I've noticed my OEM fan turn on a couple of times in traffic with a new KOYO full size radiator. I wanted to delete the fan, but now I don't think I will, maybe just replace it with a SPAL.

 

If only there was a way to log coolant temp...

 

^^ Doesn't Evo Scan log coolant temp?

 

Ok, i will settle this once and for all! Had this problem today in Phoenix. 104deg temp. Was driving around looking at pieces of property to buy on my day off. Running ac full blast, no problems. When i would stop, get out of car for a few minutes with it idling and get back in the temp was all the way to high(normally sits just below half way). I'd turn the ac off and/or drive at a decent speed and the temp would come down. Witnessed this several times. Noticed driver side in bay fan not coming on at all despite temp going up. Passenger side outside bay fan running strong whole time, with or without ac on. Took inside bay fan out tested with AA battery and it worked. Figured it was fan control module. $116 f****** dollars for a new one at autozone. Fan comes on and no more heating problems. Points are: 1) yes mitsu puts a second fan for a reason, duh! 2) that reason is for extreme temps. Phoenix at 104deg is extreme and sitting idling is a rare occurrence, but does occur in southwest US. So, if you live where it is rare to have temps >100deg and not blow ac at full blast and not be sitting idling, you will probably never need that fan. For those that live in az, unless you don't have ac, it would be really, really stupid to remove that fan as i learned today how quickly the temp will go up without it. Once again, problem solved by driving at reasonable speed or turning ac off, but why the f*** would anyone want to have to do that so they can remove a stupid little "bulky" fan. Just my $.02, hope this helps. I originally read this post trying to find out why my car was overheating, glad i found and fixed the problem, just hope this post can help some of you others that seem to be bickering so much, btw, power mods on my 03 evo 8 are: 2.3 stroker, fully built head, 272 cams, evo 9 turbo, 1200cc injectors, aem ems, buschar double pumper. 3" turbo back with cat delete, manual boost control. Stock intercooler and stock radiator.

 

Well, seems I knew what i was talking about after all. Fans are there for a reason. If you need more room, get a skinny one, don't delete them.

 

Stock motor + stock fan assembly = OK, never overheated
Half filled block built motor + stock fan assembly = OK, never overheated
Half filled block built motor + mishimoto slim fan = Overheats waiting in line at the autocross

My wastegate arm broke and I had to get a turbosmart which wouldn't fit with the stock fan assembly. It's funny how that one little part resulted in my overheating. I can't make it to the front of the line at an autocross session without temps going up. If I move even 2 turns into the track the temps go right back down, even full throttle at 20-30mph is enough to bring the temps down in seconds.

The radiator is a full size Koyo btw. I'm either getting a second fan or replacing the mishimoto for a SPAL or Flex-a-lite or whatever. The mishimoto definitely works, it comes on and pulls but it's weak. 90 degree days are fine, 105 degree days are not.

 

I have a koyo with the stock fan and a turbosmart WGA. You can trim the OEM fan shroud to clear the WGA.

 

Damn, wish I thought of that. Oh well, weight reduction is a one way street for me, and the only sensible solution is to spend more money on less stuff.

 

running no fan, not by choice but that's how i got the car, no problems with i believe a koyo alum rad. i noticed i had a wire hanging loose and peeps from here told me it was from the radiator fan module, never noticed my temps shoot above normal operating temps, still going to keep an eye out on fb and cl, but in the meantime i haven't had any problems *knocks on wood*