4X4 Radiator Fan Diameter? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Beast388 · 04-05-2005, 10:20 AM

I dug out of the garage what I believe to be the factory fan for my '71 Burb and for some reason it looks small. My question is.......what is the diameter of the factory 4X4 fan? Is it an 18" 7 blade version like the one I have?

Thanks for the help.

**JIMs70GMC** · 04-06-2005, 09:19 PM

Mine had a 4 blade 18" fan, actually both had them. No clutch in the fan on either truck.

4x4Poet · 04-11-2005, 03:13 AM

Yeah, 18" but the 7-blade 18" fan is the best. Use it with a factory fan clutch.

BTW, have the fan magnafluxed before you install it. I've recently heard of horror stories of loose used parts fans coming apart due to unnoticed stress cracks. The fact that the fan is not off a running engine makes it potentially suspect. Maybe I'm going overkill. The worst that could happen is a ruptured rad and ruined waterpump bearing.

04-05-2005, 10:20 AM	#1
Beast388 Suburbans RULE! Join Date: Jan 2000 Location: Clinton, IA 52732 Posts: 689	4X4 Radiator Fan Diameter? I dug out of the garage what I believe to be the factory fan for my '71 Burb and for some reason it looks small. My question is.......what is the diameter of the factory 4X4 fan? Is it an 18" 7 blade version like the one I have? Thanks for the help. __________________ --Ben 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, TH350, NP205, 8-lug D44, 14BFF w/ Detroit, 4.10:1 gears, 4-Wheel Disks 4" Lift, 35" MT/R's.

04-06-2005, 09:19 PM	#2
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Mine had a 4 blade 18" fan, actually both had them. No clutch in the fan on either truck. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

04-11-2005, 03:13 AM	#3
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	Yeah, 18" but the 7-blade 18" fan is the best. Use it with a factory fan clutch. BTW, have the fan magnafluxed before you install it. I've recently heard of horror stories of loose used parts fans coming apart due to unnoticed stress cracks. The fact that the fan is not off a running engine makes it potentially suspect. Maybe I'm going overkill. The worst that could happen is a ruptured rad and ruined waterpump bearing. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.



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