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Discussion Starter #1
TLDR: tried the E65 fan and clutch in my E38 750iL, it ended up being a struggle and we will see if it was worth it for me (M73N) but it could be easier for an M62/62TU.

We all know the fan and viscous clutch combination in our vehicles are liable to seize, explode, and let loose an avalanche of destruction. It has been proposed that the E65 fan and clutch are a direct swap and provide better reliability and less chance of catastrophic failure. I decided to see if it was true.

Testee: 2001 750iL, M73N
Parts needed:
  • 17417504732 Fan QTY 1
  • 07119904125 Hexagon screw w/ coupling QTY 4
  • 17417505109 Fan coupling QTY 1
Reaoloem: http://www.realoem.com/bmw/enUS/sho..._2000_E65_BMW_735i&diagId=17_0224#17417505109

The parts are nice compared to ours. The fan is supposed to move more air and with the ring give more stability (less chance of explosions).

The viscous clutch is beefier and slightly taller. That is okay as the fan mounts on the back vice the front.


The clutch also fits nicely in the correct location.

Combined they are nearly the same size

That being said there are some differences that make it a pain with the M73N.
The first is (and the astute will have seen it in the parts list) are the 4 hex screws that (I assume) are slightly shorter than ours. A washer under ours and golden.

Not sure, long term, I want to rely on that but for testing purposes it should be fine.

The second: With the ring the fan won’t go into the area without pulling the shroud up and into weird positions. The original (sans ring) allows just enough wiggle room that you can slide it out without removing anything else. Not so with the ring. Although draining the coolant and completely pulling it would work, I don’t want to go there every time. So wiggled and worked it and it does fit.


Now I will need to see if there are any differences in operation. Will give it a few days and report back.


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1
 

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Discussion Starter #2
First shake down completed.
Being “smart” I started with the hood up to judge the various wind generated.
Holy mother of god...
It fired up and whooshed like they all do but this was something more. Massive air going through. It was normally a strong breeze with the old fan (you know the breeze when you are checking for something under the hood with the engine running). This one gives a stiff wind. If I had to guess about halfway between the old fans engaged and not.
Closing the hood and I could feel the air being sucked through the grills. Normally you can feel something but this was like having your hand out the window at 25.
As most of us do, I have a “shake down circuit” of about 10 miles. Mine consists of right turns, hills, twistys, and varying speeds of 25-55 mph. I’ve done it enough times that I know where the temps should be.
I ran it twice and never got above 104. Cruising was 102; normally 104.
Thinking “well it is below freezing “ I decided to run it backwards. This gives left turns and long waits at lights. There is one light that normally has me waiting for a bit. Temps get to 107 then the hill at 45 is enough of a load the thermostat opens and temps plummet to 90s.
At the light it never got above 105.
On the hill, the tstat never opened and I held at 102.
Overall the mpg on the circuits was normal: 18.3.
There are several things that could account for this but as this was the only thing I did to the engine today...
Now for the draw back because there always is....
Hard to say with certainty but I felt the engine was working a little harder, maybe 100 rpm? Where I would normally cruise at 1500 rpm I felt like I was doing 1600, 2200 was 2300; idle at 750 was 750 though.
So there are probably some lost ponies.
But overall definite increase in air flow and I am not racing I can live with it.
More to come after standard commutes etc.


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1
 

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Re: Nice thread and way to challenge the norm!

Hey TheAngryBear:
1st, not quite sure to read into your "handle" aka: Bimmerfest User name...lol!!
Nice thread and congrats on thinking outside the box and not being afraid to DIY and trial & error!! I hope it keeps on working for as long as you own the Bimmer..;-)
 

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Discussion Starter #4
The handle came from the 540 being compared to a 530 in the PO timeframe. 530 is quick and nimble like a rabbit, the 540 can charge and move like an angry bear. I took that name for the vehicle and handle then lost the vehicle...

Thanks and feedback as it is used (to come, locked down to snow/ice now)


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1
 

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Discussion Starter #5
So it has been almost a month and figured a report back is due.
Overall I like it very much and recommend it.
The initial additional rpm seems to have gone and it is the same as ever. I suspect I was just hypersensitive at the initial install.
Temps have taken longer to reach full operation and stay slightly cooler. On my standard commute I would reach 102 to the gated entrance. Now I am regularly at 98. Movement at operating temps used to be 104 now is 102. Over 40mph same as ever of about 102-104. I have yet to go above 106 but maybe in the hot summer (we had a few 70°F days).
Air movement is still the same (lots) with the largest difference being noise. The old fan sounded rather loud at cold start, this one is louder at cold start but nowhere near the same level. I have to actively listen for it to hear it.
The washers and 2 bolts are holding up as well...
More as it develops and I remember to update.


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1
 

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Can you keep the m62tu fan clutch and just use that fan instead? Will it bolt up possible? Can you test fit that?


Sent from my iPhone using Bimmerfest
 

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Discussion Starter #7
Can you keep the m62tu fan clutch and just use that fan instead? Will it bolt up possible? Can you test fit that?


Sent from my iPhone using Bimmerfest


I don’t think so. Third picture in original post shows the mounting diameter differences. Also the mounting side is different so the offset would be wrong. You might be able to make it work but not using the intended mounting holes...


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1
 

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Discussion Starter #9
Can you be the guinea pig for us?


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Ha! I am happy with the setup as is. However, next time I have the fan off (and I remember) I will take a few pics to show possible consideration for you. Deal?


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1
 

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Considering this for the M62 with the summer coming on. No issues presently but I like the ring surround and the beefier clutch.
And as we all know, 'presently' don't mean squat when it comes to the E38... labors of love.
 
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