Coolant temp increase ?

[Hall]

Curious - do you have a reason to feel this is actually a problem?

As long as it isn't overheating, it's expected, normal, and completely fine.

When the gauge is climbing, sorry, I'm not going to just ignore it as "normal". When the gauge ALWAYS sits at 8 o'clock 99% of the time, when it starts climbing to 10 or 11 o'clock, you would react as well. I know my car.... Not sure either of you read my post. If I have to turn the heat on at the highest temperature and turn the fan up, that's not normal.

 

[SC Maintenance]

When the gauge is climbing, sorry, I'm not going to just ignore it as "normal". When the gauge ALWAYS sits at 8 o'clock 99% of the time, when it starts climbing to 10 or 11 o'clock, you would react as well. I know my car.... Not sure either of you read my post. If I have to turn the heat on at the highest temperature and turn the fan up, that's not normal.

Its definitely not normal.

I would still encourage you to check it with OBD. The cheap temperature sensor on the engine may not be all that accurate or may be failing itself? Possibly the difference between the two points is not all that much.

I would guess either a sticky thermostat or possibly a 2 stage electric cooling fan not hitting its second stage? If it were a radiator or similar it would be more likely to overheat at idle - which it sounds like isn't the issue?

 

[ripcord]

I had similar intermittent temp spikes on my old Ford pickup recently. It turned out to be the thermostat which looked to be the 25+ year old OEM one.

 

[bullwinkle]

Could even be an eroded WP impeller-at idle, it’s not going to move as much coolant as it used to. Or scale in the radiator, or buildup in the system in general. At 167K, anything is possible. I actually saw the Corolla crack 200F today, but I had just came off a 45 mile highway run, A/C blasting, pulling off an off ramp. Recovered quickly, though, pretty good for 170K+!

 

[SammyChevelleTypeS3]

Did you make ANY changes to the car recently? Added any coolant without taking time to bleed the air out? Changed to thicker (da da dah!) oil by any chance? Thicker oil will make a car warm up quicker than usual. Another thing to be aware of for what its worth. Honda at one time (think still do) used to all have the two cooling fans. One of them is connected to the AC system and turns on when you turn the system on. This may be of help:

https://axleaddict.com/auto-repair/Electric-Cooling-Fan-Problems

 

[someonesomewhere]

When the gauge is climbing, sorry, I'm not going to just ignore it as "normal". When the gauge ALWAYS sits at 8 o'clock 99% of the time, when it starts climbing to 10 or 11 o'clock, you would react as well. I know my car.... Not sure either of you read my post. If I have to turn the heat on at the highest temperature and turn the fan up, that's not normal.

Did read it. Hesitated to reply because you're obviously only looking for (and only being offered) doomsday scenarios. Paraphrased, "when it's really hot out, and I'm stressing the cooling system, it gets hotter but doesn't actually overheat". I've driven a dozen or more different vehicles over the years, and any that have had an actual temperature gauge have behaved that way in traffic. Sitting still, air on, over 90? Gauge creeps up. Start moving again, gauge goes back down. None have ever overheated or caused any issues.

But, sure, go ahead and throw $1k in parts at it, only to see it do the same thing in the next heat wave. No prlberbial skin off my butt, friend.

 

[Mainia]

Just how much in degrees does it change? My temp gauge on the Gen Coupe is a glorified idiot light. If I did see it move once warmed up it's probably too late and already overheated.

All manufactures purposely make it that way so they don't get inundated with paranoid owners calling to check it out. It happens to me when I should know better. The minute I got my iDash Gauge I had data that to this day drives me nuts. During winter I never get above 190 F, but summer I see 220F and I notice a tighter engine with poly motor mounts at idle when it gets that hot. It is within the parameters, but for some reason I can't fully get past it. I am hyper aware of temperature now in the summer and don't like that I am.

 

[Jetronic]

What would cause my '08 G35 (169k miles) to occasionally have the coolant temperature increase ? By increase, instead of the needle being around the 8 o'clock position, it moves to 9 or even 10 o'clock. It has ONLY done this when it's 90º F or higher, AC is on, and I'm not moving. So far - knock on wood - I've been able to turn off the AC and crank the heat and that controls it. This isn't a frequent occurrence either. In 3-4 years, it's maybe happened 7-8 times. Coolant overflow tank level is okay but it does need topped off maybe every 18 months. No signs of leaks otherwise.

When I've been able to check, both cooling fans are working. It happened today, I turned on the heat, etc and was home in less than 10 minutes. I left it idling in my driveway, AC off, and both fans were working. I am a little familiar with Hondas which tend to have 1-2 coolant temp sensors - do these have them ? No check-engine codes are triggered. How do I diagnose what it is ? If it were the thermostat, I'd think it would happen more frequently and at other times or situations but in my case, it's very consistent conditions for IF it will happen. I'm not interested in replacing random parts and crossing my fingers either.

are the fans working on multiple speeds?