I noticed that my coolant light was coming on briefly during hard acceleration about a month ago. So, I went to a local Ford dealership to get coolant adhering to the WSS-M97B44-D spec as mentioned in my manual.

I opened the reservoir cap and noticed that it needed about 8 oz of coolant to be at the bottom of the cap. What I didn't notice was a gold color to the existing coolant. Hmmmm, I wondered, did the previous owner switch coolants?

Reluctantly, I poured a bit of the gold stuff into the reservoir.

About two weeks go by, and I notice that the radiator fans have been staying on after the car is turned off, even though the temp gauge never moved above the middle mark. The fans had not done this before. Fast forward another two weeks, and today the temp gauge started to approach the red zone for the first time.

So, I'm thinking that I may have an issue from mixing two different coolants. I plan to do a chemical flush this week. Are there any other issues I should be looking at? Considering the behavior, any chance the problem is the thermostat?

 

Sounds like a new thermostat would be well advised in addition to the flush. It is probably best not to run the car until this is done.

 

Check the age and consition of the Thermostat. Then the water pump.

Don't let this engine overheat or you will have really big problems. The stock temp gauge is not sensitive to anything but "OK" and "TOO LATE", don't rely on it! See the discussion on Realgauge eslewhere on the forum for a solution to that...

 

+1, A classic symptom of a Failed Thermostat. Replace it immediately.

 

OK. A trip to the Jag dealer for a thermostat. May as well knock that out along with the chem flush. Thanks.

 

+1 to the Thermostat

You also need to investigate the reason for the initial coolant loss that alerted you to the issue.

The Temperature Gauge is next to useless. The V8 can seriously overheat long before it moves from the centre position. Check the link in WhiteXKR's post to his website. The information there on his RealGauge explains about this in detail.

Graham

 

Just finished the chemical flush and swap of the thermostat. The PDF in the FAQ section was superbly helpful. The only think I did out of order was the swap of the thermostat. I did that before the first flush since it seemed that the thermostat was bad.

The only other thing that I should clarify is the color of the coolant. I had originally stated that it was gold, but I think the color of the correct coolant is orange. Coolant following the WSS-M97B44-D spec as required for my model is available at any Ford dealership. Just don't trust them to give you the correct stuff. Read the label yourself.