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Cooling Problem

M

MLGower

Guest
How much of a difference does it make to have the fan shroud on the radiator? I have my 78 setup with a electric fan and removed the Clutch fan after it exploded and took the shroud with it. My Vette now gets up to 195 degrees, but then starts creeping up to around 240. is this because of bad air flow, or is there something else I should be looking at? Thanks for the help!!!!

Michael :w
 
C

cmegga

Guest
I have been going threw this for the last two year with my car. I just had it rebuilt and boared 20 over so its ever worse with temp now.

I have done the clutch fan, water pump, theromostat, new hoses and have the electric fan permently on.

But the best result I have seen that made the biggest drop in water temp has been a additive from Prolong.

Its called "stops overheating,, 40 below " . It was about $26 a can and 1 can with just water in the radiator and I droped between 20-30 degrees in coolant temp. Definitly the best solution I have found for the cost invested.

You can get it threw Jegs or i found it at my local AutoZone.
 
M

MLGower

Guest
My temp was a solid 180 before the clutch fan exploded and went through the radiator and fan shroud. The radiator has been repaired, and has excellent flow, but the only other changes were the electric fan and no shroud. I just can't figure out why the temp creeps up to 240. Strange..... I will try that prolong stuff though, It should help keep it cooler. Thanks!!
 
C

c4ever

Guest
The shroud is necessary for proper cooling. I would replace it and observe results.

Carlo
 
C

cmegga

Guest
I would thinks so. That plastic shroud is the only thing that directs the fresh air to the engine compartment. With out that it is sealled off pretty good under there for very little air flow.


I would definitly put that shround back on.
 
S

Stingray72

Guest
Will the clutch fan shroud even work with your electrical fan? there should be some kind of shroud, but it should be designed for your fan. Placing the big bulky clutch fan shroud over an electrical fan that's mounted flush against the radiator might not be the best solution.

Good luck.
 
M

MLGower

Guest
I Think I figured this out. Because of how the engine bay is configured on the corvette, you end up with a big air gap on the engine side of the radiator at the bottom of the car. With that big gap, the air flows to the wrong side of the radiator, creating a high pressure area on the engine side of the radiator, preventing air flow through the radiator as it's supposed to. The fan shroud blocks the gap at the bottom of the engine bay, creating a low pressure area on the engine side, and then allows the air to flow through the radiator from the front. I've noticed that if I let my vette sit and idle, or run it for a while at 3000 rpm in park, that it cools itself down. But when I drive, either at highway speeds or in town, the temp tends to creep. even on flat ground. I'm going to be picking up the new shroud today and I'll let you know if I'm right about this.

Michael
 
C

ccflorida

Guest
Question

What causes the clutch fan to explode??? Old age!!..... Should they be replaced after so many years??? I have the original in my 79 and it works fine. After reading this I begin to worry..
Thanks
 
M

MLGower

Guest
I have NO Idea. The clutch assy appears to be intact, but I ended up pulling the fan out in 5 diffrent pieces. It could have been that the fan was off balance, who knows. Funny thing was, the vette actually ran / runs better with it off!!

Michael
 
P

page62

Guest
When I had my A/C overhauled, the shop told me my clutch fan was bad. That helped me feel better about the price I paid for everything.

But if your clutch is 23 years old and working okay, I wouldn't lose too much sleep over it!
 
M

MLGower

Guest
Yuk!!! Sounds about like what happened to me. Except for the Busted Water pump. :)

Michael
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
I assume that all other components of this car's cooling system are functioning properly.

I'm also assuming that this creaping up to 240 occurs in traffic or at low speed.

A shroud is necessary any time the fan(s) are set back from the radiator core.

Many aftermarket elec. fans attached directly to the core. If this is the case with your engine, you might need two fans or a single fan that flows more air.

Even with elec. fans of proper flow rates, you also need to prevent cooling air flow from bypassing the radiator. The production cooling stack used sponge rubber seals at the top, bottom and sides of the radiator along with one between the hood and the core support. All of these must be present for good cooling.
 
M

MLGower

Guest
Hib,

Yes, All other components are working fine. The creeping occurs at highway speeds and I actually cool back down when in traffic. I have the biggest cooling fan I could fit also.

I just installed a front spoiler last night and today, It's stays nice and cool. I couldn't get the temp above 200 degrees pushing it up a 6% grade 2 mile hill. I figure the problem has to do with there not being anything to block the wind from getting further back into the engine bay, bypassing the radiator entirely.

Thanks for everyone's help on this. I can finally take my baby out in the heat!!!!! Now if I could only fix the weird noise in the rear end...... :) Work in Progress

Michael
 

topless82vette

Well-known member
Joined
Nov 1, 2001
Messages
910
Location
southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
Ive seen alot of responses to overheating problems but there one cause that Ive seen happen that nobody has ever mentioned and that is the rusting of the lower radiator hose's inner spring, Ive seen a couple of cars that this has happened to and the spring went up into the pump and immediately took out impeller blade/blades causing very bad flow in some instances and completely causing impeller seperation on one ... I personally think this inner spring idea was a bad idea and hose collapsing should have been cured another way .... does anyone know approximatly how much it would cost to completly do my cooling system with silicon hoses and where can I purchase the hoses
 
R

rbyrne

Guest
I'm guessing that rad hose spring rusting is peculiar to Southern cars where it is imagined that anti-freeze is not necessary. If the rad hose spring rusted, what shape is the rest of the cooling system in? Overheating at highway speeds(only) is typical of a missing lower rad hose spring.
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Spoiler

Yep, I was getting ready to ask you about the front spoiler. It is critical for cooling the car at speed. In extreme cased you can always put a 1992 style Firebird radiator air dam under there. It has to be modded, and you bolt it on the bottom of the radiator core support. It is almost not even seen from outside the car, but it picks up that last bit of air and rams it in front of the radiator creating a low pressure gap behind it. That way air at highway speed goes through the radiator and back down around the engine. Plus, the F body spoiler is disposable, so banging it up on curves and bad spots in the road won't hurt anything.

In fact, if you owned a third gen F body, and lost that lower spoiler you would overheat in the first couple of hundred yards out from your driveway due to the poor natural air flow in those cars.

Glad you fixed it!
 
M

MLGower

Guest
Chris,

Yea, I'm quite happy about that spoiler. I'm only using the flexable stock ABS spoiler on it. This car has been abused :(. The guy that owned it before me must have done too much crack for letting it go like this. I took it out yesterday and ran it hard up a long grade in the heat (90's) and couldn't get it above 205. I think my next step is to get the noise out of the rear end. I just replaced the berings on the right rear spindle last weekend, and will be doing the left this weekend. What a pain in the a**!! I hope this fixes it. I have a LONG way to go to have this beasty where she needs to be, but I'm having a lot of fun doing it and learning about it!!! :)

BTW, I love the pics on your 69. Are you going to do a write up on how you did a few things on her? I would love to see how you did the Gauge set. Truely a beautiful car.

Michael :W
 
D

D@D74-454

Guest
overheating problem solved on 74 big block

Hi all
We were running hot especially on the highway. We flushed our rad several times, changed noisy water pump, removed clutch fan and replaced with a direct drive fan used for race cars ( not a flex fan ) and put on a new fan shroud ( someone before us had cut off the top and sides of shroud ) We lowered our temp by 25 -30 degrees. We run steady now about 200 and that's good for a big block. Even with the hot humid weather were having! The shroud makes the biggest difference!!!!
 
C

cmegga

Guest
wHAT Spoiler ??

Are you guys refering to the spoiler that is molded into the bumper? Or a part that runns behind it??

I am too still having heat problems, it seams to be fine around town from light to light, but on the highway for a 30 min or over haul it heats right up to 240 or so.

The spoiler I have behind the bumper is in place, but has previously been cracked and is attached in the middle with wire. Could this be part of my problem ???
 

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