Freelander 1 G4 coolant loss - solved

So, long motorway run. 1.8k running very well.
Stopped for a drink at services and as I stopped the engine fan ran. Not heard it before. Decided to check coolant. Header tank empty!!!!

Oil level normal. Took about 3/4 litre of hot water from the gents to bring back up.
Damp around header cap. Only thing I had was some clingfilm. Put 4 layers over tank and screwed top on. Many checks and 40mph on way home. All good. Top feels a bad fit so changing the tank and cap. Hope I have been lucky and caught it in time. Temp gauge never left normal. Need a low level indicator me thinks.

I installed a float switch to my V6, which sounded a buzzer when the coolant dropped be minimum.

Just ordered a small capacitive water low level sensor to fix on the outside of the coolant bottle.
Report back if it works !!
Hoping I caught it in time.Worth doing a compression test??

I'd have thought the only thing cling film could do would be to make things worse.

The coolant will expand as it warms up and needs to escape through the cap vent.

I'd presume the cling film will break, but if it doesn't, that pressure will need to be relieved somewhere else.

The cap should be pressure tested, but are there cracks around the top on the tank?

andyfreelandy said:

Worth doing a compression test??

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If it drove X number of miles home, then that's proof enough that it's ok.

GrumpyGel said:

I'd have thought the only thing cling film could do would be to make things worse.

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The cap appeared to be leaking and so I used what I had to get home. The film would have blown but it sealed the washer and thread sufficiently to do a steady drive 80 miles home.
Coolant level is fine when home. Top feels decidedly dodgy and turns past the click and then loosens. No cracks that I can see but will change tank and cap and fit a level sensor.

Replaced cap and took for short run. About 5 miles.
Stopped, cap venting and water boiling.
Water level remains fine, apart from the loss through the vent, until you switch the engine off.
Then, the header tank empties before your eyes!!
No idea where the water is going. Car runs fine, no increase or contamination of oil. No trace in cam cover.
Doesn't appear good news.
Anyone had a head gasket go where the water just disappears!!!
I expected the bore to lock after watching it empty, but no, perfect running.
Can't think that it is anything other than head gasket now.

Have you checked the sump? If it's internally haemoraging that much water, I can only think cracked liner / unseated liner and the water is finding its way into the sump?

Thanks, it is weird. Have checked oil level and unchanged and uncontaminated.
Engine runs perfectly.

I have now repeated the failure a few times.
Top up with water. Bleed system. Tick over all good. Left to open the stat which is an external one with the new pipes.
No problem, ticks over fine, no water loss.
Take out for short run, steam from header cap. Water boiling. I know it is boiling as it continues when you turn the engine off so not pressure from firing.
Turn engine off and half a header of water just gets sucked into somewhere!!!

Only damp patch I can see is on top of gearbox at rear of engine, but no wet pipes or inlet manifold.
Doing my head is this!!

Did a fluid sniff test and all clear at idle.
My theory is still that there is an opening in the coolant system somewhere allowing the water to boil, but where is unknown.
Looks like it's off the road for now.

Does the water return? It sounds like it could be airlocked. Have you checked the juggle valve in the inlet manifold is free to pass air? Some people remove the jiggle valve completely, but the inlet manifold needs to come off for that operation.

Not seen the water come back again.
I'm thinking air lock, inlet manifold internal leak, thermostat housing, water pump leak.

Just a spot of water at rear of engine on the gearbox, can't see where it has come from.
Really aggressive when boiling, sounds like it going to take off!!
It has had a haed gasket done before, wonder if the jiggle has got crud in it?
Easier to whip the inlet off and change the gasket and do the valve than a head job to start with.
There is some crud in the header tank but I'm hoping it is from a past failure.

you really shouldn't be putting just water in you should be using a good quality coolant , is there any damp on passenger floor well the only other thing could be a leak at the back of the engine going straight onto the exhaust burning of so there would be either no wet patch or very little

Dbest43 said:

you really shouldn't be putting just water in you should be using a good quality coolant

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Why?

Water hits boiling point quicker than coolant and leaves a residue in the working components coolants work at minus 25 degrees and plus 160 degrees and keeps the engine well maintained and therefore never reaching boiling

Have a look under the rubber mat in the passenger footwell.

Dbest43 said:

Water hits boiling point quicker than coolant and leaves a residue in the working components coolants work at minus 25 degrees and plus 160 degrees and keeps the engine well maintained and therefore never reaching boiling

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In normal circumstances, yes the system should be OAT coolant at 50% concentration, but for investigation of a coolant loss issue, water is just fine.
The normal operating temperature of the K series is under 100°C, and the coolant is, or should be under pressure, which is what increases the boiling point considerably.
Additional chemicals simply make a sticky mess, cost a lot the throw on the floor, and pollute the environment where it's spilled.

GrumpyGel said:

Have a look under the rubber mat in the passenger footwell.

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Thanks for all the suggestions. Sadly not visible anywhere!!
A look at the plugs and a compression test next. Can't believe it would run as well with hgf but if I can eliminate it then it has to be inlet manifold leak or air lock.
The weird bit is that it drove for 80 miles with no loss (with my cling film mod of course!), then when you turn the engine off it is like it is having a cold beer!! Glug, Glug......

I'd start with the thermostat and header tank

andyfreelandy said:

The weird bit is that it drove for 80 miles with no loss (with my cling film mod of course!), then when you turn the engine off it is like it is having a cold beer!! Glug, Glug......

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Does it have the PRT thermostat, or the pump mounted stat?
Have you opened the bleed points to expel any air in the system?