72 Radiator replacement... Any land mines?

Now is the time to install a 1981 320i temperature sender in your new radiator with a relay to actuate your auxiliary fan.

https://www.rmeuropean.com/Products/6131136427282-MFG85-V42.aspx

Every car BMW has made starting with the 1974 e9 coupe has had a auxiliary fan mode for engine temp control.
Most cars had low and high speed fan modes.

If you don't have the black box on your fender with a wire going to the temp sender in the thermostat housing-
now is your chance to buy some protection for cheap...

If you have AC you will need a BMW diode, a relay, a fuse holder, the sender and a relay base.
Instant protection from hot days sitting in traffic.
 
@sfdon can you list what auxiliary fan you use? As I recall it’s a Spal fan but I can’t remember if you tend to use a single fan or their smaller two-fan setup. And I assume this mounts on the front of the radiator as a push fan through the radiator to supplement the standard fan behind the radiator? I don’t have AC but adding the aux fan is pretty easy, have done it on two other cars so should follow your lead here
 
The Spal pusher fan fits well and pushes almost 2000 cubic feet per minute.

Always buy the curved blade version .... straight blades are really really noisy.
 
remember, the automatic uses a different radiator than the manual tranny coupe. there is an oil cooler in it. if you happen to need one to be recored, i have a working one that is no longer in my car. yours for shipping / small donation to e9coupe.com ($50)
 
D Calkins said:
Can you please share the gen 4 part numbers? What do you want for your gen 3 set up?
Click to expand...

See this thread wherein @sfdon lists off the parts
Boobouna

Thread 'Viscous fan coupling aka Viscosity fan clutch'

Hi all,

My 1975 BMW 3.0Si has a viscous fan coupling which has failed. My car is still running the original 5 blade red fan setup. From what i can see this part is NLA and the replacement option is linked to the 9 blade fan setup. Is this correct, see below? Is this my only option? Does anyone have an NOS of the original? Will the below setup fit without any issues or is it a tight fit?

1742378493564.png

Regarding the gen 3, I got this from another forum member, here are the pictures for the items with part numbers shown. I no longer have the shroud, another member bought it, but the shroud appears to still be available. Reach out via DM, thinking about $100 plus shipping would be fine.
Note that you'll also need to change the pulley. I don't remember what the part number would be for the gen 3 version or whether it's the same as the gen 4.
 

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And since @D Calkins is new and I distinctly remember this confusion, the way to identify all of these is
Gen 1 has red 5-blade fan and no shroud
Not sure about gen 2 but I think it's just 9-blade fan upgrade?
Gen 3 is pictured above and has 9-blade fan with upgraded viscous clutch and a separate shroud
Gen 4 as Don mentions in that thread has a fan with an integrated shroud, also with an upgraded viscous clutch (different from gen 3). Advantage is the integrated shroud and the thinner fan in a relatively tight area.

The challenge for me for the gen 4 did end up being the pulleys because the one needed for the gen 4 is somewhat hard to find and unfortunately often expensive. I know Don is able to find them, it seems like all old BMWs go to California to be scavenged by rebuilders there. All I get here in Washington are rusted-out cars in fields.
 
Just use the original water pump, the first gen viscous clutch called a ‘bolt on’ as it uses the center mount with the bolt on the forward side and existing pulley. See diagram in Post 26. The second gen clutch is a ‘spin on’ with the large 32mm nut on the rear of the clutch and requires a newer water pump and pulley. Don knows that I think the fan with the outer ring just does not look correct. Use a shroud if you want, they were introduced on 74 coupes.
 
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