Yup using an ultra gauge. Love the peace of mind especially for engine temps

 

Right on, I'm with ya!

 

Well bad news, drove to work this morning and the spikes are back. Upwards of 220 and frequent. The only thing I can think of is the thermostat isn’t opening early enough or I still have air in the system. Maybe that small water pump mating surface leak is slowly drawing more and more air in.

 

Also check that no leaves or mud are outside the radiator preventing air flow.

As a temporary measure you can disconnect the AC compressor from under the hood. Now you can turn the AC on and it will power up the condenser fans to help with cooling. 220 is too high for me to be comfortable with.

Do you know how old the water pump is? Is the pump making any noise?
Thermostat is a good fix and easy on the wallet. Make sure to get the proper gasket, and you'll need to absolutely clean off the old gasket.

Do you hear the loud sound of the fan clutch when you first drive off?

 

So there’s nothing blocking the outside of the radiator, and the water pump is. Brand new I changed it with the new heavy duty fan clutch I put on. I can definitely hear the fan clutch it’s really loud.

I changed the thermostat at the same time as the pump and clutch too. I used a stant superstat that I saw on this forum. Maybe I got a bad one, I’ll probably get a new one and test it in some hot water or something.

 

Reservoir pressurized cap condition?
Hoses?
Any of coolant leaks besides the one near the thermostat?

 

No coolant leaks besides the very tiny one, hoses are all in good condition no dry rot or cracks, and the reservoir cap seems fine, i can hear it release pressure when I take it off after just running.

 

Everything seems in order. May be time to for the new thermostat with gasket.

Make sure all the hoses connecting to the reservoir are good. I recall doing everything you have done and in the end it was an issue with the reservoir housing having a tiny crack that would cause a waterfall of coolant once the engine was turned off.

 

get a cooling system tester and add some pressure to the system when it is warm, check to see if it holds pressure. you then can check to cap for proper pressure release. I got my tester off Amazon and it helped me fix the problems with my cooling system. ended up being a cracked reservoir bottle and a bad cap.


for $0, you can't go wrong. It does fit on my 1997 Discovery 1 with 4.0 motor