The other day in my driveway in 44 degree weather my Q went to 250 degrees. I was idling the car at 2,000 rpms. I've been using the bluedriver obd2 code reader/monitor.. I have noticed driving around it stays around 190-196.. I have a 1 year old radiator, new thermostat, new Nissan coolant, 2 working fans, and fresh oil, and new tranny fluid. I've never had a overheating issue. Ever. But, idling at 2,000 rpms was to much for it.. doesn't that say somethings wrong??
I've never had a car that couldn't run all day and night in this situation....

I wouldn't call 2,000 RPMs idling, more lIke racing the engine. The factory idle spec is around 700 RPM. If the cooling fan was working, then I'm guessing it just didn't have a good source of air. Were you parked against a garage door or any other obstacle?

And was the new coolant mixed with equal parts distilled water to get a 50/50 mix?

Nothing in or around the car.. and as for the coolant, it was done 50/50 by my request at a shop with distilled water...

O5Q45 wrote: ↑

Thu Dec 21, 2017 6:10 am

But, idling at 2,000 rpms was to much for it.. doesn't that say somethings wrong??

Definitely!

In good condition, the cooling system should be able to handle idling in 100+ degree weather. In 44 degree weather, it shouldn't even be breaking a sweat.

Is your replacement thermostat Nissan-branded OEM? Problems with aftermarket-branded thermostats seem to be pretty common around here.

Are you sure the thermostat is installed correctly? There's a "jiggle valve" that needs to be positioned at the top of thermostat housing.

The next time you notice it running hot, you might try spraying the radiator with a garden hose. If that doesn't reduce immediately reduce the coolant temperature, you may not be getting any coolant flow through the radiator (perhaps due to thermostat or water pump problems).

EdBwoy wrote: ↑

Thu Dec 21, 2017 11:33 am

I wouldn't call 2,000 RPMs idling, more lIke racing the engine. The factory idle spec is around 700 RPM.

Yep - If the engine refuses to run at anything below 2000 RPM, that's not normal, either.

I am not getting the full story/picture from OP, but you're both right. Even when racing the engine in an open area, it shouldn't overheat. I caught the coolant replacement, but missed the thermostat part.
Although the VK45DEs are stout when it comes to the cooling system, from other subforums, people have had problems using anything other than a Nissan OEM unit.
For example:
1. post6746580.html
2. post6743186.html

Oh, replace the radiator cap too. It's cheap insurance

Fan relay, they can easily not work just once then go back to working fine, the fans then will test good all day long. Any other parts involved in the fan control overhead should be looked at too. OP should have established whether the fans were working AT THE TIME OF THE OVERHEAT, most just don't go there and much more trouble finding the problem then.

I purchased the most "liked" thermostat on Rockauto web site.. It was not a Nissan t stat. It was a safety t stat that was or is, supposed to stay permanently open after an overheat.. I had the t stat replaced by this unit with the radiator and the Nissan coolant. (Green). 30,000 miles goes by, and last month I had the Nissan Coolant replaced with new.

The reason I was idleing at 2,000 rpms is because there are several roads in my area that cause the middle of the car to scrape some. My wife also visits a patient with a driveway that desends to the depths of hell.. let's just say steep.. the car will not reverse up the driveway even when dry without wheel spin.. and so you can imagine at the top where it meets the roadway.. this is also one of several scrape areas.. last time upon pulling out she managed to run the passenger rear wheel over a curb in same driveway and absolutely destroyed the metal protective skid plate over the fuel and brake lines.. somewhere around then and the full slow/no pressure tranny flush, the car has vibrated and ran rough accelerating through 1/2 2/3 and stops vibrating in 3rd.
I ordered the bluedriver OBD2 Bluetooth code reader and have been monitoring several systems.. the car runs around 190-200 degrees since I started monitoring. I guess that's normal.. however, the other day when I pulled in I looked down at my phone and saw 204 degrees. I popped the hood, coolant reservoir at correct level, and began running 2k rpms. I watched the info I was receiving from the ECU to my reader, and watched the temp climb to 250 degrees and cut off the engine. I heard no boiling, radiator cap still sealed.. when I returned the next AM, it took the motor around 2 to 3 times longer to start but did. My driveway is wide open space..
This morning it was 24 degrees, and I went out and started the car to warm up because I Don't trust the misses to drive it proper with a cold motor or tranny.. so, monitoring from the living room, the car idled for about 15 min, and never got above 165 degrees before she left.. so, I'm guessing maybe the t stat is locked open... Yes, both fans were on. I believe the secondary came on around 206-210.. sorry for the book.... But that's how it all came together...

Thanks for the additional info. So it just "ran hot" and didn't actually "overheat", correct? I can't remember what temperature exactly, but if it really overheats, the screen will tell you accompanied by an OBD code for "engine over temperature" and CEL.

My suggestions:
1. Give it time.
Next time you rev up the engine to 2,000 rpm, you'll probably see a high reading. Wait a little while for the cooling system to work and remove the heat.

2. Don't abuse the car.
I know you've mentioned the warming up before a drive previously. You know your wife better, but unless she is a racer of some sort; normal driving does a better job of warming up and maintaining a car's vital systems than idling, especially at high rpm.

3. Try OEM
If I'm following correctly you do your fluid exchanges and other stuff pretty frequently. This is a good thing, if the intention is preventative maintenance. I'd use OEM components since (especially such a reliable platform) millions have been spent on the research of what is best for this car. Cut the guesswork & frustration of reinventing the wheel.

We can get to the running rough issues later. Aftermarket air filters etc, but I'll hold off speculating until a code pops up.

Stay warm out there and have a joyful holiday season.