Is it normal for the radiator fan to run for about 20/30 seconds after turning off the car? I just finished replacing thermostat and cooling pipes This is my first summer with the car and we are going through a heatwave

 

This can be quite normal since the fan speed is a function of engine coolant temperature, transmission fluid temperature and A/C system pressure. The fan can run for up to 4 minutes after the engine is shut off.

 

Mine does this too man, for about the same amount of time. I replaced the cross over pipes with metal ones as well. I don’t remember it doing this before with the old plastic pipes. My theory is that the metal pipes may create more heat under the hood and they may take a bit longer to cool off. As such, we hear the fan after the vehicle shuts off. This is just a guess though.

 

Yeah very strange I thought if anything the car would be running cooler looks like its running warmer now
I hope its not the new thermostat I installed

 

better get your thermostat checked if the fans run after shut down

 

The first thing to do is to start monitoring the engine coolant temperature. This can easily be done through the diagnostic connector with an inexpensive device. You can then compare how your cooling system is doing compared to the information in the Service Manual. THEN you can start checking items which actually influence the performance of your cooling system----thermostat. fan, pressure cap on expansion tank etc etc

For $30 or so you can have on line real time monitoring of whatever PIDs are monitored by the PCM. I usually watch engine oil temperature, engine oil temperature and alternator output as shown below. There are all kinds of other devices available including bluetooth to your cell fone.

 

Almost any combustion engine vehicle with engine managned system controlled FAN (since early -90:s) will run the fan after engine shutdown in summertime when temps are higher.
Nothing new or weird on that.
It can also happen that the fan will start running for few moments after shut down of the vehicle. This comes from that the water circulation stops on cooling system and hot parts start to warm water what are now stop. Water heats up and temp sensor reading increase and ECU start the fan. (as we know there are XXmin shutdown period on modern vehicle systems)

 

Good idea what is that thing called? I will set mine to monitor the coolant temp

 

I use and recommend the custom PID pack Cambo built for Torque Pro. Very cheap and easy to use.
Take a look at this old but detailed thread by Cambo who wrote all this. I have it installed on a $80 used Android tablet for the larger screen.
Torque Pro Custom PID Pack
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The device is an AUTOOL X60. Plugs into the diagnostic connector. Powers up with ignition and powers down with ignition off. I have had on my 2012 XF for almost 4 years and I use it all the time. Currently on ebay.ca for $52 Cdn, Maybe cheaper on Chinese sites.

 

I do not hear the fan running anymore I don't hear the fan anymore at all even after getting off the highway and idling for 5 mins
I think the problem was not enough coolant in the system I have topped up the coolant 3 times from min mark to max mark close to 5 liters now 4 liters at first another liter from top ups after replacing water pump, ,thermosets and upgrading to aluminum pipes
I pressure checked the system for 5 mins it does hold pressure I do not see any leaks Where all this coolant is going I do not know I did not even drain the radiator

 

Well it's probably magic! Just as a matter of interest what happens to the coolant level in the coolant expansion tank when you apply the the 15 psi pressure for your pressure test? Anything more than 1/2 inch suggests you may have air in the cooling system.

 

The level in the expansion tank does go down about 1/2inch maybe a bit more from max mark to min mark
I left it at 15psi for 5 mins the gauge did not move

 

Yes you had trapped air and apparently quite a bit!
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Why do you monitor your oil temp??

 

1 Because suddenly rising oil temperature can be an early indicator of coolant loss. 2 Or possible lubrication problems. My 5.0L NA V8 usually has an oil temperature 30-35F higher than the engine coolant temperature.

 

[QUOTE=Six Rotors;2764365]1 Because suddenly rising oil temperature can be an early indicator of coolant loss. 2 Or possible lubrication problems. My 5.0L NA V8 usually has an oil temperature 30-35F higher than the engine coolant temperature.[/QUOT

It is better to monitor the oil temp over the coolant temp?

 

In my younger days I ran Mazda RX-7 Turbo IIs and a RX-7 Twin Turbo. These rotary engines rejected almost 50% of the engine heat through the engine oil and naturally I watched engine oil temperatures closely. Both cars had massive oil/air coolers in the front air scoops.
I really have no idea how much heat is rejected through the engine oil in my 5.0 NA but there must be a reason why Jaguar chose to have so much oil in the engine. I also read a number of stories on the Forum of people loosing engine coolant without any warning. So it is a no brainer to monitor BOTH engine coolant and oil temperature and it is so easy to do.