1957 Buick Roadmaster clutch fan

[nailhead9]

I need a new rebuilt clutch fan for my 1957 Buick Roadmaster. Ever since I replaced the water pump last summer I have noticed that when idling or in parades the coolant temperature is higher than it was with the old water pump. I had this checked out at my local garage and they told me the fan was turning at a lower rate (rpm) than the engine. They also said that I needed a new or rebuilt clutch fan. Does anybody know about this, or know if or who rebuilds clutch fans. A NOS clutch fan would be great.

Thank you in advance for your help,

Warren

[NTX5467]

I suspect your existing clutch does not have a thermostatic device on the front of it as the later coil spring thermostatic controlled clutches appeared along about 1963.

"Universal" non-thermostatic controlled fan clutches are available. Just have to match the center pilot hole's diameter and depth with what you have PLUS the shaft length and such. These were rpm-limited clutches which cut-out at a pre-determined rpm (usually at "road speed") rather than temperature controlled (as the later ones were with the coil spring on the front.

In reality, though, if you can find a clutch that matches your fan's bolt diameter, the correct fan mounting pad to the end of the mounting shaft length, the correct center pilot hole diameter (and depth), whether the earlier style or the later thermostatic style, it'll probably work.

Fan speed does NOT have to match engine rpm. The basic rpm of the water pump (and fan) is determined by the pulley sizes (relationship between the crank pulley and the water pump pulley) . . . which is "a vehicle design situation" that is not recommended to change UNLESS you know what you're doing.

What IS important is the pitch and number of the blades. Most fan clutch engines used fans with about 7 blades.

NOW . . . here's a side issue which happened to me . . .

We've all suspected that "bigger is better", so when I needed a water pump for my '77 Camaro V-8, I opted for an aftermarket (name brand!) water pump rather than an OEM pump. One factor was price. When I got the new pump, I looked at it and saw larger and cleaner internal passages, which I perceived to be "good", considering that many people talked about "high flow" being better to keep things cool. I put in a new thermostat, too, with new coolant.

When it was all done, I noticed that the temp gauge needle was one-needle-width higher when the engine was fully warmed up. How could this be??? More flow, better this and that??? But it was running hotter??? According to the "gurus", it should have been just the opposite!

When that one started leaking, due to accumulated mileage, I got a reman pump (from a reputable rebuilder!) BUT in a factory casting rather than the aftermarket casting. With the original factory casting, there was one bolt that had enough clearance that I could use a deep socket to get to it, but on the aftermarket casting, I had to use a wrench. So, getting back to the factory casting had it's benefits . . . PLUS the coolant gauge registered back where it used to with the earlier factory casting pump.

I suspect THIS might be the issue rather than the fan clutch, due to my prior experiences.

In the world of Mopar, the preferred water pump drop-in is the a/c pump with its fewer vanes on the impeller. BUT the pulley ratio on the a/c cars is such that the water pump turns higher rpms than on a non-a/c car, which means the fewer impellers, turning faster, still move the same amount of water as the 8-vane non-a/c pump does at lower rpms.

In a cooling system, the VELOCITY and VOLUME of the water as it passes through the engine is what becomes "cooling efficiency". If the water moves too fast, not enough heat is transferred to the coolant, plus the possibility of air bubbles increases. If the water moves too slow, the radiator can be overpowered, especially if it might be in possibly marginal condition as a heat exchanger. Still, though, the thermostat is a key item in that it restricts coolant flow, as an additional flow regulation device.

You can test the fan clutch by, with the engine OFF, grasping a blade and checking the resistance as you try to gently turn it. If there's resistance, it's probably still good. If you can spin it, might be time for another one.

["shadetree fix" -- with the fan clutch off of the engine, lay it shaft down on two sturdy wood blocks . . . with a blunt Phillips screwdriver and a hammer/mallet, gently indent the front of the fan clutch, once on each side of the center. What this does is increase the fluid pressure in the reservoir of the silicone fluid inside of the clutch, which is the "drive fluid" of the clutch . . . think "fluid coupling". I did this on one of my cars and it pretty much locked-up the clutch so it ran the fan all of the time. A dealership tech keyed me in on this, except he "center-punched" his two "dimples" all the way through to lock-up the clutch. Later on, though, when I had funding, I got a new Dana thermostatic clutch for the car. Proceed at your own risk!]

In order to address any "heat" concerns, you might get an infrared non-contact thermometer "gun". Harbor Freight or Northern Tool are good sources . . . might even be on sale. Then, with the engine at operating temperature, you can check the water temp at the thermostat housing and correlate that to what the gauge indicates. You can also check the temps of the various areas of the radiator, too, to check for possible "non-optimal" internal areas. I recall some other posters commenting that the factory gauges were not all they should have been, back then, or as they've aged over the years. Check Harbor Freight as I think they have some of the IR themometers on sale now. Handy little devices!

Just some thoughts,

NTX5467

[Guest Jim_Edwards]

I need a new rebuilt clutch fan for my 1957 Buick Roadmaster. Ever since I replaced the water pump last summer I have noticed that when idling or in parades the coolant temperature is higher than it was with the old water pump. I had this checked out at my local garage and they told me the fan was turning at a lower rate (rpm) than the engine. They also said that I needed a new or rebuilt clutch fan. Does anybody know about this, or know if or who rebuilds clutch fans. A NOS clutch fan would be great.

Thank you in advance for your help,

Warren

Several things come to mind here. The first being the "new" water pump may not be producing the same flow rate as the old one, i.e.; may have slightly different impellers than the original. Secondly, if the old belts were used they may be worn sufficiently to have altered the pump rpms. Then there is the matter of the thermostat needing to be replaced, they can and do gradually loose function. Radiator condition and coolant mixture may also be a factor as well as the coolant temperature sensor.

In the 1950s four blade fans were the norm on virtually all cars not having A/C and in city driving they have typically proven to be inadequate with today's traffic situations. I'd scrounge up a six blade fan from something regardless of replacing the fan clutch. Now to the fan clutch itself. Easiest way to get a new one that has sufficient clearance is to take the old one to a parts store and do comparisons until one is found with the same distance between the flange and the fan body. As long as the shaft diameter and bolt pattern is the same it really doesn't make any difference what a given fan clutch may be listed for in a catalog.

Don't know if you get into judging and I certainly don't know if that sort of modification would cost points because I don't get into that sort of thing. But even if a six blade fan is a points off modification, loosing a few points is far better than cracking heads.

Edited February 1, 2012 by Jim_Edwards (see edit history)

[nailhead9]

Thank you both for your help. My Buick has factory AC. The fan is correct. I feel the is problem is the clutch fan. When the engine is up to normal operating temperature, or even higher and is turned off, the fan keeps on turning. This is why I believe it is the clutch fan not working.

Jim, I agree with you. I am not into and do not do a lot of car shows. When I do go it is to look at the other cars. I do not care about judging, I do like to keep my vehicles as original as possible, however I am more concerned with driving and will made improvements that help make the car a better driver.

Thanks again for your help, Warren

[NTX5467]

Check the BCA Post-War forum for posts by "Old-Tank" on which fans work to upgrade later 1950s Buicks. In his case, 1955, which I suspect is similar. He might also have some information on fan clutches, too.

If you find one of his posts, you can PM him, too.

Enjoy!

NTX5467