Engine runs hot when decelerating

Hi,

The problem only happens when you slow down from highway speeds? Interestingly, one would thing the opposite would happen. Tell me. Have you checked engine coolant? Is it clean and full?

https://www.2carpros.com/articles/engine-cooling-system

Let me know. Also, let me know if it happens all the time.

Take care,
Joe

Hi,

If it is doing it all the time, and gets that high and then drops, it sounds like you have a thermostat sticking or maybe even the temp sensor is bad. I hate to ask this, but when it shows 260°F on the gauge, does it seem as though the engine is actually that hot? For example, is there any coolant sounds, steam, or coolant coming out of the system? I would hate to say replace the thermostat and find that isn't the issue and that the engine really isn't that hot.

The strange thing about this is that it happens at highway speeds and not in town. That is the opposite of the normal overheating issues.

If you want, here are directions on replacing a thermostat. You can check the old thermostat by dropping it into boiling water to see if it opens. However, once it's out, I would just replace it, but that would be your decision.

https://www.2carpros.com/articles/replace-thermostat

Since it drops as fast as you described, I suspect it is the thermostat sticking, but a faulty temp sensor should also be considered. I do have one other thought. Is the cooling system pressurizing when it is at operating temp? In other words, do the radiator hoses get hard from pressure?

Let me know.

Joe