Car temp overheats on highway at 75mph plus or minus when AC is on.
Out of town so had to keep going.
Temp came down when I put AC temp to 90 degrees and engine temp came back to normal. Drove 2 hours like this and no issues except hot hot hot
When we exited highway and drove on on city streets at 30-40mph with the AC back on and the engine temp stayed normal.
Why is it overheating at 70-80 mph but not at lower speeds? Any thoughts, thanks!
Car temp overheats at highway speeds
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Towncivilian
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2012 Infiniti G37 Sedan 7A/T - Location: Florida, USA
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Re: Car temp overheats at highway speeds
How is the coolant level in the overflow reservoir? Have you ever had a coolant flush or radiator drain & fill?
Inspect your radiator cap according to this TSB and replace it with a new OEM one if necessary.
Inspect your radiator cap according to this TSB and replace it with a new OEM one if necessary.
Re: Car temp overheats at highway speeds
Thanks town, I'm going to check the radiator cap.
Other factors: the outside temp was 95 degrees. Also, when the car first started to overheat about 30 minutes into the trip, pulled over and two things: the coolant was bubbling over/out the reservoir so I let that cool down and it receeded, I added a little coolant but it appeared to be at the right level to being with. The second thing worth noting, the air intake cover where the air filter is was off center so a complete seal was not there, somethin got under it and caused it to get off, I recenteed and bolted it back in position. Initially thought this air flow not being sealed was related but we drove 2 hours with AC on 90 degrees in order to keep temp down.
Later in the evening we drove 3 hours (outside temperature was now 75) and we drove the entire way with AC on normal cool air 69-72 and the car engine temp stayed normal just at or below the middle of gauge.
Today we drove the car around town a few more miles all was still well and get this, the service engine light went off (ie whatever set it off initially was corrected and didn't occur again for the 150 miles or so required before a corrected problem turns off light.
So, what could cause overheating but then fix itself and be ok. Something clogged up a valve in the cooling system? I'll prob as town said and get a coolant radiator flush.
Sorry for the long post, hopefully it makes some sense.
Other factors: the outside temp was 95 degrees. Also, when the car first started to overheat about 30 minutes into the trip, pulled over and two things: the coolant was bubbling over/out the reservoir so I let that cool down and it receeded, I added a little coolant but it appeared to be at the right level to being with. The second thing worth noting, the air intake cover where the air filter is was off center so a complete seal was not there, somethin got under it and caused it to get off, I recenteed and bolted it back in position. Initially thought this air flow not being sealed was related but we drove 2 hours with AC on 90 degrees in order to keep temp down.
Later in the evening we drove 3 hours (outside temperature was now 75) and we drove the entire way with AC on normal cool air 69-72 and the car engine temp stayed normal just at or below the middle of gauge.
Today we drove the car around town a few more miles all was still well and get this, the service engine light went off (ie whatever set it off initially was corrected and didn't occur again for the 150 miles or so required before a corrected problem turns off light.
So, what could cause overheating but then fix itself and be ok. Something clogged up a valve in the cooling system? I'll prob as town said and get a coolant radiator flush.
Sorry for the long post, hopefully it makes some sense.
-
Towncivilian
- Posts: 4868
- Joined: Sun May 23, 2010 10:21 am
- Car: 2001.5 Nissan Pathfinder SE 3.5L 2WD A/T
2007 Nissan Altima 2.5L CVT
2012 Nissan Sentra 2.0L CVT Special
2012 Infiniti G37 Sedan 7A/T - Location: Florida, USA
- Contact:
Re: Car temp overheats at highway speeds
Coolant puking out of the reservoir sounds like a bad rad cap to me.
How many miles do you have on your QX4? If it's never had a coolant flush, some deposit formation is certainly possible. I would get a flush at the dealer, specifying the new blue long-life coolant which is 100% compatible with Nissan's green which is what was from the factory. Bring a print out of this TSB just in case the service adviser says it's a bad idea or something.
Also try cleaning the condenser of any bugs and dirt and such with Simple Green and a garden hose (low pressure of course).
How many miles do you have on your QX4? If it's never had a coolant flush, some deposit formation is certainly possible. I would get a flush at the dealer, specifying the new blue long-life coolant which is 100% compatible with Nissan's green which is what was from the factory. Bring a print out of this TSB just in case the service adviser says it's a bad idea or something.
Also try cleaning the condenser of any bugs and dirt and such with Simple Green and a garden hose (low pressure of course).
Re: Car temp overheats at highway speeds
156,000
I'm going to inspect and replace if needed the radiator cap as well likely do a flush. I might check thermostat too...
I'm going to inspect and replace if needed the radiator cap as well likely do a flush. I might check thermostat too...
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Towncivilian
- Posts: 4868
- Joined: Sun May 23, 2010 10:21 am
- Car: 2001.5 Nissan Pathfinder SE 3.5L 2WD A/T
2007 Nissan Altima 2.5L CVT
2012 Nissan Sentra 2.0L CVT Special
2012 Infiniti G37 Sedan 7A/T - Location: Florida, USA
- Contact:
Re: Car temp overheats at highway speeds
Thermostat is a possible culprit too, yes. You can check it by removing it from the vehicle, then submerging it in a pot of boiling water to see if it opens and closes properly. This procedure is described on page LC-18. Test any new one you purchase as well before installing on the vehicle. Get a dealer thermostat & radiator cap if you decide to replace them.