Jaguarxj8 1999 3.2.water overheats after about half a mile.bubbling out of the expansion tank.any ideas please.

It sounds like either a blocked radiator or cylinder head gasket problem

There's trapped air in the cooling system.

• You need to remove the bleeder screw on top of the radiator when adding water to the expansion tank.
• With the engine running, pour water into the expansion tank till you see air go out through the bleeder screw's hole.
• Just keep adding water until no more air bubbles come out then just put the screw back in place.
• Then fill the expansion tank to it's normal level/line.

!st replace the radiator cap. It is possible you have a blown head gasket. Does it run rough when 1st started then clear up?

take it to someone else, have them pressure test the system, mine did that and i was into 1200 bucks for new heads, two years ater since i drove it like you have been i developed a misfire , the coolant leaks into the system and is like sand paper on cylinders bearings, clue was the expansion tank bubbling and vibrating after ya turn off the car, good luck i hate this car

Did you replace the thermostat? Does it overheat? You could have just over filled it. Just run it a couple of days and watch the heat gauge. If it keeps bubbling out of the expansion tank I would recheck the torque on the head bolts. You will have to loosen them up and retorque them in sequence, from the center back and forth out to the sides.

replace your coolant reservior cap; the rubber ring has become brittle and "steams" the coolant out as you drive

If your oil is milky it is a blown head gasket or worse a warped head.

Might be worth changing water expansion tank cap these can lose water under pressure

hi it sounds like your headgaskets blown you need to take your rad cap off fill with water start the engine see if you see any bubbles in the water or if the water blows straight out its a good indication the headgaskets gone the thing on the right hand side is the expansion tank overflow if this blows water out even when cold the headgaskets gone if you see no bubbles in the water change your thermostat the two fans on the rad have nothing to do with your a/c if that doesn,t work may need pressurising yates210456

nooooo.
that's the problem
yes, you have to take the coolant filling cap off " expansion tank cap "
turn your car on for at least an hour
the bmw line has a very bad problem wich is " bubbles " inside your water system
you have to have your car inclined and running without the cap so he can bleed all the bubbles out.
sorry you spent all that money but after you replaced the radiator all you had to do was that, to get rid of bubbles.

so, do this. park your car on an incline position, engine up.
remove the cap. let it run for at least an hour.
refill as needed " coolant "
do that the following morning and for last refill the collant as needed.
problem should desapear.
hope this helps