So I knew that the temp gauge was filtered or weighted, whatever you want to call it, so that it doesn't constantly move due to small changes in temp. However, I would not call a 30+ degree change in temp a small change.

I have always thought that this car seemed very susceptible to power loss from heat soak, but now I know just how bad the problem is. I got my Ultra-Gauge OBDII scanner in the mail yesterday and immediately plugged it in. An all highway drive to work this morning resulted in temps of 185-190 which seemed pretty normal. Went out to lunch and sat in a drive thru for a few minutes and temps quickly rose just above 220, yet the temp needle did not move! So just when was the needle going to tell me that the engine was about to overheat?!!!

I know I probably have an airflow issue, so thinking about whether to replace the fan clutch or do an e-fan conversion. May just throw in a larger capacity radiator while I'm at it since I'm at 140K. Anyway, my point to everyone else is, DON"T TRUST THE STOCK TEMP GAUGE!!!!

 

A lot of cars are that way by design. Manufacturers figure the average car owner is not smart enough to figure out what the gauges really mean. These days, a lot of cars with oil pressure gauges and water temp gauges are merely idiot lights. A lot of cars don't even have oil pressure gauges anymore.

I've installed auto meter gauges in cars before to watch the water temp and oil pressure gauge rise and fall while the factory gauges never budge from dead center.

Never trust any factory gauge

 

That seems like a normal temp while parked. Often vehicles with electric fans won't even turn on the fan until 215-225°F. Worry if you see 230°F. Just checked the 2006 manual, and the fan starts low speed at 208°F and high speed at 212°F.

 

I would agree that 220 is probably not going to damage anything, but I was using this thread as a benchmark for normal temps.

https://g35driver.com/forums/engine-...ky-worthy.html

Either way, it's higher than I want it to be. Heat is like kryptonite to this car. I've never seen a car fall on its face when it gets hot like this one does.

 

But EFI engines also operate to max efficiency in the 180-210 degree range. It's not like the old carb days where a HP trick was to install a colder thermostat to keep the coolant in the 160-180 degree range and make power. Do that to a modern fuel injected engine and you run risk of long term damage such as increased wear on the engine, more fuel consumption and damage to emmissions controls such as cat converters.

I agree that cars get doggy when they get hot, but not much you can do really. If you have a custom tune, you can mod the fan to come on at a lower temp perhaps. If you can keep the engine in the 185-195 range, you would be golden...but a healty WOT run will temp send temps to 210-220 degrees on most engines

 

Yeah, I had the same reaction as you... I think I actually posted about it somewhere on here, but I can't remember for sure.

My temp gauge moved up a few weeks ago when I left it running, sitting in the AC for about 40 mins in 100+ deg weather, and I pulled my netbook out to read it was just over 220. That worried me a lot, but throwing the heater on full blast and driving the car ~55 for a while cooled it back to normal operating range pretty quick.

It got me to thinking though, that I too had heard the gauge was "center weighted" but didn't know just how much, so the next morning, I plugged in the netbook from a cold start, and the gauge hit it's normal centerline reading at about 165 deg
FIFTY DEGREE RANGE and it doesn't move AT ALL, not one tiny mm

By and large, people aren't even going to worry about the temp gauge unless it gets unusually high, near the top... I shutter to think just how hot it would have to be to read that
So basically it doesn't tell you anything except when you're screwed. Way to go Nissan!

 

+1 to what's posted above - the stock temp gauge/needle doesn't tell you much about what's going on with your coolant temps. A digital gauge plugged into your OBDII port or a standalone gauge is the way to go if you really want to know your temp.

 

^This.

Also, you have to take into consideration density air conditions. Once temps get into the 80s, the concentration of oxygen becomes lower especially in more humid conditions. Right now in Kansas City, it's 101 degrees, 37% humidity, and a 29.9 baro pressure. Altitude is about 1,200'. The air density (ie density altitude), is 4,500' above sea level. That means my car is loosing about 9% of it's power solely to the air conditions. So instead of making about 235whp, it's only making 215whp. Then factor in a hot engine which is ingesting even hotter air and losses go up even more. My point is you could adjust some things to reduce heat soak and the ECU's conservative nature in hot conditions; however, you can't tune horrible atmospheric conditions which are largely responsible for the muddy performance.

 

220 is normal idle temp.

second: there is no reason to upgrade your cooling system if there is a problem. If there is a problem (which i think this is completely normal) then fix the problem instead of adding aftermarket parts. People jump right into "i need a big radiator" if they are over heating. Well, the car came with a sufficient radiator to be a reliable car so if it's not working properly fix the problem first.

My car on low boost is 523 hp and i have a stock radiator with no cooling issues so the oem system works perfectly fine when functioning normal.

about the gauge being all the way to the top. when i blew a head gasket my temp gauge went almost to the very top. My datalogs said the peak temp was 242* which is up there but not "danger" limit just yet so the stock gauge is pretty dummy proof. Don't scare the people unless they need to be scared.

 

220 is normal idle temp.

second: there is no reason to upgrade your cooling system if there is a problem. If there is a problem (which i think this is completely normal) then fix the problem instead of adding aftermarket parts. People jump right into "i need a big radiator" if they are over heating. Well, the car came with a sufficient radiator to be a reliable car so if it's not working properly fix the problem first.

My car on low boost is 523 hp and i have a stock radiator with no cooling issues so the oem system works perfectly fine when functioning normal.

about the gauge being all the way to the top. when i blew a head gasket my temp gauge went almost to the very top. My datalogs said the peak temp was 242* which is up there but not "danger" limit just yet so the stock gauge is pretty dummy proof. Don't scare the people unless they need to be scared.

 

I remember this story from a while back.

On a forum I frequent, there are a few ex-Ford engineers. Being an engineer myself I've had some conversations with some regarding "why" they did this or that...

Anyway, back in 1996, Ford installed a genuine oil pressure gauge in the 1996 Cobra. The standard v6 and GT got the "center-weighted gauge, but the Cobra gauge would actually rise and fall with the oil pressure. Ford figured cobra buyers would be performance minded and want a real gauge and not a dummy gauge...


It lasted 1 year. Any of you guys that have seen a real oil pressure gauge knows the pressure can rise and fall pretty good on a hot day with hot oil. Well apparently the "real" gauge freaked people out who would watch the gauge bounce around as they drove. Apparently, people are used to dummy gauges that just point dead center to normal.

 

^I can understand the logic, but freaking 50 degrees is insane.
The motor's normal operating range does NOT vary by 50 deg. More like 180-210 or so? That's 30deg, make those 30 deg the center, and then let it go up or down a little bit. 99% of the time, it's not going to leave that 30deg span anyway, and if it does, it's probably because of an extenuating circumstance (like idling with the AC on for too long, or insufficient cooling due to conditions, or a problem with the cooling system)

 

Well, I have cooled off, so to speak and 220 is not freaking me out as much since it's only at idle in extremely hot conditions. Temps at speed pretty much stay at 185-195 which is fine. I think my issue is lack of airflow at idle caused by a weak fan clutch. When I spin the fan by hand immediately after a hot shutdown, it has about the same resistance as when cold, which I think is about 20-30% engagement. A new Hayden fan clutch is on the way which I feel pretty confident will knock the top end off of those idle temps a bit. I'll post back up with the results. Thanks for all of the advice guys.

 

crappy thermal fan. same that's on my truck. get a stactic fan or switch to electrical fans like other g35's and you'll be fine.

And there is only a 40* weight. After 220 the gauge rises rapidly because 240 is at the complete top of the gauge.

 

^Actually, it hit's the centerline at 165* so if it doesn't start moving until 220, that's a 55* weight, not 40*