How to Bleed a 4.4 Cooling System?


Climbing Nerd
My 2008 LR3 has been running warm since i have the thermostat housing relapsed with an aftermarket one back in December. I sourced a new Thermostat but its self from Atlantic British right before there warehouse closed because of COVID-19. I'm planing to installing it this week, but I have never bleed the cooling system on a 4.4 before. I want to do it a little precise than I use to be on my 4.0s and my 300 TDI where I would just drive it around the block with the cap off the expansion tank until the heater blew hot. Any advise would help. I know this is more of a ********** about the New Defender forum that a Tech on, but I know some people out there know how to do this right.




I replaced hoses and coolant tank (and coolant) a yr or so ago. I found a good writeup on bleeding the system on the disco3 forum. As I recall it mentioned the secret black-arts of bleeding the 4.4.
I followed the process and it's running fine 16 mo later.


Hey @TexasTJ , see the attached link below from AB. You can watch all of it as you are replacing the thermostat or skip to about 6.5min mark going forward. If you google bleeding the 4.4 V8, you will basically get two avenues to go pursue.

The LR Method via the service manual, believe that may be the one @DVD is referencing, and then the more 'eyeball' test per se.

The latter is what AB describes and what I have done in the past with good success. Basically you fill the tank, open the bleed screw and let it fill as much as possible, do that a couple times until the expansion tank level doesn't drop anymore. Screw bleeder back in, start car and let run until the thermostat kicks open (you can leave the exp tank cap off for a bit, but you'll have to put it back on once it warms up obviously), walk to beer fridge and grab a corona your beer of choice, open and take a few sips, walk back to car, turn car off, open the expansion tank lid, and slowly finish your beer. *Repeat approximately 3 times or more depending on beer availability*
The basic premise is that the trapped hot air is going to escape out the highest point and the coolant will more or less backfill into the voids. I also found that just rocking the car back and forth helps speed up the process.

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Sapper Dave

New member
I did the whole coolant system thermostat housing, water pump, and hoses last January (2019). Getting all the air out can be a pain especially if you drain all the coolant out. I'd recommend filling the hoses up leading to the thermostat housing as much as possible prior to connecting them to the housing. This will reduce the amount of air in the system significantly. After that I used the Atlantic British procedure linked by Tyler above and got all the air out without too much fuss and it ran in the middle of the gauge. Abran from Carrs4x4 in Huntington Beach added some BG Super Cool to the system a few months later and the engine has been running a tick cooler than the middle of the gauge since then, including during a cross country move.

Good luck!



Climbing Nerd
I got around to swapping out the thermostat this morning and wow what a difference. The aftermarket one was siting between 211-220. The new Land Rover thermostat is loving 197-200. (May still be a little Air in the system). I’m Happy though! 61F4AEF5-1B15-4226-BE95-25C427E5E306.jpeg


You'll probably have to keep monitoring the coolant level each day or as it cools down and top it off as needed. After a week of driving it should settle in somewhere. The top T-bleeder valve (under the engine cover, near the front of the block) is a good place to dispel air in the system.