Have had my g35 2008 sedan for a year now and it has 184k miles, recently got o2 sensors put in, radiator flush ,radiator cap replaced, water pump replaced. I was having problems with air being trapped in my radiator for awhile till I was able to afford the repairs. But after I got everything done my temp guage still acts funny and goes up a little sometimes then goes back down to normal temp. Sometimes it gets high but not all the way but will come back down eventually. It doesn’t come back down fast sometimes but it usually eventually does. I asked my mechanic if they replaced the thermostat because I’ve done some research and saw others had similar problems and that the thermostat was the issue. When I asked them they couldn’t recall if they did replace the thermostat then they never actually told me if they did or not. The last time I took it too then was a few days ago and I got it back and they just told me a hose was the problem. But I’m still having this issue occur. It doesn’t happen immediately when I start driving the car but after awhile when I’m doing my delivery’s at night for my job it starts to act up. My fans kick on immediately and that’s when I know it’s getting hot.

 

How is it that both you and your mechanic have no records?
Don't they give you a copy of an itemized statement of parts and labor?
One of the things that I've learned over my fifty years of driving is I no longer trust any independent so called mechanics.

The most likely culprit of your problem is an air bubble in your cooling system?
With an eleven year old vehicle with 184k miles if you do not know whether the thermostat was ever replaced, you in my opinion, should just go ahead and replace it, do a coolant flush and be sure to purge all the air out of your cooling system.

Telcoman

 

I'd find a new mechanic, something is definitely fishy about this.