So I keep getting low coolant warning. Its not leaking anywhere I haver checked everywhere with a fine tooth comb. I can hear it boiling and slightly splashing from the top of the expansion tank but not nearly enough to remotely drain the system a couple time. My fan doesnt come on ive noted but ive manually turned them on thru SDD and the circuit is good. I was told not bleeding the system properly can cause this but cant find out how to do that. how does bleeding the system cause it from boiling coolant ? Is it the fan controller or control module not sure.. you think....and if so where is that located. I checked a ton of fuses and everything is good. Id like to get this figured out if I could. thanks !

 

The coolant float sensor in the expansion tank detects if your coolant is low. They are known to go bad after a while, where they sink even though there is sufficient coolant in the tank. Make sure your coolant level is between min and max lines when cold. If your expansion reservoir is full and your coolant says it’s low, it’s most likely the sensor. In that case you would need to replace the expansion tank.

You can also check your fan by turning on the AC. It should turn on when you put the AC on. Otherwise the fan only turns on when the engine is hot (I don’t recall but I think at around 205 to 210 degrees F).

Boiling shouldn’t happen under 212 F, especially if you are using coolant and have the expansion cap on tight.

 

It should never be boiling coolant.

Bleeding this system is easy. Just fill the header tank, start the car and turn the heater on. Continue to fill it until it is full. Drive it for a few days and check your cold levels and add more as needed.

 

at what temp does the large cooling fan come on ? Mine got to like 205 according to the foxwell tablet I was using for live data and they never came on. I havent heard then in a long long long time. I would know bc when I manually turned them on it for the first time in I want to say years no it sounded like a jet engine but thats only bc it was at 100% I bet. thanks for the reply ill do that. I dont need to mess with that bleed screw in the back left corner (assuming your standing at the front looking at the engine?)

 

I think what you are hearing are air bubbles working there way out. Does the car over heat? Have you drained the coolant?
After fighting this multiple times I finally got a vacuum filler and fixed all that. You need to drain the coolant before pulling a vacuum.
Yes the bleeder screw could be of help. Have you opened it? Did air or fluid come out?

You can check the fan by starting the car cold and turning on the AC. The fan will run on low speed anytime the AC is running. Now it's not easy to see the fan but I can tell with my hand feeling the air flow.
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The fan will not come on with the AC on or off running at ANY speed same with heater. The car hasn't overheated according to the gauge but I do get some steam coming out but I think thats all the hot coolant. The gauge holds normal right dead center, and the car always performs and acts fine. I totally flushed the coolant the other day running 15 gallons of water thru it before it was all totally clear. hoping this would in some way help but it hasn't I just keep having to add more fluid but there isnt any leaking. Youd think at 205 the coolant fan would come on.

 

If the fan is not coming on when the AC is turned on (Compressor kicked in and turning?) then that points to a bad DPS valve that in the AC compressor.
How is the AC? Not a hot time of the year in the US yet so the compressor might not be turning.

Since you ran all the water thru the car could you do a drain and fill using a vacuum filler?

Be careful with the temperature gauge. We really don't have a gauge it's rather more like an indicator. What Jaguar has done is damped the response so the needle stays in the middle over a pretty wide range of temperatures. Plenty of people have over heated their engines and the gauge never moved until it was too late.
Your wise to use a scanner and get the real temperature.
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If the AC is on, the compressor clutch should be engaged at all times, regardless of the exterior temp. Unlike most cars which will engage and disengage the AC compressor at will, our cars have the compressor clutch engaged anytime the AC is on and control the flow of refrigerant using the DPS valve.

 

Just to throw something out there, have you tried replacing the lid to the coolant expansion tank? Mine had a minor crack underneath and it wasn't able to maintain pressure and hence coolant was spilling out the top (bubbles and all). Replaced the lid and all is well.

 

Good point! Do the simple stuff first.
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