[brianl269]

After overheating in a prolonged idle situation (10 minutes at idle on a 80 degree day) I am completely redoing my cooling system in my 65 Pontiac Tempest Custom Convertible.

I have ordered the following:
1)Desert Cooler 4 core radiator

2)New water pump

3) New thermostat

4) Radiator shroud

5) Upper & lower hoses

The last item I am considering is replacing the stock fan with a stainless flex fan and eliminating the fan clutch. Is this advisable? Any experience with flex fans from anyone?
Is their anything I am missing that may have lent to the overheat ptroblem?

Any input appreciated!

[brianl269]

After overheating in a prolonged idle situation (10 minutes at idle on a 80 degree day) I am completely redoing my cooling system in my 65 Pontiac Tempest Custom Convertible.

I have ordered the following:
1)Desert Cooler 4 core radiator

2)New water pump

3) New thermostat

4) Radiator shroud

5) Upper & lower hoses

The last item I am considering is replacing the stock fan with a stainless flex fan and eliminating the fan clutch. Is this advisable? Any experience with flex fans from anyone?
Is their anything I am missing that may have lent to the overheat ptroblem?

Any input appreciated!

[Bob Kazian]

Brian,
This may seem like a silly question, but how do you know your engine is overheating?

I have seen many people go through a lot of parts replacing because their gauge showed the engine was hot. They later found that the gauge was reading incorrectly. Now if your engine is popping, jumping and carrying on...that's another story.

Have you confirmed that your engine temperature is really too high?

[brianl269]

Thanks for your input Bob!
I have not confirmed the actual temperature of the engine, but my radiator was definitely popping and sizzling as you described. Further the pressure became so great in the radiator that when I lifted the hood and walked away it blew the lower hose free of its clamp and sprayed antifreeze and water like "Old Faithful" all over my car. I'm pretty sure I'm in an overheating situation, I just need to make sure i'm attacking it the right way. Do you think I'll solve it with the items I described?

I am a Pontiac rookie, although I LOVE my new (old) Tempest!

[Kurt Zimmerman]

Brian,
I think you're on the right track with the hoses, radiator, new pump never hurts, etc. When I replaced my thermostat, I went with a 160 degree, just to get things circulating right away. I got the best improvement with the shroud. I would wait on the new fan and dumping the clutch. The original engineers knew what they were doing when they designed your system. New belts are a must too, belts don't always squeek when they slip, and if they're slippin', that new pump won't be pumpin'.
Good luck with your project.
Kurt

------------------
"folks nowdays just don't do nothin', simply for the love of it..."
Don Henley

[brianl269]

Thanks Kurt!
I didn't even think about belts. I will replace those as well. I ordered a 180 degree thermo as that was all i found at Ames. However i may go to the local store and purchase a 160 degree. I also noted a good drip from the weep hole and that's what led me to replace the pump.
Thanks again for the advice.

Anyone else have a thought on the
stock-vs-flex fan issue?

[6567GTO]

Years ago I put an aftermarket flex fan on my '69 goat at the time because she was running a little hot. Well it turned out that she ran even hotter with flex. There are different designs out there though. I may have just picked a bad one. The fan would flatten out at the slighest rise in RPM and resrict the airflow coming through radiator. Like Kurt said those Pontiac engineers new what they were doing. Stick with the stock fan for now. Good Luck,

Phil

[Bob Kazian]

Brian,
I would go with the stock fan and clutch. however, you must ensure that the thermal fan clutch is engaging as the temperature rises.

In a related cooling item:
I just finished installing a Ram Jet 350 (factory fuel injected) crate engine in my
S-10 pickup. I had a ZZ4 carbureted engine and wanted fuel injection for it's advantages.

The ZZ4 with an Edelbrock Alum Water Pump and 180 thermostat never ran hot and cooled fine for the 3 months that they were on the engine.

I switched the water pump and accessories to the new engine and I started getting temperature readings that went up to 250 deg (not all the time, but all of a sudden - increased rpms, more flow, brought the temp down imemdiately).

I had all my "expert" friends look at it as well as some GM technicians. They gave me plenty of bizarre suggestions on what to do.

Then I had the truck on a lift at the muffler shop and observed that the water pump was leaking out of the weep hole. I changed the water pump and the problem went away.

I now suspect that the impeller was loose or somehow not turning all the time at slow rpm.

Moral of this story:
It's not always the obvious that causes life's problems.
Good luck with your cooling problem.

[brianl269]

Thanks all!
I will keep the factory fan and clutch set-up and see what happens after I make all the other changes. I will post results by the end of next week.

Brian

[bus15241]

Brian,

My father-in-law had a flex fan. It was extra noisy (roaring sound) and seemed to put a drag on the engine. Also, several years back, my own dad put a flex fan on his chevy and ended up with a dent/hole in his hood. What happened was one of the blades broke loose and shot into the hood. Stick with a good working clutch type fan. -Steve

[Old Man Taylor]

I have a factory flex fan on my GTO. It has been on for about 25 years. Shift RPM is 6400, and my hood is still flat. It does make a roaring sound, but I cannot hear it in this car. I would not trust any aftermarket flex fan. On the cars I have that have clutch fans, I use the motor home clutch.

------------------
Jim

[brianl269]

Just wanted to bring some closure to this topic. After performing the above mentioned items my car is running cool as a cucumber. I can't force the temp higher than 172 degrees no matter how long i idle. I went with a Hayden flex fan and spacer. So I have a nice factory original 7 blade 19 inch fan and perfectly good fan clutch if anyone is interested.

Thanks for all the good advice everyone!

Brian

[Engine-Ear]

Old Man Taylor,

To your point about aftermarket fans, I have been using Flex-A-Lite fans on cars for years and have noticed a consistent 15+ degree drop in steady state operating temp. They are one-piece 6-blade designs made of some form of nylon blend. The fan is available in 16", 17" & 18" flavors, is US made, and is guaranteed to operate without detonation at 8000 /steady state/ RPM. And they are affordable at $20 retail.

I have had crappy luck with the riveted-razor steel fans, including an unplanned louvre in the hood.

Is the OEM, "factory flex fan" design you cite still available off the shelf from GM? What is it's P/N; I'd like to try one out...

Matt in Milwaukee

[78 GHOST]

I was trying to find an elusive vibration on my 400 powered '78 T/A with a factory clutch fan. The car would vibrate pretty badly at 1450 RPMs up 'till about 1600 RPMs under any circumstance.

Well, I jerked the whole fan, pulley, belts, etc. and the vibration totally went away. After re-installing the fan and carefully running at the above RPMs, I could actually see the vibration in the blades of the fan. At other RPMs, the fan was describing a perfect circle, at the trouble RPM I could see visually how the fan would start to vibrate.

I am now looking for a replacement flex fan to hopefully cure my vibration. My last GTO had a flex fan and ran wonderfully in the Arizona desert. I feel that the factory fans/clutches are fine if true and balanced. However, due to their great rotational mass I think they are much more sensitive to small balance problems, drop 'em once and write 'em off.

Not that I'm the expert, but for the cost of a replacement clutch, I can afford 3 flex fans. I think I will try the Hayden as that is what was on the GTO.

I was wondering if anyone had used successfully an electric fan(s) to replace the belt driven fan??? Thanks, Matt [img]/infopop/emoticons/icon_smile.gif[/img]

[Colorado Bill]

Matt in Milwaukee,

Wow--what application are you using the black nylon fan in and seeing 15-degree temp drops? I've never considered one of those, but I've never heard anybody's experience with them until your post, either.
I'm using one of Flex-a-lite's standard flex fans, and it flattens out as soon as I open the throttle. Their catalog lists a new 7-blade flex fan that looks a lot more heavy duty though: http://www.flex-a-lite.com/auto/7blade.htm
Anybody tried one of these? I'd also be interested in the part number/application for a factory flex fan.

[Old Man Taylor]

Engine-Ear - The only one piece plastic (or fiberglass) fan I ever used did not move much air. It also did not bend very well at higher RPM. The factory made several riveted steel flex fans. I have two of them at home. I will check the numbers on them and then post them. I have run one on my 64 GTO for over 25 years. I liked it so well I added one to the old 69 Catalina wagon that I had. I installed a 428 with a 65 tri-power and a 067 cam. It took my awhile for me to realize that the roaring sound I was hearing was the fan. I could never hear it in the GTO.

[Old Man Taylor]

Here are the numbers I got off of my flex fans. 480033 - This is the 5 blade 19" flex fan I run on the GTO. 9796135P/914182 - there are two numbers on this fan. It is a 7 blade 19" fan that I ran on my station wagon. 149592 - This is a 5 blade 18" fan that I got to run on my El Camino. I don't have that car anymore.

------------------
Jim

[KS circutguy]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Colorado Bill:
Matt in Milwaukee,

Wow--what application are you using the black nylon fan in and seeing 15-degree temp drops? I've never considered one of those, but I've never heard anybody's experience with them until your post, either.
I'm using one of Flex-a-lite's standard flex fans, and it flattens out as soon as I open the throttle. Their catalog lists a new 7-blade flex fan that looks a lot more heavy duty though: http://www.flex-a-lite.com/auto/7blade.htm
Anybody tried one of these? I'd also be interested in the part number/application for a factory flex fan. <HR></BLOCKQUOTE>

Just got one from Flex- a-lite,cost $47.00.
Looks like a nice piece,I'll be installing it in my 80Bird' this weekend and let you know what I think!
And thanks for the link and part # Matt.
KS-out.
http://photo.starblvd.net/zanko20


[This message has been edited by KS circutguy (edited 05-16-2001).]

[MitchGM]

KS.... I've had a flex-a-lite 7 blade fan on my car for years. You need to make sure you have the proper spacer for it to work efficiently. The first time I installed it, the spacer was wrong and the fan was too far out of the shroud. I installed another one that was too far into the shroud. I found one that was perfect. Half in and half out. Since then I have never reached temps of 210 or more on my car. I have a 160 degree thermostat, 4 core Harrison. My usual temps range from 160 to 195. On really hot days, I might see 200. But very rarely.

[This message has been edited by MitchGM (edited 05-16-2001).]

[KS circutguy]

Got the 4 row cleaned and installed the new Flex fan #1818,installed a 2" spacer,car runs at 170 at 3000rpm down the highway!

And won't go over 180 in traffic,pulls it down to 170 with afew blips of the throttle,not as noisey as old design.
In short,I really like this new flex-a-lite fan. [img]/infopop/emoticons/icon_biggrin.gif[/img] C-70-out.