Range Rover Classic Loosing coolant -not to the engine !

I seem to be plagued with issues accross both my landrovers at present maybe they have decide to take a xmas break !!

My 93 RR classic has started to lose coolant when hot from the coolant bottle i.e a short say 10KM trip is fine but on a longer trip when all is fine until you stop at which time the coolant overfills the expansion bottle and proceeds to exit under the coollant overflow bottle cap to the extent it emptys the bottle !!!

On shorter trips this does not happen at all.

I have so far replaced the expansion bottle cap with a new Bearmach one to ensure it is sealing correctly etc but the problem still exists. I wonder whether the engine is just getting to hot although the temperature guage stays in the middle the viscous fan is tighter when the engine is hot but it can still be turned so it doesnt fully lock up ( not sure if they are ever meant to as my Disco 2 V8 never completely locks).

Could it be the thermostat ??

Any and all ideas appreciated, otherwise engine runs fine no coolant visible in oil and wasnt using coolant prior to this.

Based on personal experience, try this. Following a run let the car stand overnight (so that it is completely cold) then remove the pressure cap. More than the slightest pressure release at that time would point to a head-gasket problem.

norseman said:

Based on personal experience, try this. Following a run let the car stand overnight (so that it is completely cold) then remove the pressure cap. More than the slightest pressure release at that time would point to a head-gasket problem.

Click to expand...

Not necessarly...

Had similar on the L322....turned out to be an air lock!

The classic has a specific filling procedure to prevent air locks using the filling tower to the left of the plenum to prevent air locks (looking to the engine bay). when you replaced the expansion bottle did you replace the coolant ?

Go through the correct fill procedure again to ensure no air locks. Rune her up to warm with rad cap off when warm top up rad expansion bottle and fill tower.
Of she throws the coolant out again you head gaskets are suspect.

On one of my rrc when the head went you cpould see bubbles coming through the expansion bottle when running

Will try the run and leave overnight test otday. Didnt change coollant just the resevoir cap, have changed coolant a few times over the years and like my disco always bled the system as per rave.
thks

Checked the overflow bottle this morning no pressure at all on removing cap. Also ran the motor and no bubbles rising intro the bottle while running motor. I also topped the bottle right up and what did happen is coolant overflowed the bottle when the motor was running. I could changew the thermostat but it would only be an issue if it wasnt opening and motor was overheating which it does not seem to be doing.. Am a bit lost as to what to try...

I take it that it was the expansion bottle you topped right up. These are not meant to be full so will overflow when hot. Check the level when cold.

does the hearer work?
if blocked will cause major issues