So I have a stock 04’ G35 with only cooling mods such as a Mishimoto radiator and fans with Nismo thermostat. I properly bled the coolant of any air and the car runs fine until it’s get above 100F degrees outside. When driving in 60 to 70 degree weather the water temp stays at about 172 to 182. As the day goes on it gets to about 98 degrees outside and the water temps jump to about 203 to 210 and climbing when just idling. When continuing to sit the temps climb until I start driving. Although the needle stay in the middle until around 215 I don’t think the car should be this hot, being as it’s stock with aftermarket cooling. But I do live in Southern California where I see temps around 100 degrees all the time so I don’t know if that is it. I seen that the mishi fans aren’t that good and stop and go traffic so people go with Spal or something else. Also I’ve seen a “pathfinder” mod which is a little more complicated but helps cool the rear more. And I just want some advice on what I should do next in helping the car to stay cool. I would like to also add that my car has no codes with only 128k miles although I’ve noticed a loss of power when flooring it and a difference in sound from the car. I don’t know what could be the problem, if anyone can point me in the right direction, I would rather diagnose this myself than pay a couple hundred bucks.

Since it isn't overheating (or it's at least holding the line) when you're underway, the first thing I'd suspect is that your Mishi fans simply aren't doing the job. That can be a supply voltage or ground problem and not necessarily bad fans, so I'd make sure both are good before looking at alternatives. But if your power/ground checks out, it sounds like those high desert temps are just too much for the fans.

Yeah the fans are good no problem their only about 4 months old, the car only ever overheats if sitting for more than 20 to 30 minutes just idling or when going uphill with a/c on. Other than that the car runs fine. If I was to replace the fans what would you recommend I go with?

Which Mishis do you have? Mishimoto makes good stuff, they may just be undersized. And are you sure they're wired correctly? I can't get specific without knowing which exact model you have, Sedan/Coupe and A/T or M/T. The fan setup is different depending what you have. However, they all use 2-speed fans with multiple relays, so if the wiring isn't mated correctly, it's possible your Mishis are working but not kicking on the right speeds.

VStar650CL wrote: ↑

Mon Sep 26, 2022 3:16 pm

Which Mishis do you have? Mishimoto makes good stuff, they may just be undersized. And are you sure they're wired correctly? I can't get specific without knowing which exact model you have, Sedan/Coupe and A/T or M/T. The fan setup is different depending what you have. However, they all use 2-speed fans with multiple relays, so if the wiring isn't mated correctly, it's possible your Mishis are working but not kicking on the right speeds.

2004 Infiniti G35 Coupe Auto Trans, I’m running the 350Z Mishimoto fan shroud, the connectors are the same as the old OEM fan shroud so it’s plug and play no wiring done at all. They come on when the car gets around 203 with no A/C and when the A/C is on the fans stay on the whole time which keeps the car cooler than with no A/C. I believe the fans are two 12 inch fans pushing 1100 CFM each according to Mishimoto’s website. So 2200 CFM for the fan shroud.

I just checked the FSM and it looks like both the fan behavior and temps are both pretty normal. See EC-466 here:
https://www.nicoclub.com/service-manual ... 4%2Fec.pdf
Seems like Infiniti designed your ride to run a little bit toward the hot side, but I kind of wonder if that isn't an early design hangover from the bad old days of clutch fans. Either way, in those SoCal temps, if you want to kick the fan on low speed at an earlier temperature, it's easy to do with a temperature switch and a box relay parallel to the low speed relay in the IPDM:

VStar650CL wrote: ↑

Mon Sep 26, 2022 5:04 pm

I just checked the FSM and it looks like both the fan behavior and temps are both pretty normal. See EC-466 here:
https://www.nicoclub.com/service-manual ... 4%2Fec.pdf
Seems like Infiniti designed your ride to run a little bit toward the hot side, but I kind of wonder if that isn't an early design hangover from the bad old days of clutch fans. Either way, in those SoCal temps, if you want to kick the fan on low speed at an earlier temperature, it's easy to do with a temperature switch and a box relay parallel to the low speed relay in the IPDM:


G35 Early Fan.jpg

Thanks for the info and I’ll try to give your idea a shot, do you know how I would go about wiring up something like that to switch the fan on earlier?

Most of those switches are grounding types with one terminal and ground contact through the body of the switch, so you'd need to find someplace to screw an extra sensor into the cooling jacket. If there isn't anyplace, you can use a 2-wire type and a brass tee into one of the auxiliary coolant lines (the throttle body or oil cooler inlet lines are both good spots). These are some examples:
1-Wire: https://www.ebay.com/itm/311784525200
2-Wire: https://www.ebay.com/itm/304288101630