First, my car has never overheated. NO issues at all with overheating.

A friend was playing with my engine, so to speak, and mentioned that I should replace my 4-blade fan with a 6-blade fan, and he prefers the flexible fans (I think he had that in his Fox body).

Several people told me flexible weren't good as they bent at high speeds, but I don't go that fast and rarely take highways, so that wasn't a huge concern of mine.

However, someone else mentioned last night that the inline 6 only requires 4 blades for the simple reason that the engine has to reach 200 degrees to work properly, so if I try to cool it off a little more, it won't reach potential and will burn out and cause me serious problems.

If it ain't broke, don't fix it -- I know, I shouldn't change the fan. But I'm curious if he's right about the engine failing if I cool it off too much, just out of general curiousity.

 

I have a stock, '65, 200ci, 6cyl car and dive in 100 degree/100% humidity conditions. (180 thermostat)

I replaced the heavy, fixed, 4 blade fan with a lightweight, metal, flex 4 blade of good quality. It's strong enough to pull air at low speeds but flexible enough to flatten out at higher rpms and pull less hp.

It's worked really well for me for years now, and I couldn't be happier with it. I also don't need a shroud anymore. Neither do I need a puke tank. I just run the stock overflow tube, but it nevers pukes a drop.

Of course, the MOST IMPORTANT improvement was the installation of a good quality 3 ROW RADIATOR. All my cooling problems went away even in high heat, crawling traffic jam conditions.

re: 200 degree optimum preformance
I don't know anything about that being a fact, but I do know the 180 degree thermostat seems to work perfectly in my stock engine. I'm guessing it's operating between 180 and 200 degrees with that thermostat.

Hope this helps a bit, Pam! Good luck!

 

6 blades are generally more efficient (look at early model WW2 planes (2 blades) vs late model like the hawker seafury (5 blades)

The flex-a-lite fans are suppose to flatten out at high rpm thats their job as this causes less drag on the engine and at high rpm (and speed above 20mph) the fan doesn't do anything as the airflow over the rad due to speed of car is enough to cool the water (no fan required)

Finally you can not have too much cooling at the radiator (unless you freeze the water inside of it) because engine temp is controlled by the thermostat its job is to let the right amount of cold water into the engine block.

-Gun

 

If you aren't having any overheating issues I wouldn't change anything.

You do want the engineto run warm enough such that moisture boils out of the oil (which typically runs hotter than the coolant). 180° thermostats always worked well enough for that, and that's what's in my thumbnail car. Higher coolant temperatures (and thermostats) are a tied in with emissions control, most newer cars using 194° or so. Which as a side note means that if you're subject to a state emissions check even an early car would have an easier time getting through with a higher temperature thermostat temporarily installed.

I've run a flex-fan before, but I don't particularly like them. Too noisy, for one. They aren't as efficient, overall, as a clutch fan (saw a test report on this once, but don't remember where it was). And SCCA autocross rules flat outban them even in otherwise completely stock cars, which ought to count for something in terms of durability and/or safety (it is in the 'Safety Inspection' section of the rulebook).

Norm

[IMG]local://upfiles/62186/A63CFCF68C954E069DC0021B31BC7D4E.jpg[/IMG]

 

Thanks, you guys rock! The mechanic who told me about the 200 degrees is an older err gentleman who feels he knows it ALL about cars, women have no place in the garage as it's a man's world, and people on the Internet are full of it.

Several times I've challenged him on things he has said (after checking with y'all here) and he won't admit he's wrong.

I will leave things as they are, totally stock, until something goes wrong.

 

Hey Norm-

FWIW, I pay particular attention to your posts. Almost always learn something and your input is usually thought provoking.

Question - boiling points of fluids are often (not exclusively) attributable to the number of particles dissolved in them (if memory serves me correctly - I believe it is a colligative (sp?) property... forgive me but it's been decades since I have thought about this.) When some fluids boil off, doesn't that increase the number of particles in solution and raise the boiling point? Or do they precipitate out and contribute to sludge along with the cleansing property of the oil and increase sludge? Or are all these things true and it really doesn't make that much of a difference because the amount boiled off is minimal?

Very interested in your take on this.




"You know Diane, writ of Habeus Corpus and all that not withstanding, my point remains moot" - Clifford Clavin, US postal worker.

 

re: flex fans

I hung my heavy, 4 blade, seemed-like-iron factory fan on my garage wall and replaced it with a good quality, metal flex fan with 5 blades.

Not only does it draw more air at low rpm's, but the reduction in weight gave me a noticeable increase in engine power.

I wouldn't discount all flex fans especially those used in stock, street-driven applications.

It has performed so well over the last 4 or 5 years I wouldn't think of going back to that old metal device which was designed and engineered sometime around the early 1900's.

btw: Norm, I may not have looked hard enough, but I couldn't find a fan/clutch combo that fit behind my radiator with enough clearance.

 

I wasn't looking at boiling point effects as much as at what many substances become when they're in a water solution - typically acids. Mild overall, considering the oil volume, but there in fluid form.

doc540 - every car is a little different as far as room up front is concerned. Hard to believe that my thumbnail car in my previous post needs about a 2" spacer with that short of a hood.


Norm

 

Mustdoc i believe your right about the coagulation properies and boiling point.

The water in the car should never boil even if temps are well above 212f. This is because the radiator cap and entire cooling system are under pressure (from the hot water) more pressure means higher boiling point.
if you remove the rad cap and the water temp is above 212 it will boil as soon as the pressure drops to standard atmosphere.

At about 33,000 feet air pressure is so low that blood (98.6f) will begin to boil bad news if you don't have a space suit on

Gun

 

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