is it ok to run diluted antifreeze?
 

Flatties naturally run hotter than the average engine. On my modern every day driver I've been using the 50/50 with no problems except a water pump went south. I've been reading up on the debates of the subject and no one totally agrees on it.

Re: is it ok to run diluted antifreeze?
 

Flatty's run hotter than the average engine you say? News to me.

There is no debate among folks that have a basic understanding of thermodynamics.
Pure water will dissipate heat better than any diluted mixture.
Is your vehicle at risk of freezing in your area? If so, then you (obviously) must add anti-freeze to the cooling system.
If there's no risk of freezing, water is best with some type of water pump lubricant. That's available at NAPA, etc.

Re: is it ok to run diluted antifreeze?
 

50/50 mix is best
I personally would never run just water ,
With antifreeze it helps keep the rust from forming


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Re: is it ok to run diluted antifreeze?
 

50/50 mix is best
I personally would never run just water ,
With antifreeze it helps keep the rust from forming


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Living where you do - Michigan, I too would not run straight water.

As far as anti-freeze helping keep rust from forming, that's what water pump lubricant does.

Re: is it ok to run diluted antifreeze?
 

If flatheads ran hot you wouldn't need thermostats, LOL. The thermostats do bring the engine up to temperature quicker, but they are also required to maintain a minimum operating temp. It is not uncommon for a flathead to run in the 150 to 160 degree range without thermostats. If your engine is running hot something is not correct, radiator issue, water pump issues, crud buildup in the block, improper fan, sheet metal missing, something ain't right.

Re: is it ok to run diluted antifreeze?
 

Even though I live in Wisconsin, I run straight water. My car is in my heated shop during the winter. I use a boiler chemical to fight corrosion. My pumps have sealed bearings so do not require a lubricant.

Re: is it ok to run diluted antifreeze?
 

when we bought our '41 ford we changed it to a SBF. I sold the F/H to a guy that ran only water in his F/H/. His son went snowmobiling and forgot to close the garage door and he ended up with a cracked block. I'd never run straight water even in the summer.

Re: is it ok to run diluted antifreeze?
 

Why not use it as recommended? It is not expensive!

Re: is it ok to run diluted antifreeze?
 

When I was living in the Arizona desert, flatheads ran hot. I had a '49 Pontiac with a flathead straight 8 and it ran 190 to 200. I never ran straight water in anything and back then 50/50 hadn't been developed yet (I moved away from there 30 years ago) In my post I was more concerned for the engine and cooling system and if 50/50 would cause rust to build up quicker.

Re: is it ok to run diluted antifreeze?
 

I run antifreeze/summer coolant and use it about 3:1 so it's 25/75 coolant/water. Tend to have mild winters here.

Re: is it ok to run diluted antifreeze?
 

I run 50/50 all the time because of where I live. I believe permanent anti-freeze has anti-rust chemicals in it, but I still add some rust inhibitor and change the anti every two - three years. I mix the 50/50 myself and always check the freeze point.....Mark

Re: is it ok to run diluted antifreeze?
 

Antifreeze is made to be diluted. Concentrate is not intended to be run 100%.

Of course, you could run premix at twice the price.

It works best as instructed by the manufacturer. There shouldn't be anything to debate about.

Re: is it ok to run diluted antifreeze?
 

Why not use it?
Anti-freeze does not dissipate heat as well as pure water.

Re: is it ok to run diluted antifreeze?
 

50/50 mix here too, using distilled water. I run that in all our antique Fords and the coolant is always fresh and clean looking. Not gunky and rust colored like so many I've seen w/o antifreeze and or rust inhibitor:eek:

Clunked up dirty coolant killed an awful lot of heater cores from cars I saw being worked on at the local Ford garage in the early- mid 70's. And on Mustangs they were a fit to change, it was not an easy job. Guys used to just bypass the heater core and not run the cars in the winter.

Galaxies were a snap to change, they came out in the engine compartment after removing a plate and the heater hoses:)

Re: is it ok to run diluted antifreeze?
 

I run antifreeze with 180 stats in an 8BA...the hottest it ever ran was 190 on a very hot day during stop & go driving.

Re: is it ok to run diluted antifreeze?
 

I always run a 60 / 40 mix.
Vic

Re: is it ok to run diluted antifreeze?
 

If your Flatty is running hot you have an issue! How do you know it’s running hot? don’t trust those gauges! use a laser temp gun to confirm actual temp.

Re: is it ok to run diluted antifreeze?
 

I run a summer mix 50/50 of glycol antifreeze to help keep the system clean and rust free, along with a 12-14 degree rise in the coolant boiling point, something that has not been addressed yet.

Re: is it ok to run diluted antifreeze?
 

Good point. I always run 50/50 in everything, because at my altitude water boils at 202°.

Pic is of my head's cooling passage after 5 yrs from a rebuild, during a thermostat change. Can't beat that!

Re: is it ok to run diluted antifreeze?
 

I have seen charts showing the change in boiling point and freeze protection of different ratios of coolant/water. Sorry I don't have a link.

More water than coolant is "supposed" to dissipate the heat better, but, you better make sure of the boiling point and freeze protection for your area. And what pressure cap you have.

I experimented with 60/40 and 70/30 on a blown small block in my "non Ford" tow vehicle in hot summer temps. The 70/30 did seem to limit the temp climb towing my boat up long steep grades in 100 degree plus temps. Not trying to start any "heated discussions". Just my one test on my specific application. I wanted to see if it was true.

I run 50/50 in my Flathead in this heat without issue.

Ross, that's squeaky clean.