Does the wrong fan clutch affect cooling ?

When cold, the thermo clutch allows the fan to spin 1 time for every 4-5 revolutions. At peak operating temperature, the clutch locks up & the fan starts to spin faster & faster until it is going full 1:1 ratio. If the clutch is bad & locked up, and the fan is spinning 1:1 all the time, it will eventually start putting extra stress on the water pump bearings, and it may start wobbling.

I have a 5-blade fan on my 430 with a good clutch, and the temp gauge in stop/go traffic on a hot day rarely gets to 220 degrees (50% between C & H). Most times it is right at 200 (25%).

Check it when the engine is off & cool, and ensure it spins freely & there is no lateral play. Make sure there's no oil on the hood above the fan...when the clutch goes all of the oil leaks out. When the engine is warm, check it again & see that it has tightened up a little more but still spins smoothly.

The clutch is only a $40-50 item...go to oldbuickparts.com & pick 1 up if you need it. If yours is still fine, grab a spare. Can't hurt, parts for our Buicks are rapidly becoming scarce.

 

Thank you everyone for your input. I learned a lot. My next move will be to get a standard thermostat controlled clutch for a 455 and a 20" fan. My fan is already located 1/2 in and 1/2 out of the shroud. I'll start with the simple stuff here and work up if it's necessary. I'm trying to get the Regal running cooler when cruising cause I want to take it to the Frankenmuth Mi. Car show next sept. and cruise the Main Street with the other noise makers. If these changes don't do it I many be back on here next spring when I take it out of winter storage. Thanks again everyone. Roger

On The Eighth Day God Created Buick

 

Oxalic acid flush of my cooling system took my temp down 30 degrees.

 

Oxalic acid? Never heard of it. Where did you buy it?

[Edit]https://www.amazon.com/OXALIC-Ethan...7MZ6/ref=sr_1_3?ie=UTF8&qid=1508023230&sr=8-3

Ahh...Wood bleach.[/EDIT]

I presume the acid scoured-out a bunch of rust and scale; cleaning both the engine and the radiator. Apparently the acid plays well with all the various metals in the cooling system--cast iron, steel, copper, brass, aluminum.

Nice success story.

 

The above picture is the correct Thermostatic Clutch Fan Assembly along with 7-blade 18" fan used on the 1970 GS 455 Stage1 with A/C and HD cooling

 

That's exactly what I will look for Sport 1 thank you very much. Roger

On The Eighth Day God Created Buick

 

A little about fans (and what transfers from props and jet engines...)

The fan, shroud, radiator, thermostat (and clutch if present) when working properly together will provide adequate cooling in most environments.


Case.

I purchased a 1968 Skylark with a 350-4 ST300 and it had a 16" flex fan with a 19" shroud opening.
It ran 210-215, and tended to creep up when stopped or very low RPM.

I pulled the fan and tossed it in a dumpster, and grabbed the 18" "X" blade off a 430 sitting in the corner of my garage.

The car now runs near 190-195, and is quieter (fan noise wise) to boot.

Back to the other stuff.

A fan needs to "fill" the shroud opening as near as can be to touching the shroud, with the "flex" blade I had, two things were happening.

1. The gap was resulting in lack of "pull" of air through the radiator at low speeds, and that is critical to cooling at low speed, or sitting in stop and go traffic.

2. The tips of the fan will create tip vortices and the airflow at the edge of the fan are in a vortice and are not moving any air flow through the radiator. In effect, the gap and the vortice reduce the effective part of the blade to much less than the diameter. SO a 19 in shroud opening and a 16 inch blade adding the "useless" vortice or "recirculating" air at the tips of the blade, and you are now effectively using a 14 inch blade. This is worse at high RPM/Freeway speeds, and with the addition of the blade "flattening" out due to high RPM the blade can actually "block" airflow and with the airflow of many older cars creating a "dam" in front of the grill area, you find yourself overheating on the freeway under load. (Similar to the way a torque converter works, but for different reasons), the air on the ends of the blades are not doing useful work and "rob" the airflow through the radiator.

The best cooling happens when the most airflow through the radiator occurs, without the flow being impeded, or loss of flow because a fan is pulling air from behind the radiator around a large gap between the shroud and the tips of the fan blade.

And the proper sized radiator is critical to match with shroud, and proper fan.

No shroud makes a fan almost useless.

And the last thing in that configuration is the proper spacing of the fan to the radiator. But the shroud/fan fit is a bigger point.

The "odd" paddled fans help with harmonics of vibrating air. Vibration of air and "chopped" with a fan is much the same way a siren works. So, the "odd" paddle blades help break that vibration and harmonic and make for a quieter ride, but still move air.

The old "X" fan blades, as archaic and low tech as they look (and more at home on a tractor that a performance car) are actually pretty darned good at moving air.

Lastly, the clutch fan is great for being "loose" and not adding parasitic loss to an engine, but "tighten up" when needed.

But, they need to be correct for the engine and driving conditions as addressed by others.

Thermostats work by getting and maintaining an engine at the proper "high" temp, not "low". It is closed until the engine reaches the desired "high temp", then opens (and closes) to try and maintain that "high" temp. If the (clutch)fan, radiator, shroud are not properly matched, then the thermostat is unable to do it's job. Some thing the thermostat "keeps" the water in the radiator longer so it can cool properly, or that so the engine can transfer heat correctly, or both, but that is not the function of the thermostat. It lets the engine reach operating temp, then opens to regulate that temp with the goal of maintaining that temp.

(there are a few other things, like pump impellers, and pulleys driving the pump, but this covers a good bit)

Stay cool...

 

Well done.



I'd like to add that while higher temperatures (WITHOUT leading to detonation) are unlikely to cause engine damage, (The dashboard "HOT" light doesn't come on 'til 240+ degrees!) operating temperatures higher than several degrees above the thermostat rating at idle or cruise, leaves little additional capacity for when the engine is really "working"--heavy throttle.

Put another way: If your thermostat has already lost control of engine temperature at idle or cruise, what's going to happen to the temperature when you stab the gas pedal?