Technical Define "Overheating"

In the distant past, the only reason that 160 degree thermostats were available was that they were for use with the old alcohol anti-freeze. Alcohol boils at about 170, and it would evaporate and be lost, leaving plain water behind. 180 degree stats were standard for plain water or glycol antifreeze. With a 7 pound pressure cap, a 190 is OK.

True overheating occurs when the radiator can no longer dissipate the amount of heat that the coolant absorbs from the engine. The coolant temp then rises until it boils and lifts the pressure cap.

One way to see the efficiency of a cooling system is to use a second temperature gauge to read the coolant temp at the lower hose connection. The difference in temperature between them is an indication of how well the radiator is doing its job.

 

We were on the power tour and got caught behind a wreck on the freeway. My buddies 350 chevy set idleing for 1/2 an hour with the gauge on 250-260. It never boiled over and got him home, but it was running like crap. When he tore it down the rings had lost tension. So I agree with beaner, its overheated when the engine is being damaged.

 

Evans coolant? It would have boiled over with glycol.

That's the down side of Evans. It allows destructive overheating without boiling.

 

In regards to flathead block cracking, is it from excess heat or from pouring cold water into the hot engine?

 

Right outta highschool I had a 86 Mazda b-2000 lowrider...........anyway, blew a hole in the side of the 4banger and installed a 302 ford v8 with a c4 trans....worst install ever but the truck was bad ass and always drew a crowd...might of been laughing but I thought I was the baddest dude ever.

Anyway, the thing would overheat to the point of running crappy and boiling over at least once.....EVERY time I drove it. I took me over a year of daily driving to finally fit a radiator and fan that would keep it in check. Without exaggerating I did that to it probably 200 times not knowing better and somehow I never had a single heat related problem. Went through a ton of coolant and water though....the engine was used when I got it out of a 68 cougar if I was told the truth...dont understand how I did that but a new car can overheat once and be toast....

BTW didnt have any gauges at all, the factory mazda stuff I could never get to work, I had no idea what I was doing....the way I gauged the temp was how how the heater air was, I had it on all the time even in the summer..always had at least one other buddy with me and we smiled the whole time while we sweated our balls off...now I cant drive unless I have ac....ha...

My girlfriend at the time, who is now my wife, rode in it like a champ, never bitched at all....

 

Exactly right, heat destroys. To increase cooling increase airflow.

 

If you don't know, drive an old car


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When you can smell the paint cooking off your engine.

 

Overheating must be a Northern term. Here in the South, the condition is just plain "damn thing is running hot and boiling the water out".

 

Gentlemen, this has been a VERY good discussion and thanks for keeping it civil. Usually tossing ideas around like this leads to hot heads (no pun intended). Hopefully the info here will enlighten others who seek the answers to cool running. I'm going to try the Evens product in my blown flattie, and I'll let you all know how that works out.

 

I've never had a car that repeatedly overheated. My first hot rod was a 58 Plymouth that I put a 383 into. I spent a lot of money trying to get the gauge to run cooler. It turned out that I never had a problem. The sending unit in the 383 caused the temp gauge to register too high. I put the sending unit in it from the 318 and it was just fine.

My flathead ran great with 180 stats, stock radiator and unpressurized. never a problem. I don't believe in special mixtures to reduce heat. Snake oyl to me. I always run as much advance in the timing as the car will take and start easily when warm. So running too retarded was never a problem either.

Too many people look for easy answers like what coolant to run etc.

 

Volcano zone, I was always scared more about overheating than anything else when I was younger. The thought of getting stuck in traffic on a 100 degree day on the interstate or NY city traffic was never appealing. I've since learned high temp doesn't always mean over heating. My 440's always ran hot and then hotter. I've done the whole radiator thing, new fan clutches, etc in the quest to it down. Mostly I find running at higher than the max speed limit helps, but once I leave the highway to the country roads the cars cools back to a respectable 190-195 range. Of course the cooler temp for me means I'm not turning into a puddle behind the wheel. They never boil over but when they're in the bake zone I am too.

 

I've spent the last two weeks trying to keep my blown flattie cool. Restrictors, no restrictors, pump overhauls, stock timing, advanced timing, retarded timing, stock jetting, fat jetting, push fans, pull fans, both, cardboard ducting, catch tanks, no pressure cap, 4lb. pressure cap...

My engine is stuffed in my heap tighter than a sausage casing with not much grill or radiator area. I'm running about 210F now on straight water. Shooting the heads with a infrared thermometer is usually about 10 degrees lower than the gauge reading. I think I'm going to put some coolant in, a 7lb. cap and just drive it.

Might anyone have a manual that specs the cooling system capacity of a '37-'40 Ford with a V8-60?

 

better off leaving it straight distilled water and a higher cap , a/f is not a good heat transfer chemical , water transfers the heat better and faster . only thing a/f is good for is protecting it from freezing and some corrosion protection and pump seal lubrication ( which you can buy seperately )

 

It's gonna run hotter with coolant

 

If it isn't steaming it isn't overheating !

 

I was thinking coolant because it raises the boiling point a bit. I have a cut down '60s Cadillac radiator, how high a pressure cap dare I run with that and the flathead using straight water?

 

has to do mostly with the materials and condition of the radiator as too much pressure can expand the cores and shrink the area between the core so air cannot flow as well thru it . they used to run 16 pounders back then . if the rad is in good shape I would say run that or atleast 10 PSI

 

OK I'll try upping the pressure, radiator is in good shape. They say a cracked block will cause hot running but both heads read the same temp with an infrared gun, one side would be hotter in that case I would think. If it runs without popping a 10 psi cap I suppose that's good enough.

 

A big problem I see is guys will modify a radiator "to fit" the size of the shell/grill or chopped stance of their rod...IF you're going to run a shortened radiator you need to have it made thicker and with more passes to keep the air flow and surface area large enough to allow the heat to escape. A good shroud around a properly sized fan helps alot too. I'm running an AOD tranny and needed a cooler for that as well, so I had a custom radiator built to include that. It's fully shrouded with a large fan. we'll see what it does when the weather warms up.

 

wait..what? mineral oil for coolant? never heard of or seen this before.

 

I don't care who you are, that guy right there is funny!

 

How many rows on your radiator? I have a 3 core copper brass now. Thinking about 4 core but not sure how much more efficiency that adds. My grille area is small (but so is my engine, v8-60). I can remove the front fenders and grill, runs much cooler.

 

Ya'll ever watch Roadkill on the motortrend youtube channel? Those guys favorite thing to do is take the hoods off of cars when they start overheating. Seems to work in a pinch.

 

Yep I'm sure that helps. I'll know if I ever get my hood back on. I haven't run it since I put the blower on, need to cut a hole and fighting cooling woes first. It's scheduled for a dyno session today, maybe I'll learn something with timing/jetting that helps. If it holds together.

 

mineral oil as in motor oil , you have mineral and synthetic .

but there are O/T vehicles that use the engine oil as a coolant , and I don't mean vw's, suzuki motorcycles use it and run it like water to cool the motor down . was only for a few years they did this .

 

Blowby...it's a 5 core and fits in a stock 31 shell, the tranny cooler is built into the bottom edge, so I lose a little there but it looks neater than an aux. cooler.

 

I'm an advocate of 220*f as the upper-limit of consistent operating coolant temperature. Most engines can slide as far as 225-227*f without fuss, but I don't want to see one spend any time there. As long as the coolant pressure is maintained and the coolant is not boiling over (puking as some might say), that is safe. I'm more concerned with engine oil temp than coolant though, and that depends on compression, driving conditions and force-induction vs. naturally-aspirated for what is healthy.

Each engine will have a different 'happy point', some like it colder, while some like it hot. Jeep 4.0's like to run on the hot-side, staying above 190*f.

Be cautious with multi-core radiators. In the Jeep community there is often a lot of hypothesis about how amazing they are. The ones that are available use separate tubes for each core instead of a single elongated tube that spans all cores. This leaves a lot of cooling potential and flow on the table for the sake of cheaper manufacturing.