tractors (fordsons, farmall cubs and my 10-20 Titan and a couple of Ts) that I have only ever run straight water in. I do live in the south so freezing is not an issue. We do drain radiators in the event of a freeze. With all the discussion concerning our Ts running hot especially non water pump cars I never hear this brought up. I think most that run anti freeze/coolant in their thremo systems do it in an attempt to prevent rust when actually most of todays coolants are hard on old radiators and may be doing more harm than good. Just looking to see what the thoughts are on this.
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Les Schubert
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Re: Coolant in thermosiphon systems

Post by Les Schubert » Sat Jun 22, 2019 7:19 pm

I’ve run Ethylene Glycol (about 35-40%) in my 27T for 44 years. Works fine!! No corrosion issues.


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70shovelhead
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Re: Coolant in thremosiphon systems

Post by 70shovelhead » Sat Jun 22, 2019 7:25 pm

Guess I was looking more for overheating issues.
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Dallas Landers
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Re: Coolant in thremosiphon systems

Post by Dallas Landers » Sat Jun 22, 2019 7:28 pm

I run 50-50 with a recore radiator. No overheating, not even close. It was 80 yesterday and I was moving things around in buildings. It ran at a brisk idle for half an hour and didnt even boil on shut down.


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Re: Coolant in thremosiphon systems

Post by Erik Johnson » Sat Jun 22, 2019 7:31 pm

I don't think it matters.

I don't believe that the coolant has to be near the boiling point to circulate via thermo-syphon regardless if the boiling point is 212 or 223. There only needs to be a difference in temperature between the coolant in the block and the coolant in the radiator in order physics to do its thing and circulation to occur.

Just thinking out loud. Feel free to correct me if I am wrong.

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Re: Coolant in thremosiphon systems

Post by CudaMan » Sat Jun 22, 2019 7:48 pm

The thermosiphon convective action will begin once the coolant gets warm enough to create a density difference between the warm and cold coolant. The coolant doesn't have to get close to boiling for the convection to start.

Like the others, I have run a mix of coolant and water in my T for years with no hint of overheating problems. :)
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Re: Coolant in thremosiphon systems

Post by Scott_Conger » Sun Jun 23, 2019 1:14 am

Eric, Mark

both have it right

this is not something to worry about or overthink

Efficiency is another thing...water will marginally cool better on a terribly hot day with a hard-working engine. Polished brass is another thing...coolant is tough on that pretty brass, but over the long term, water is tough on cast iron. You pays yer nickle and you takes yer chances.
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Re: Coolant in thremosiphon systems

Post by Humblej » Sun Jun 23, 2019 7:00 am

50/50 antifreeze.


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Re: Coolant in thremosiphon systems

Post by Gonenorth » Sun Jun 23, 2019 8:14 am

I run mine closer to 40/60% antifreeze adjusted to -47. Yep! It can get darn cold up here in the tundra. And "no", I don't drive it in the winter. It lives in an unheated garage from mid-October until mid-April. I have a good flat tube radiator and the car never overheats even when we get into the occasional mid-90's with humidity to match.

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Re: Coolant in thremosiphon systems

Post by Steve Jelf » Sun Jun 23, 2019 11:36 am

If a Model T cooling system runs too hot with antifreeze it it, the problem isn't the antifreeze. It's the dirty/clogged system, or the radiator is kaput. Maybe pure water cools better than antifreeze, but it doesn't matter. The Model T cooling system in good condition does its job either way. Preventing rust is better than not preventing rust.
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Re: Coolant in thremosiphon systems

Post by John Codman » Sun Jun 23, 2019 12:39 pm

My '27 simply will not overheat with a 50/50 ethylene glycol/water mix. If you have a clean cooling system with a good radiator the system will work fine.


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Re: Coolant in thremosiphon systems

Post by Aarongriffey » Sun Jun 23, 2019 1:15 pm

The idea that so many have that the water or coolant has to be boiling to make it thermosyphen, or circulate, is one reason I don’t spend a lot of time reading forums.
If the water in the engine is 61 degrees and the water in the radiator is 59 it will thermosyphen.
That is unless it is on Friday the 13th and you left a car battery sitting on concrete.
People have been running cars, truck and tractors in sub zero weather for many years and leaving the same anti freeze solution in all summer for many years without overheating.
It is true that straight water will carry the heat off better than an anti freeze mixture but it is also true that you’ll get better gas mileage if you remove your hubcaps and spare tire. And the jack n tools under the seat.

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Re: Coolant in thremosiphon systems

Post by BuddyTheRoadster » Sun Jun 23, 2019 6:14 pm

On my car, Dad ran straight water with an ounce or two of soluble oil to inhibit rust. There haven't been any problems to speak of since 1995.


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Re: Coolant in thremosiphon systems

Post by samuel pine » Mon Jun 24, 2019 8:20 am

50/50 antifreeze runs 195 on the hottest days original radiator no pump no steam either.....


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Re: Coolant in thremosiphon systems

Post by John kuehn » Mon Jun 24, 2019 8:34 am

Think I will keep using 50/50 mix and forget about it.


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Re: Coolant in thremosiphon systems

Post by Scottio » Mon Jun 24, 2019 11:00 am

I use a little coolant and distilled water mainly to keep rust from forming. It works great here in the desert where It gets over 110 in the summer and into the single digits in the winter. It doesn’t seem to effect the cooling ability one way of the other.


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Re: Coolant in thremosiphon systems

Post by Tiger Tim » Mon Jun 24, 2019 5:54 pm

I’ve been using pond water this summer but in the fall I’ll have to remember to switch it to creek water - the creek doesn’t freeze like the pond does.


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Re: Coolant in thremosiphon systems

Post by Gonenorth » Mon Jun 24, 2019 9:23 pm

Tim, You're right on Lake Superior. Just use some of that water. That lake hardly ever freezes.

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Re: Coolant in thremosiphon systems

Post by RustyFords » Tue Jun 25, 2019 6:39 am

Gonenorth wrote:
Mon Jun 24, 2019 9:23 pm
Tim, You're right on Lake Superior. Just use some of that water. That lake hardly ever freezes.
:D

Great ideas Tim and Kevin!

I'm going to take it a step further. Living so close to the Gulf of Mexico, I've noticed that it never, ever freezes. I'll think I'll run some of that water in my T. ;)
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Re: Coolant in thremosiphon systems

Post by Hal » Tue Jun 25, 2019 7:36 am

I use antifreeze and have no cooling problems with either of our T's.

It's funny to see people that actually carefully mix particular ratios of antifreeze to water. On occasion, I have pre mixed coolant, but usually for my hit and miss engines or back when I had bad radiators on the T's and needed to top them off every time I turned around. I didn't want to get the mixture so diluted it would no longer protect in the winter, so I mixed some in a jug for that. Other than that, when I change antifreeze, I put a jug full in the empty system and fill the rest with water. I have no idea what that ratio is, but it is certainly enough to keep from freezing in my area. We get freezes, but my shop is insulated. I don't know if it ever gets below freezing in there or not, but I wouldn't want to find out the hard way, so I do use antifreeze. I could probably get by with a lot less if I were to mix it to some degree (See what I did there?) of protection, but I just never bothered. Folks in cold climates? I do understand needing to be more careful.


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70shovelhead
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Re: Coolant in thremosiphon systems

Post by 70shovelhead » Tue Jun 25, 2019 9:47 am

Alot of good replies. Thanks for all.
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Re: Coolant in thremosiphon systems

Post by Norman Kling » Tue Jun 25, 2019 11:26 am

I live at 2,350' elevation in San Diego county. We rarely get cold enough to freeze a radiator, maybe once during a typical winter. Our water is very hard and creates residue. Also possibility of rust in steel parts. I use Prestone, the green stuff with one gallon anti freeze and top off with distilled water. When I need to add coolant, I just use the distilled water. This combination will keep away rust and sediment and also prevent freezing. Lowest temperature I have had here was 18F and have lived here 45 years. Usually just hovers around 32degrees until sunup.

In the summer we can get up to the low 100's here and it is all uphill for about 10 miles. The motometer stays around "Normal Summer Temperature" going up the hill. When I turn off the engine after I get home, it gurgles a couple times. It doesn't usually require adding any coolant. I have a flat tube replacement radiator.
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Re: Coolant in thermosiphon systems

Post by Moxie26 » Tue Jun 25, 2019 10:23 pm

Consider Evans non-aqueous coolant.................. works well with thermo-syphon systems. Ive been using since 1998.

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