[RandyW]

The old clutch fan is 19" also, fits with a ton of room to spare.

[HWYSTR455]

In the daily driver I have, I've always run a clutch fan. I'd say in like 1999, the clutch I had started leaking and wobbling, and chose to replace it. I went through every clutch that was on the shelf at two different parts store, and all ran hot. I know it was directly related to the clutch, since when I put the leaking, wobbling unit back on, it dropped that 10-15 degrees it lost with the new clutches.

To correct this I ended up choosing a clutch that was non-thermal, for a GMC truck I believe the application. Maybe something with the thermal springs is the issue?

The flex fans are good, and if you choose the right one work well at keeping temps down. If. Belt slip, noise, and power loss tend to be an issue with flex fans, and can be just as frustrating to find the 'right' one as finding a clutch.

[Z Code 400]

So far, the severe-duty thermo clutch is keeping temperatures right at 180°F. I will keep testing it for a while to see how it holds up...Robert

[RandyW]

I'll probably go back to a clutch unit now that I know the problem is solved at the fan. I'll find a good unit and put the stock fan blade back on. Or I'll scrap it all for electric! LOL

[71firebird400]

Put a new clutch on it today (Hayden HD) and the fan pulls a LOT more air.

But, now its back to squeeling! Ahh!

Any ideas on how to prevent the annoying squeeks? It did not happen with the "worn out" clutch, only when there's a lot of load on the water pump pulley (due to the new clutch pulling a lot more air).

My theory is that the increased load of the fan pulling so much more air is causing the belts to lose traction on the pulley. So do I need different belts?

[71firebird400]

Well I tightened the alternator belt further than I thought safe and it's the only way the noise goes away. We'll see what happens?

As for the fan, the new clutch looks like it's keeping the motor at 180 so that's good news. So far, so good.

Thanks everyone

[71firebird400]

Update;

After running the car some more it appears that this fan clicks on around 210 and brings the car down to 180, then clicks off. This is a little hot for my liking, is there any way to get it to turn at 200 and bring it down to 170?

Suggestions?

[Z Code 400]

Mark,

That's how the clutch works.....it applies around 200°-210° and then disengages around 170°F. This is confirmed by the operating description I have in sveral GM manuals. However, after driving my car the first day, (about 100 miles) the temperature stopped going to 210°F and the fan started coming on around 185°/190°F and then disengaging around 170°F or so. I cannot explain it, but that's how it is now working. I can leave the car idling in direct sunlight (95°F ambient) for a half hour and it won't go over 185°F. I can hear the fan engage and disengage at idle speed.

Belts....

Use a good quality belt. The only ones we could get to stay on the pulleys with solid fans turning 8000+rpm (oval track applications) were the Dayco Diesel Engine Grade Belts. I have the 'big' non A/C water pump pulley, so I am turning the fan slower than it would run on an A/C car.

Hope this helps...Robert

[Z Code 400]

Mark,

Dayco is now marketing these belts under the tradename Dayco® Top Cog® Gold Label® Belts...Robert

[70GS455]

is there any way to get it to turn at 200 and bring it down to 170?

I wonder if you could "adjust" (i.e. bend) the thermal coil spring on the front to get it to engage at a lower temp.

[70GS455]

Hmm. I found this to be interesting. This is from Hayden's FAQ section on their website:

Q. At what temperatures do fan clutches engage?
A. Most fan clutches engage at about 170° F air temperature (about 180-190° F engine temperature). They reduce the temperature about 20° F before disengaging.

Q. I have a late model Chevrolet or GMC truck. The original equipment fan clutch does not engage until the engine is past 210° F. Does Hayden make a fan clutch that will keep the engine cooler?
A. Yes, our fan clutches for these vehicles are specifically designed to engage at lower temperatures than the original equipment fan clutches that they replace.

I think they consider "truck" and "severe-duty" to mean the same thing. Not sure how much cooler these engage at.

[Tempest]

Remember, the heat to activate the clutch fan comes from the rad, and if your fan is 3-4 inches from the rad, the heat is dissipating before it reaches the spring on the clutch. I just removed my 7 blade clutch fan that was running at 210, and replaced it with the original 6 blade fan from my 326 Tempest. I am now running at 180, and today was stinking hot with high humidity. Clutch fan looked good, but it does pull air like a regular fan.

[Z Code 400]

I just installed a Torq-Flo Severe-Duty Fan Clutch and 18.5" 7-Blade Fixed-Pitch Fan from an air-conditioned 1981 Monte Carlo. The clutch part number is 922799 and the application is 1984 GMC Suburban, 2500 4-Wheel Drive, with 6.2 Litre Diesel and 3.73:1 and numerically higher axle ratios. This clutch has a 3/4" pilot and I use a custom made bronze bushing to adapt the 6.2 litre's 3/4" pilot to the Pontiac's 5/8" pilot. It is designed to operate at higher engine rpm.

Alternatively, you can order the 922747 clutch, which has a 5/8" pilot. It is for the 350 CID Suburban.

So far, my car stays on 170°F to 185°F all the time, even in 100°F heat. I am still testing this unit, but so far, it's working great...Robert

[71firebird400]

Well with this fan, it lets my car get up to 210 while I'm driving, then it turns on but by that point it seems like it just isn't pulling enough air to drop it back down.

I really wish this thing would get it down around 170-190 while I'm driving instead of 190-215. I think I may put the flex fan back on or start looking at the electric stuff.

[Z Code 400]

71400,

What brand are you using??? The Torq-Flo Severe Duty I bought keeps mine at 170°F to 185°F all the time...even if I let it idle for 30 minutes in 100°F ambient temperatures.

My e-mail is on my PY Profile. Contact me and I will share some tips with you...Robert

[71firebird400]

Thanks Robert, sent you an e-mail.

[Z Code 400]

Reply sent....Robert

[Z Code 400]

So far, this new clutch is working well. Temps stay at 180°F to 185°F all the time, regardless of outside temperatures or road speeds. However, this is still hotter than the car ran with the Lincoln 7-Blade Flex Fan.

When I was running that fan, you could watch the temperature gauge drop when you drove past orchards when they were irrigating. With the clutch fan, the needle stays in the same place all the time. With the Lincoln 7-Blade Flex Fan, you could actually watch the temps drop all the way to 160°F while driving on the freeway at high speeds.

Time will tell...Robert

[70GS455]

Here is a response I got form Hayden re: engagement temps:
--------------------------------------------------------
Thank you for your inquiry. Most early GMs cars did not use heavy or severe duty fan clutches. The lighter blades on these cars will not slow down the heavier fan clutches and they will spin full speed all of the time.

To get a SD or HD clutch to function they require a fan with about 2-1/2” of pitch. Typically that type fan is used on GM trucks up to 1988.

Most SD and HD fan clutches engage at the same air temperature of 180 degrees. If you are able to locate a fan with deep pitch you can use SD fan clutch 2797.

Bruce Stone

Hayden Automotive

Product Analyst

[Z Code 400]

70GS455,

Great information....

My fan is from a 1981 Monte Carlo and it is identical to the 7 blade fan I removed from a 1974 GMC Truck with a 454. In contrast, my 1985 Suburban came from the factory with the common 19" 5-Blade Fan you see on most later GM vehicles.

Bruce Stone might be onto something...When my fan engages, it creates a turbulance that can be flet in the fan shorud, but not on the engine. It is clearly 'buffeting' and not a mechanical vibration. The airflow noise is very pronounced and you can feel air being pulled through the grille 4 feet away.

Not only will my SD #922799 (Autozone) clutch engage and disengage at idle speeds, you can actually hear it change speeds while engaged. The car sounds just like it has an electric fan on it...Robert