Today, the weather was about 85 degrees in San franisco downtown area. I drove from sfsu over to Laguna Honda and then downtown taking local all the way. Once i hit the stop and go traffic,

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2-3 months ago
My car has overheated before and i wasn't sure why. but when it did, the weather was 98 degrees and i was sitting in my car with the ac on full blast and engine off.... I drove home and about half way there, my engine temp was in the red zone! i pulled over, looked at my coolant and it was boiling in the little tank. Thank god i was only 2 blocks from Kragen so i bought some coolant right away and i filled up almost 2/3 of a gallon! I checked for leaks and cracks in my hoses but everything was fine. my radiator/engine fan didn't work and I ended up burning my AC clutch compressor.
this was almost 2-3 months ago. I replaced the radiator fan ever since its been fine since i refilled it with coolant. now my eyes are stuck to my temp gauge....

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TODAY

i noticed my temperature was going up. Usually its just about half a dash right under the middle, but today, it went up about 2 notches over the middle. This was with very slow traffic. I checked the coolant in the morning before i headed out to and both reservoirs were filled up. After returning home and having the temp gauge hit above what is normal for me, i checked both reservoirs agian when i got home and it was still the same.

but the weird thing is, when i speed up and allow more air to blow thru my grill and cool the engine down, the temp gauge drops back down to normal for me.

hmm.... i even got out of the car to make sure my fan was working in the front.

anyone have any ideas?

 

i would think it would have to do with your fans/coolant like you've been checking... hmmm try again make sure all hoses are clamped and no leaks.. etc..

 

You might have a slow leak in the head gasket or there's a bubble in the system. The system needs to be either bled to let all the air out. If you have a slow leak in the head gasket you will be burning coolant and might get a check engine light for misfire. Make sure the fans are kicking on...Last thin might be your temp sensor might be bad.

 

hmm... any particular type of shop i can take it to aside from the dealership?

 

Any shop can look into it...I preferred nissan certified shops if you can find any...

 

You're not boosted or anything right?

I am not sure how it is on N/A G's as I NEVER paid attention to my water temp gauge, but now I do a lot. If I am sitting in traffic, my water temp will slightly rise as the car should be moving to help it keep cool, and on hot days if I am driving for a while and hit boost enough the temp will definately get really hot, so I try to stay out of boost when I am driving for a while and when its really hot out.

 

Use an OBD2 scanner to read what the ecu sees as the coolant temperature as a double check on interior gauge [they have separate sensors].

Anytime the coolant exceeds 200F you are at the start of summer over heat protection mode and the ecu cuts ignition advance back thus power output falls.

 

When my car was not FI, the temp gauge would go to half on the dial. There was nothing I could do to move it - slow traffic, WOT and stop - nothing. I don't know what year your G is, but you might check the thermostat as well. (Always best to check the easy stuff first.)

 

hmm the exact same thing happened to me back when i had my civic, and the intitial thought was that it was head gaskets, but then they found out it was the electrical system(dont know what that includes)but it fixed the problem completely. take it to a shop, just my .02

 

hmm think i'll go get my car scanned this weekend. As for thermostat, how do i check that?

 

Check the thermostat, flush out the coolant system add some water weter and distilled water and go from there (make sure you get all air out of the system).


Matt

 

i thought it was normal for a car to run warmer in high-heat and humidity (radiator is much less efficient) and slow traffic, esp with the a/c running. usually if you start moving more, more air gets brought in, your water pump spins faster (with engine speed), also, if your idle is low, you won't be moving enough coolant to absorb the heat from the engine. (found that out the hard way on a motorcycle with a bad tach)

try popping it into neutral and give it a shot of gas, will probably drop quickly enough...