Heidi another question

[crebo]

I read in one of your threads about you going to a flex fan and the difference it made. I have a Big Block and the temp is finally coming down. I still haven't ran it with A/C. I also live in the desert. It hasn't been around for the blistering temps (105-115)

Is the fan really loud?
Does it look pretty good in there?
How hot did your car run before?

Thank you very much
Crebo

 

[78SilvAnniv]

Hi Crebo,

Many people discredit the flex-fan with really doing anything to cool down an engine...but for us...it was the ONLY thing that cured our run hot problems.

We lived in California, a central farming valley north of Sacramento with summertime temps of up to (and usually over 100 degrees). When summertime rolled around I was forced to slow down. I could not drive the 70mph limit on the fwy. Wintertime was fine, but if the temps went up, so did my water temps.

We replaced fan clutches, water pumps, belts, hoses, radiator, fan shroud, tuned the engine...everything we could think of and nothing worked. After 5 years of battling this run-hot-summer problem, we replaced the engine with a GM crate engine and repaired the non-operable AC.

The engine still ran hot if I traveled fast, but if I used the AC it shot up to 240 in a hot minute! We moved to Washington state, and I did not use the AC at all for 3 years. Running temps would get a little warm driving up the grade in the summer, and if I kept my speed down, the water temp stayed down. This was now 3 years after the new engine.

We moved to Georgia and the first summer here, it would still run hot if I drove fast. Kenny and I bought a flex fan (the only thing we changed) and immediately it fixed our run hot problems.

I can drive at any speed, at any time of the year AND use my AC in town or on the hwy! We also made a drive to Helen (mountain roads) with 3 other vettes ('77, '88 & '96) and Kenny drove the 78 like we had never driven her before... rpm's at about 2500-3500, peaking at 4500 for almost 20 miles of uphill curves and switchbacks and she never even came close to 200!

We have now had the flex fan on the 78 for about 1.5 years and have never overheated. The fan is louder than the fan clutch, but not in a whiney sort of way, I think it sounds nice. I like hearing it, and knowing my radiator and engine compartment are getting plenty of air. The one we purchased (at a speed shop, $40) is a light blue with silver colored blades, metal.

Previous temps: (hot summer temps)
195-200 degrees at 55mph
210-225 degrees at 65mph
240 with AC at any speed *I never tried to see how much higher it'd go
winter - I could drive 70mph and temps would stay below 195

After flex-fan: (hot summer temps, AC & cool winter temps)
never over 195

Good luck with your big block, and I hope my information helps you. It worked for us.
Heidi

 

[crebo]

Thanks Heidi!
I think I will give it a try...
I'll post the results
Crebo

 

[78SilvAnniv]

Please do post your results...

I would like some justification, proof that the flex fan works when all other avenues have been exhausted.
Heidi

When purchasing a flex fan, be sure to get the proper spacer. The Corvette has a different spacer than other vehicles.
I'd also recommend purchasing a high-quality one. Cheaper models have been known to throw blades through the hood.
H

 

[Vette/Berlina-coupe]

-from BerlinaBob: -Provided the Radiator and Thermostat(180* not the exaserbating EPA-imposed 190*) are known to be flowing properly, no debris is found obstructing air-flow (blast water from a garden-hose forward through the honeycomb), and your Fan-shroud is necessarily fully-encircling for peak-efficiency.... some careful extensive-tests have been conducted on this problem, --showing the dastardly Fanclutch being the culprit! Best "remove it entirely" (it was put there only to reduce fan-noise by slipping of the thick/silicone-fluid therein) and insert a superior Flex-fan in its stead (I prefer the comparatively light-weight quality-fiberglass type(15-years now, -but watch out for "cheapo" imitations) but less desirable heavier/stainless-steel types are commonly available [or alternatively: -by permanently locking-up Fanclutch via insertion of two oppositely arranged (for balance) #10/sheetmetal-screws through it]. However, if you are running a big-blockV8 with a sm.block-radiator, such radiator is to thin, so needs to have a much thicker four-layer Radiator-core (which is best for all Corvettes anyway). And finally, remember that air-volume flow through the radiator is reliant upon ability of your engine-compartment to expell the heated-air efficiently, --so make there has been nothing added that would cause excessive restriction of air sweeping both in and out of the engine-bay (some experts even add exit-louvers if air-flow is restricted. Finally, Distilled-water is found the best most efficient coolant, so use antifreeze-solutions sparingly (25% is enough, unless in freezing-weather), as excessive antifreeze-admixture will cause an engine to overheat... B.B. :dance

 

[78SilvAnniv]

Welcome Bob!

Very interesting Berlina in your sig pic! She looks very classy.

Welcome to Corvette Action Center, home of the 'nets friendliest and most helpful corvette enthusiasts!

I enjoyed reading your post, finally feeling justification for my switch from fan clutch to flex fan. I would be interested in knowing where you received your facts, as this is the first time I've seen a post confirming my thoughts about the fan clutch and flex-fan.

Vindication feels good!
Heidi

 

[Vette/Berlina-coupe]

Re: Welcome Bob!

Very interesting Berlina in your sig pic! She looks very classy.

Welcome to Corvette Action Center, home of the 'nets friendliest and most helpful corvette enthusiasts!

I enjoyed reading your post, finally feeling justification for my switch from fan clutch to flex fan. I would be interested in knowing where you received your facts, as this is the first time I've seen a post confirming my thoughts about the fan clutch and flex-fan.

Vindication feels good!
Heidi

------------------------------------------------------------------
BerlinaBob-here: -Yes, I recall the FlexFan-unit you have installed, believe it is the one with a blue-colored hub with arms extending outward in support of rivited/Stainless-steel blades made sufficiently-thin as to yield to progressively flattening-out with increased RPMs; --and that low-pitched hummm just means it is doing its job (unlike the relatively quieter FanClutch-units, which are an inherently-defective engineering-design!). The FanClutch concept has an adverse-defect, in that as one's engine becomes hotter, the coolant within the radiator is heated more causing ambient incomming-air to expell from the radiator-honeycomb ever hotter; --and this acts to heat the viscous-liquid within the central-hub of the FanClutch, and hence antithetically (oppositely) thinning the ingredient instead of more appropriately thickening-it you see!! Oh, they place a bimetalic/thermostatic-valve at the central-front of those FanClutch-hubs in effort to counteract this inherent flaw in design, --but it is to-little to-late! I really detest those FanClutches, owing that it is a classic case of dumb-engineering; --that visually fools everyone into thinking it is well conceived--- Wrong (feel the FanClutch's-drag when an engine is sitting-cold in the morning, --its drag is "bass-ackwards" maximum, instead of being minimum while your engine is cold and the fan is not even needed (that's where the electric-powered Fans really have it right; --they don't come on at all untill your engine is warmed to about 175*f)!! Your FlexFan is precisely right in its engineering principle-- that is, it is positive-acting (no slippage) and hence entirely predictable and reliable in function; --while the blades automatically yield to the density of the air as well (at higher altitudes, the air is less-dense, so the blades yield less, maintain a steeper pitch-angle) as to necessarily move more thin-air! The quality HD/all-fiberglass FlexFan I have (somebody must still make a good one in fiberglass), is probably only 10% the weight of your quality all-metal unit, --so it has the advantage of consuming less energy (weight takes energy to move, -even in a circle!), plus I can leave the fanbelt rather loose because of its requiring less-energy to move and will rev much more readily owing to its light-weight. Unfortunately, it is'nt at all as "techie"-looking as your spiffy gleaming stainless-steel iteration! Bet this is more than anyone really ever wanted to know about this issue, --but, perhaps we shall save a few souls from going through the hell (expense and aggravation) of an unexpelicably overheating engine. Additionally, in those cases where even a four-layer radiator-core is still overheating, --one can even install a six-layer core, plus a larger surge-tank (reserve coolant capacity) will definitely do the job (if not, -there has to be some hidden restriction of the coolant-flow, -preventing sufficient circulation)...

 

[78SilvAnniv]

This is not too much information!

I am enjoying reading about it because it confirms my ideas about the flex fan over the fan clutch!

We battled the run hot problem since my husband purchased the 78 in 1990. The flex fan fixed all that in 2001! Just think: Eleven years of summertime driving enjoyment hindered because we did not install a flex fan earlier. ad

Thank you Bob, for the information.
Heidi