Fan Modification for V8 e39 cars

[BarryM]

it really seems to be easiest to just drop in an M5 radiator. They’re all interchangeable, right?

I don't think an M5 rad fits the auto M62 as mine has a heat exchanger for the auto box connecting into it, maybe its fine for manuals but just a thought!

[geargrinder]

If you're puting more heat thru the core you're actually putting MORE load on the fans. Just sayin'.

Juan that's exactly my point about the radiator handling MORE heat. But I was comparing same 88C thermostat, small vs bigger rad cores... not 100+ vs 88 t-stat..

All else being fixed (aka 88C thermostat and same fan setups), if you have small radiator vs better radiator...

The better radiator will presumably require less airflow to achieve the same output coolant temp than the smaller one, therefore, presumably fans will be able to run at lower duty cycles to achieve target temp.

Listen I'm not saying that's a big deal and be a massive difference in fan lifespan... and my car runs great w/ the OE radiator and the 88C and one OEM Aux fan, but, just musing about the theoretical reason the bigger rad could still be a good idea for these 88C setups.

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I don't think an M5 rad fits the auto M62 as mine has a heat exchanger for the auto box connecting into it, maybe its fine for manuals but just a thought!

Nope. It'll drop right in.

Weirdly/ugly-ly BMW decided to plumb the heat exchanger to the drain plug for the radiator. So where you have that H-E hose going to the bottom, manuals have a cute little (blue) plug. Radiators 100% the same. No issue to swap.

[jicaino]

Ah, gotcha JC. My brainfart read of your post was caught on the fly by you, sire.

Yes, better radiator and lower tstat will reduce fan duty, that's true and holds true even for the questioned OE regular core for the 540i. Given a 88°C tstat it's more than enough, to the point you​don't hear the clutch fan anymore"

[bdiefAZ]

Over 500 miles on the M5 since this mod, still enjoying the quieter fan and more airflow. July will be the true test here in AZ.

[computiNATEor]

Over 500 miles on the M5 since this mod, still enjoying the quieter fan and more airflow. July will be the true test here in AZ.

Any updates to this mod? No news is good news?

[adamkas]

Guys, maybe it's bit out of topic but i'm running 88C thermostat in my m62TU engine and one thing is bothering me - factory vicious clutch fan is spinning a lot more time than when i was using OE 105 degrees celsius thermostat. This is probably because when temps which i'm seeing during daily driving are about 93-96C - Tstat is opened the whole time and radiator is sending all the heat into the fan clutch activating it. Reading through this thread i've seen claims that we don't need this piece of garbage (fan clutch) when running 88C Tstat. Is this true? I'm really sick of the fan spooling everytime i've stopped in traffic when the temperature outside is around 30C (86F).
Does ditching the fan clutch require any changes in DME's activation point for aux fan in front of the condenser to run unstressfully?
Swapping to less noisy fan proposed in this post also seems reasonable.
Have a great evening on the other side of the ocean!

[geargrinder]

Think about it. No cooling parts change the amount of heat being created by the engine.

The same amount of heat is always created.

In fact actually by putting a 88C tstat in, you are just shifting more heat to be passed by the radiator, not less. So it’s entirely likely the fan(s) might run more.

Now this is all still good and desirable because the engine parts will be cooler and the bay cooler and system pressure lower and all kinds of good stuff.

But you are putting more calories through the coolant and the rad and therefore sometimes the fan might run a wee more.

[edjack]

I suspect the ring around the blades helps to counter end effects, which decreases efficiency.

[computiNATEor]

I suspect the ring around the blades helps to counter end effects, which decreases efficiency.

The ring doesn't cover the entire blade, and at any rate, the reduced chance of a blade or two exploding through the hood strikes me as a worthwhile tradeoff.

[bdiefAZ]

Fan Update - Summer is cooling down in AZ, the fan mod has held up very well on the M5. I realized this week that my electrical auxiliary fan stopped working. I am not sure when that started, but a replacement is on the way from FCP. I had 3 M5's over recently for fuel injector cleaning / engine de carbon, we were comparing setups on the cars when we noticed that the aux fan was not working! I have been splitting the driving with the truck and M5 all summer, the M5 never ran hot.

[Dking078]

+1 to this, I put in a new E65 fan and clutch. Been going strong for 1500 miles. 0 Complaints, does feel like more air is moving.

[computiNATEor]

Fan Update - Summer is cooling down in AZ, the fan mod has held up very well on the M5. I realized this week that my electrical auxiliary fan stopped working. I am not sure when that started, but a replacement is on the way from FCP. I had 3 M5's over recently for fuel injector cleaning / engine de carbon, we were comparing setups on the cars when we noticed that the aux fan was not working! I have been splitting the driving with the truck and M5 all summer, the M5 never ran hot.

+1 to this, I put in a new E65 fan and clutch. Been going strong for 1500 miles. 0 Complaints, does feel like more air is moving.

Cool, thanks for the feedback. I've put both parts in my wishlist for my M5's upcoming cooling system refresh. I rebuilt the engine but left the original cooling stack intact; I'm on borrowed time with the OE radiator, and I'm looking to drop in a CSF aluminum rad plus new expansion tank. Thankfully, M5s are not known to be cooling-system failure prone.

[rlordjr]

Very interesting thread and when the WP/thermo need replacing maybe I'll use the 88 option. Have any of you tried NPG coolant (Evans)? It makes the pressure issues go away completely although in my experience engine runs about 1-2 CEL warmer. I'm thinking that small heat difference is not important when compared to having very low (almost no) pressure in the cooling system. Thoughts?

[baneoh]

This is an interesting mod but maybe I'm missing the point? Why would one choose to do this rather than convert to an electric fan?

[rlordjr]

I'm also wondering about why not just switch to an electric fan? BTW I have gone back to regular coolant and water from the Evans NPG. Had to replace leaky radiator and its super hard to keep the NPG from absorbing water (ye gads, it HYGROSCOPIC). Would need to replace with new and that's $200. $40 worth of BMW coolant and $5 of distilled water with coolant left over is all good. Now engine runs at 90ish. Maybe too cool? It has been in the 20's and 30's American degrees so I'll see what warmer weather does.

[CPHES]

I’m not an electric fan proponent. Too many years of VW/Audi/SAAB where electric was the only way. As long as the engine is running, the mechanical fans turn. I have a v12 and a v8, so there’s not much impact to the overhead of the clutch fans.

[f355spider]

Is there an data that proves this fan mod actual moves more air (CFM) than the original fan on an M62 engine?

BTW, there are tuner shops that can change the cooling maps to open the oem thermostat sooner on an M62 engine. I was at DUDMD Tuning last fall and they did that on my car, as well as raised the idle speed 100 rpm. Not sure the details on all the "hows and whys" of these changes, but they said the engine would run a bit cooler and idle smoother.

[computiNATEor]

This is an interesting mod but maybe I'm missing the point? Why would one choose to do this rather than convert to an electric fan?

I'm also wondering about why not just switch to an electric fan? BTW I have gone back to regular coolant and water from the Evans NPG. Had to replace leaky radiator and its super hard to keep the NPG from absorbing water (ye gads, it HYGROSCOPIC). Would need to replace with new and that's $200. $40 worth of BMW coolant and $5 of distilled water with coolant left over is all good. Now engine runs at 90ish. Maybe too cool? It has been in the 20's and 30's American degrees so I'll see what warmer weather does.

This is way easier than adding an electric fan. To add an electric fan properly, you're talking relays or PWM controllers, plus wiring and mounting in a non-OEM way.

The OEM manufacturers generally really know what they are doing. They're not stupid. Especially suppliers.

[CPHES]

This is the e38 thread - https://www.bimmerforums.com/forum/s...-clutch-in-E38

[jicaino]

Think about it. No cooling parts change the amount of heat being created by the engine.

The same amount of heat is always created.

In fact actually by putting a 88C tstat in, you are just shifting more heat to be passed by the radiator, not less. So it’s entirely likely the fan(s) might run more.

Now this is all still good and desirable because the engine parts will be cooler and the bay cooler and system pressure lower and all kinds of good stuff.

But you are putting more calories through the coolant and the rad and therefore sometimes the fan might run a wee more.

I had to read the first 3 sentences a couple of times to understand it.
Yes, at the same given load and engine speed the amount of heat will be the same.
Changing the tstat does not changes the amount of heat passed by the radiator, since the factory setup does the same when the DME knows the engine will need the additional cooling. It prevents the unnecesary heat build up cooking the engine bay when the engine's being driven al light loads and rotational speeds.
In my experience since I started using the 88ºC thermostat, the fan clutch (which I reinstalled only because the A/C in low speed traffic was causing the aux fan to be more annoying than the "wooosh" of the clutch fan) is barely noticeable. The regular 540i blades, not the improved, quieter X5 one.
Under the hood the things have improved considerably, and the latent heat transfer to the cabin has been significatnly reduced. I don't think I've ever heard the aux fan again (at least not running faster than just a "renforcement" of airflow at low speeds-high ambient temp, and yes, it does works, I tested it out of concern it wasn't working) and the clutch fan stayed on because it wasn't an annoyance anymore. I've tried it with no clutch fan and it seemed perfect too, without readjusting the PWM trigger points for the aux fan.

Bottomline: use the 88ºC. You will regret you didn't do it sooner.

[vien]

damn i should post my electric fan upgrade.

[BarryM]

Thanks to the OP for this idea, just installed an E53 fan & viscous coupling in my M62 B10, will see if it has any impact when the weather warms up in a few months but if it only runs a bit quieter I’ll be happy.

Not interested in the effort and complexity of an electric fan.


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[computiNATEor]

Not interested in the effort and complexity of an electric fan.

100% agree.

[nsticka]

+1 to this, I put in a new E65 fan and clutch. Been going strong for 1500 miles. 0 Complaints, does feel like more air is moving.

P/N?

question for everyone else: whats the difference between M5 radiator and regular M54 radiator? capacity? end tanks?

would you need to use the aux fan from M5 as well? anyone upgrade their aux fan or is genuine BMW aux fan enough?

[CPHES]

See the first post in this thread.....

From that post

I have swapped out 3 fan blade/fan Clutch Assemblies recently with this modification:
· e39 with M62Tu engine
· e39 with S62 engine
· e31 with M70 engine

The fan comes from the E65, E66, and E67 7 Series, as well as the E53 X5 with V8 and mechanical fan:

Parts needed for the mod:
Fan Blade 17417504732
Fan Clutch 17417505109