Engine Temperature

[Yellow Rose]

I'm Lazy

Other than not having warmth during winter in the cabin right away, does anyone know of a technical reason to not replace a thermostat that is “stuck open”?

I promise to not mash the large pedal with the engine is still in cool-mode, as it is warming up.

 

[Autophile]

Hey Andy,

As you are an older , and perhaps even wiser engineer than me, I won't argue with what you may know as first-hand experience regarding fluid heat transfer. However, I do enjoy thinking about subjects (e.g., transport phenomena) that I haven't considered in years. Thanks for the opportunity to dust off this topic in my head.

On the topic of running with a stuck open thermostat, I discovered an interesting observation with my NSX. When I bought my car, I flew in to Houston and drove it back. It was late April, and the night time temps were pretty cold. As I drove home, I noticed that the water temp varied with the ambient temperature, and I concluded that the thermostat was stuck. Anyway, while driving at night, 45-50 ºF ambient, driving 80 mph, my water temperature gauge was completely bottomed out! I am amazed that the cooling system on the NSX is so overkill that at this speed and outside temp, the water temperature would not even register on the gauge. The car seemed to run fine, and actually, my first and best average gas mileage value (29.5 mpg) was during this 2000 mile trip.

 

[HYPERTUNE]

One drawback of not running a thermostat with a fuel injected engine is that the ecu will be running the engine unnecessarily rich (it assumes the engine is cold and richens the mixture for better idle stability, etc.) Most ecu's will be running in cold start mode untill around 70 deg. (deg C that is)

 

[hlweyl]

Autophile, I had the same thing happening to me when my thermostat stuck. In the colder weather at about 55 mph, my gauge would go back down to completely cold.

BTW, a little off topic, an old hot rodders trick to make the engine run a little cooler was to drill a small hole in the thermostat.

 

[Yellow Rose]

Phile / Hyper / Gorilla - thanks for the input......this morning we were presented with 50-ish °F. After seven miles of driving the needle was only one mark from the bottom.

Guess I have a chore to take care of on Saturday.

 

[Yellow Rose]

Part Number

Order 19301-PR7-305 for a replacement thermostat "Kit" includes gaskets. This is applicable for 1993+.....

They sent me part number 19301-P8E-A10. Do you know what this version is for? Inside the plastic bag is the thermostat and a separate rubber gasket.

 

[Larry Bastanza]

Updated replacement, you are good to go. This number is actually a CL/TL/MDX number. The NSX number is superceded by this one.

LarryB