The last couple of weeks my temperature guage has been scaring me. It increases really fast, almost at the point where it reaches the warning line. Today, after driving for like 20 mins it went 3/4 of the way , then it would go down to the halfway mark. It seems like it would go up when I go uphill most of the time. I filled my coolant last week and had it flushed out like 9 months ago. Anyone have a clue? Is it suppose to go up and down like this?

 

No it shouldn't go up and down like that. It sounds like the thermostat is sticking but I would also make sure radiator fans are operating okay.

 

unless you wanna pop a head gasket and get hit with a HUGE repair bill

 

on flush n fill: air pockets maybe?

on adding last week: Are you adding because you're losing coolant somewhere?

Sticking thermostat sounds plausible, as does blocked radiator, cooling fans not working, water pump, etc. Maybe a pressure test to find a leak?

ARFF

 

Like Karguy posted, fans not kicking on and a sticky thermostat are the most likely problems.

 

Yeah, what you say is no joke. Especially when heads/block are aluminum and not cast iron.

If the gauge is functioning properly and the sensor in the block, then thermostat would be the first thing to check. If that's fine it could be the water pump (but that should give a hint by leaking or whining). If that's not it then the radiator could very well be the problem. Cooling is not rocket science at all. It's simply amazing how much is at stake with a cheesy thing called the thermostat. Whadda those things use, wax and a spring or something to know when to open and close? Good luck.

 

Took it to the shop today. Ran some test. Couldn't find any leak. Check the temp. guages and it seem fine. Drove home and it looks fine now. Mechanic said don't worry and come back if the car acts up again. . Thanks everyone for their input.

 

From personal experience, if it is your fans, it will get hot while idling, and cool down while moving. Your AC will really get warm at idle, also (even just stopped for a red light). Thermostat, fans, radiator fins, water pump (but would give other symptoms, like leaks, noise) are all good possibilities. Keep an eye on your gauge if you're gonna keep driving it. My '97's gauge stays rock steady just a tad under the horizontal (half-way point). Never has gone past that, and my '96 was the same way except when my secondary cooling fan (passenger side) was inoperable. But then it only went up a little more at idle, and the AC got warm. BTW, I live in Louisiana, so 95+ weather is common. Have you done any fiddling with the engine? Don't know about the Maxima, but older cars I've had would run warmer if they were running lean. Anyone have any ideas on that, or is that not a possibility for us?

Dave

 

Here's my theory as to why the mechanic couldn't find anything. The cooling system hasn't been flushed yet, so a piece of scale broke off and was circulating in the system. It managed to impede the operation of the thermostat causing the erratic symptoms. By the time you visited the mechanic, it had dislodged and the thermostat was operating normally. Does that sound plausible to everyone else?

 

thermostat is like $8 (at least is it for a sentra)