Nissan Repair: Altima overheating, temp guage, nissan altima

Question
Hello,

I have a '05 Nissan Altima w/ a 3.5 engine size. Recently my temp. guage has been showing an above avg to high reading. The first time I noticed this was while traveling uphill with A/C on. I live in Central CA where the summer is often 100+ and do realize that one should not run their a/c on steep inclines so I turned the A/C off,...the temperature did drop back to an acceptable range.

Unfortunatley, this symptom has now progressed. We just took a road trip and had to nurse the car home upon realizing the temp guage is spiking now even on flat ground with no a/c on.

When I check my radiator, it is full of good, clean antifreeze which I have kept flushed and replaced regularly. I can hear and see both rad. fans spinning constantly and my upper rad. hose feels somewhat soft still so it does not appear to have an overly high ammount of pressure. I was able to open the radiator cap with no pressure either.

I had to run the heater all the way home in an attempt to manage the temp showing on the guage but even with the heater on full,..the car showed a very high temp reading.

I am thinking it could be the temp sending unit or a thermostat but would welcome your expert opinion. I also wondered if perhaps the rad fans have multiple speeds? If so, perhaps they are not kicking into high speed??

One last thing I noted....when I turn the hot car off, the rad fans do not continue running?

Thanks in advance for your time and advice.

Todd

Answer
Hi Todd -

Thank you for the information. Very thorough and precise. I appreciate that.

First thing I would do is check the thermostat. One quick way is to get the engine up to operating temperature, or when the temp gauge starts to rise to abnormal. Feel the top radiator hose, then feel the lower radiator hose. If the lower hose is much cooler, then the thermostat is stuck closed. Need to replace it.

The fans only have one speed. However the motors could be going out and that would slow the speed down. Since I cannot see it running, the best way is to let a competent mechanic take a look while the fan is on, and he would be able to tell.

Hope this helps -
aloha
calvin