Fan Modification for V8 e39 cars

[geargrinder]

I don't think I agree. In the E46 non-M world, the cars that came with the electric fan typically get a good bit more life out of the water pumps.

OK OK I'll stand down. For now. ;^)

I just have always had WP fail either from seals, or, from non-metal ones, from impeller implosion, long before any bearing related issue becomes a problem....

[jicaino]

OK OK I'll stand down. For now. ;^)

I just have always had WP fail either from seals, or, from non-metal ones, from impeller implosion, long before any bearing related issue becomes a problem....

I don't think I've ever seen a WP fail because of the extra load the viscofan puts on the shaft.

[Uturn540]

I am also curious about the fan mod. Just did a two day 750 mile turn around to west Texas. I noticed that my running temp was 102C and would intermittently bump 103 up hills and 99 down hills. That is with the 88C thermostat and no viscous fan. Outside temps varied between 21F and 55F. Of course if the AC is turned on it drops to 93 to 95C and stays there. I am more interested in the mod for summertime travel if the electric fan decides to take a dump in the middle of nowhere which is where I was most of the time.

[MotorMouth93]

You shouldn’t be seeing temps that high with an 88C thermostat....mine sits at 90-93C pretty much all the time. I don’t have a viscous fan either.

[Uturn540]

I was running without the AC or defroster on. With the AC on it will stay in the mid 90's even in summertime Austin stop and go traffic. It may be the coding not turning on the electric fan until it gets hotter.

[MotorMouth93]

Once you get above 25mph or so fans are meaningless. If you’re seeing 100C while driving over 25mph you have a problem.

[geargrinder]

Once you get above 25mph or so fans are meaningless. If you’re seeing 100C while driving over 25mph you have a problem.

Beat me to it and totally agreed. Something not right. Bad fan or bad radiator or bad temp sensor or something.

[computiNATEor]

Beat me to it and totally agreed. Something not right. Bad fan or bad radiator or bad temp sensor or something.

... Or you're working the engine and cooling system extremely hard at 30-40 mph. I saw my M5's temps climb from 80ºC to 96ºC (and oil temps climb to 125ºC) while charging hard up a steep, twisty road. 35->55->35->55 (with little braking because of the incline) on a 7+% grade at mid 70s temps = hot engine, even with a well functioning auxiliary fan and mechanical fan.

[Uturn540]

With the AC on the temps are good so the fan is not the issue and both sides of the sensor read one degree difference. Planning on a cooling system service this summer. It may be time to replace the radiator since it is coming up on 14 years, in the meantime I will pull it into the shop and blow out the exterior of the core. Road speed averaged about 78mph, also had a tail a quartering tail wind most of the way.

[geargrinder]

99 down hills. .... Outside temps varied between 21F and 55F.

These are the telltales that something is wrong with this scenario. At those ambient temps at 78mph and an 88C, there's no way you should be 99C going downhill.

Of course if the AC is turned on it drops to 93 to 95C and stays there.

This may tell us something. Either radiator is clogged and needs extra fan to keep up, or the airflow is clogged somehow, or something else is going on. Maybe fan is failing so it doesn't operate well at low duty cycles and has to hit say 60% before it kicks in?

[Mannyf540]

Who made those $$$$ water pumps for the i6 engines that everybody was praising?
I've read more than a few posts about the bearing crapping out in them too.

Stewart did Jim

[TerraPhantm]

Beat me to it and totally agreed. Something not right. Bad fan or bad radiator or bad temp sensor or something.

That was my thought. But on the other hand there must be a reason the DMEs keep the electric fans going until 140km/h or so

[jicaino]

These are the telltales that something is wrong with this scenario. At those ambient temps at 78mph and an 88C, there's no way you should be 99C going downhill.



This may tell us something. Either radiator is clogged and needs extra fan to keep up, or the airflow is clogged somehow, or something else is going on. Maybe fan is failing so it doesn't operate well at low duty cycles and has to hit say 60% before it kicks in?

This. I'd start by removing the front end and see if the rad isn't clogged with road debris

[Uturn540]

This. I'd start by removing the front end and see if the rad isn't clogged with road debris

Already ahead of you. Radiator was replaced in 10-2005 and has not been out since. You think this is the culprit? Almost embarrassing20190126_111916.jpg.

[JimLev]

^_anything living down in there?

[Uturn540]

^_anything living down in there?

No, but there was some tumbleweed from when I lived in NM.

[jicaino]

Already ahead of you. Radiator was replaced in 10-2005 and has not been out since. You think this is the culprit? Almost embarrassing.
20190126_111916.jpg

Holy sh*t yessir that's most likely the cause. It's about 50% restricted. Furthermore that looks like clayish dirt caked into the fins, which is worse than just dead bugs and debris.
I'd estimate your system's operating at around 50% efficiency. Ask me how I know. BTW clean also the PS/Autobox and AC cores in front of the radiator
IMAG0706.jpg

[bdiefAZ]

Fan Mod update:

Mileage driven on e31: 25
Mileage driven on e39 M62Tu: 575
Mileage driven on e39 M5: 100

So far, mod working well, fans are quiet and changes the sound of the engine in the cabin. I know that this is not a lot of mileage, the best update will come in July from here in Arizona! Will keep you posted.

[BarryM]

Fan Mod update:

Mileage driven on e31: 25
Mileage driven on e39 M62Tu: 575
Mileage driven on e39 M5: 100

So far, mod working well, fans are quiet and changes the sound of the engine in the cabin. I know that this is not a lot of mileage, the best update will come in July from here in Arizona! Will keep you posted.

Ahh........back to the reason for this thread

I'm very keen on this mod but the fan and coupling work out ot £230 over here in the UK so that's a bit of a downer but anything that will keep the cooling system running more efficiently is a good move in my book. The Alpina 4.6 is fitted with the BMW tropical radiator for the M62 which I believe has a bit more capacity but engine temp runs at between 103 and 108 degrees.

[computiNATEor]

Ahh........back to the reason for this thread

I'm very keen on this mod but the fan and coupling work out ot £230 over here in the UK so that's a bit of a downer but anything that will keep the cooling system running more efficiently is a good move in my book. The Alpina 4.6 is fitted with the BMW tropical radiator for the M62 which I believe has a bit more capacity but engine temp runs at between 103 and 108 degrees.

What's the part number for the "tropical" radiator? Is it the same as the M5 radiator?

[BarryM]

What's the part number for the "tropical" radiator? Is it the same as the M5 radiator?

PN for the standard 540 radiator is 17111436061 and the tropical one is 17111436063 according to RealOEM they only fit the M62 and not the S62. I fitted this back in 2013 and at the time I noted the tropical rad was a bit thicker than the one it replaced so I guess it had been replaced with a standard one at an earlier time. I've only done 20k miles since then but as I mentioned in my previous post the engine runs between 103 & 108 but that's obviously down to thermostat and I'm happy enough with that as it's how BMW/Alpina intended...

[jicaino]

It's the same but he core has about 8 mm thicker section tubes. Less than the M5 version, but more than the 540i version. Now, if I were to do things all over again, I'll just use the regular radiator and the 88°C thermostat. That eliminates the need for "better, bigger" radiators as it's the bottleneck of the cooling system in the V8 cars.

[geargrinder]

Clearly the tropical would fit the S62 car since the regular radiators interchange. But if M5 is bigger then hard to say why bother w the tropical. I intended to go M5 next time but got hooked up with a virtually new used OE radiator and set of hoses so, I'll likely use that when the time comes. In theory w the 88C you're putting more heat out the radiator so in theory from a thermal viewpoint a bigger radiator might be a good idea, however the stock one seems to be more than fine, and the real problem we fight is the pressures. Better rads w the 88c theoretically might ease the load on the fans of course so there's maybe still a little logic there...

[computiNATEor]

10% here, 10% there, soon enough we’re talking about real upgrades.

As far as a I can tell, it really seems to be easiest to just drop in an M5 radiator. They’re all interchangeable, right? Of course, there is the lovely M5 tax.

[jicaino]

Clearly the tropical would fit the S62 car since the regular radiators interchange. But if M5 is bigger then hard to say why bother w the tropical. I intended to go M5 next time but got hooked up with a virtually new used OE radiator and set of hoses so, I'll likely use that when the time comes. In theory w the 88C you're putting more heat out the radiator so in theory from a thermal viewpoint a bigger radiator might be a good idea, however the stock one seems to be more than fine, and the real problem we fight is the pressures. Better rads w the 88c theoretically might ease the load on the fans of course so there's maybe still a little logic there...

If you're puting more heat thru the core you're actually putting MORE load on the fans. Just sayin'.
I drove about 1000+ miles on the stock radiator (non hot climate version, just the regular jane rad) with the 88°C stat. Coincidentally it was the summer and it was a hot one. I came to 2 realizations: A) I had blown a sh*tload of cash in a totally unnecesary bling all alloy radiator that at the moment I hoped to be plug and play (yeah, sure) and B) having to reinstall my clutch fan because of A/C, the woooooooooshing sound it used to make in the past summers (or whenever I tried to emulate Ceccotto) was gone.

IMHO the only reason to go to an M5 radiator is the expansion tank difference (it's better designed) since the internal volume is neglectable (over the tropical climate version) We're talking about less than 10% of volume with the same core area. What's wise to do is use a standard hot climate version radiator if you're going to pound on the car or have FI or want to be at ease while you sleep.