Radiator Fan Clutch

Ford radiator cooling fan clutches are identified by basic part number 8A616. Fan clutches are used on fixed-pitch fans to control fan spin based on temperature and engine RPMs. The clutches contain a viscous silicon-based oil which gets pumped in and out of an internal drive area depending on engine RPMs. A bi-metallic spring/switch operates a control valve that regulates the amount of oil flowing within the pump. Here's a table describing fan clutch applications and engineering numbers:

ApplicationService Part NumberEngineering Part Number
1970 before 1 September 1969C9ZZ-8A616-AC9ZE-B
1970 from 1 September 1969D0ZZ-8A616-AD0ZE-A

Here are front and back pictures of the C8OE-B and C8OE-C fan clutches (images courtesy of Jack Wofford):

C8OE-B and C8OE-C Fan Clutches, Front

C8OE-B and C8OE-C Fan Clutches, Back

Here are front and back pictures of a restored C9ZE-B fan clutch (note the engineering number on the mounting flange):

C9ZE-B Fan ClutchC9ZE-B Fan Clutch Detail
C9ZE-B Fan ClutchC9ZE-B Engineering Number Detail

The 1970 D0ZE-A clutch isn't very common and is very hard to find today. Here's a series of pictures of one that recently surfaced in New Old Stock condition, including a comparison to a C9ZE-B clutch:

D0ZE-A Fan ClutchD0ZE-A Fan Clutch
D0ZE-A Fan ClutchD0ZE-A Engineering Number Detail

D0ZE-A and C9ZE-B Fan Clutches

D0ZE-A and C9ZE-B Fan Clutches

Bill Upham of Mansfield Restoration Parts was kind enough to share the pictures of the D0ZE-A clutch shown here. He compared the C9ZE-B and D0ZE-A clutches side-by-side and has this to say about the differences:

"After viewing the 2 together the only thing I noticed was that the thermal spring is installed in the opposite direction when compared to the C9ZE-B shown, but I do not think that it makes a difference. I believe the difference between the C9ZE-B and the DOZE-A is in the calibration of the thermal part for whatever reason."

Loss of fluid and subsequent bearing damage is a frequent problem with these fan clutches as they age. Fortunately they can be professionally restored by a company named Pampered Corvettes; contact the company directly for details. If you're looking for a replacement clutch and don't care about originality, Matt Kunkle reports that the Motorcraft replacement clutch for a 1971 Lincoln 460 (part number C8SZ-8A616-B, which may or may not be available from your local Ford dealer as of this writing) will fit and work just fine. Unfortunately, I've also heard that this clutch doesn't fit.

Notice the ink stamp (18IC, 123J above; A27J below) that's visible on some of the clutch pictures shown here. I'm not sure how to decode it, though at least part of the stamp appears to follow Ford's date code format.

A27J Stamp

Image courtesy of Brandon Badell.

I have received reports that say that certain aftermarket clutches made by Hayden (catalog available on their web site) will fit. Part number 2765 (1.09" shaft, 3.25" bolt circle diameter, 7.20" diameter clutch body, 2.67" overall height) is supposed to fit with the C9ZE-E fan. This clutch is available from NAPA under part number TEM 261306. Part number 2711 (1.40" shaft, 3.00" bolt circle diameter, 7.20" diameter clutch body, 2.98" overall height) is supposed to fit with the C8OE-B fan. This clutch is available from NAPA under part number TEM 273370.

Here are two pictures (picture 1, picture 2), courtesy of Jim Woods, that show the 2765 clutch compared to the C9ZE-B clutch.

The funny thing is that the Hayden catalog says the correct replacement for a 428 CJ is part number 2710, but in looking at the description in the catalog it's clear that the 2710 will not fit. The bolt circle diameter and height are both wrong. Hmm...