So, came back from work, a 45km commute in various traffic conditions. Nothing happened. Left home again, to run some errands another 20 +20 km half of which in traffic and half on the motorway. Came home and opened the bonnet to find coolant spilled. It seems as if it was a single release event. But the cap kept weeping slowly and after a few minutes from shutdown a small quantity of coolant has been expelled on the reservoir mounting bracket...
I'll fit a second hand cap I have lying around to see how that will behave tomorrow. But it seems like either the 40-50km runs are not enough to build up exvessive pressure, or something opens up, pressurizes the system and then returns to the initial state? 🤷‍♂️The car hasn't overheated. So I guess the coolant loss through the cap wasn't enough to cause further problems.
But it makes me wonder, because I've seen headgaskets go on the freelander and whenever the expansion tank got pressurized, there would be a continuous loss of coolant not just a burp... Anyway, I'll know in a day.

Meanwhile, I opened the cap to find air / gas trapped again. About a liter of lukewarm coolant and froth escaped the tank. I refilled to the neck on purpose then revved the engine as seen on the video. I did not see bubbles emerging, not significant at least. This video was taken near operating temperature. When I closed cap, pressure and temp in top hose quickly built up and the steady stream of coolant from bleeder screw was replaced by frothy coolant but I assume that's supposed to be happening as coolant warms up?? And that's why system is bled cold?

https://vimeo.com/661020271


And another one, even closer to operating temp

https://vimeo.com/661023949

Tomorrow I'll bleed the system cold. Placed an old, used cap to see how it goes and I'm going to pick up a new cap with some extra coolant.

I can see why your having issues you are over filling and not bleeding correctly

https://www.fullfatrr.com/gallery/albums/u...ooling.JPG

Yes, I'm intentionally overfilling to see if bubbles would emerge from the small feeding hose opening. Please note that I haven't bled the system on the video. My intention was to detect bubbles from a possible hg failure.

Now, is it normal for the coolant to become frothy as it comes to temp?

Squeeze all the hoses to get any trapped air out the smallest amount trapped in the system will cause issues. Remove the bleed screw and let any trapped air out until you have a constant stream of coolant comming out, replace the bleed screw then check for coolant trickling into the expansion bottle via the small hole if you have a constant stream replace the expansion bottle cap IF you don't you still have trapped air.

Hi, I have the same engine as yours
To bleed the engine, I remove the top hose from the radiator, remove the bleed pipe from the radiator, hold the top hose up higher than the radiator, block the top radiator pipe (the one the top hose fits on to).
fill the tank with coolant.
You should see the top hose fill with coolant and coolant flow from the bleed nipple on the top of the radiator, if you see this, refit the hoses, finish bleeding it from the bleeder, you are done.
Some times an air lock will stop the coolant flowing through and the coolant just stays in the tank.
If this happens, block the bleed pipe with your finger and put your mouth over the filler on the tank and blow hard, this will clear the air lock, might have to do it twice depending how hard you can blow.
I have been reading your posts, and keep thinking about the thermostat.
I think it could be dodgy, intermittent.
I fitted a BMW thermostat that was 80+ on opening.
I have a new thermostat for this engine, 105deg or what ever it is, never opened the box, which you can have very cheap.
I bought it, then decided to go for the lower temp one
Good luck RR 2005 4.4 petrol
Any spelling mistakes are the fault of spellchecker
Previous MG J2, CITROEN light 15 x 2 gone unfortunately
Present MERC 180e, RANGE ROVER L322, JAGUAR XJS, MERC 280SE, MG F, JAGUAR S-Type 6v 2003, jaguar s-type 8v 2004, Ford Cougar

Thank you so much.

I do get an occasional "Electric Thermostat circuit fault" which seems to be coming back every time. I have checked and cleaned the plug which is in good shape. I have driven with the IID recording data, seeing nothing to suggest a problem. The Thermostat is also about 11 months or 20K km old and it's a Behr 105C. I'll see if I can change it today.
I really never paid much attention to the thermostat circuit error message and thanks for pointing out the stat. If the plugs and wiring are okay, which they are, then perhaps something could be gradually failing within the stat?
Nothing to lose, really, by changing the thermostat and cap right away. I'll change that top hose too, while at it.

Last edited by vs322 on 30th Dec 2021 6:34am. Edited 1 time in total

So, I checked the level and was at the bottom of the expansion tank, as expected. Upper hose was a tiny little bit sucked in. Topped up to "Cold" and started the motor. I was greeted by a steady stream of coolant through the return hole in the neck. Massaged top hose a bit a few times and each time the flow would be briefly interrupted then resume solid. Bled through the screw as well, although probably unnecessarily, and still no bubbles emerged.
Fitted back the old, used cap I had put on last night and bled once more from the screw, near operating temperature.
Heater has been blowing nice and warm almost from the get go. Temp needle climbed to within a cat's whisker beyond center, as it has always been since I've had the car. Took her for a spin and she runs as if nothing's wrong.
Parked on the driveway, popped the bonnet and no sign of coolant around the cap. Top hose is hot to the touch and firmly pressurized (but not solid), bottom hose is lukewarm, at best.

I'll drop by ex-stealers to see if they have a new cap and thermostat to sell me, then drop by my indy and try to convince him to fit them, along with the top hose we've already got.
At the very least I'll be replacing the cap today and get my GAP back from him and have some real time temp recordings on my way home.

Thanks everyone for your kind help so far! I'll keep you posted.

PS. I'm still going to that garage tomorrow, regardless. I'm using this car daily and on hunting trips. So, being stranded in some remote mountainous area or in the wetlands is absolutely out of the question.

Still out shopping, picked new cap (not fitted yet) waiting on the thermostat...

Meantime, here's some road data with the second hand cap



I don't see any overheating going on and the thermostat surely opens at around 105C.

Electric thermostat circuit fault IS present, though.

I don't seem to be able to make it and change stat and hose today, I'll combine with coolant flush tomorrow most probably.

Okay, we might be on to something here, gentlemen.

Did a couple supply runs and got stuck in traffic. With the IID on live values, coolant and rad temperatures looked just fine. Heat exchange began to take place whenever the coolant temp reached 106C and coolant never reached above 109C. So we can rule out any overheating. The temp gauge seems to corroborate that.

Top radiator hose has been firm and hot when at temp but no leaking has been noticed fromt the expansion tank cap.

Now, after 2 hours parked, top hose is lukewarm and can be squeezed. Remember, it used to be firm even overnight.

Early evening I'll replace this cap with the brand new one and keep this one as a spare.

me if it's the bloody cap after all!

Old cap off, new cap on. Barely any leftover pressure in the system after less than 4 hours of cooling down. No funny smell, either!

Took apart the (likely) offending cap and found the plastic to be very brittle

Click image to enlarge

Wrapping this painful story up and fairly certain I'm not speaking too soon:

It all...boiled down to a faulty cap!

It had been pressurizing the system, cycle after cycle for quite a while. And failed to equalize pressure while cooling down. Thus resulting in more pressure being built up every day. As the valve continued to deteriorate, the symptoms became more pronounced. And each time I opened the cap, they were briefly masked, so this habit of checking every other day kept the system going during the hour long commute to / from work.

Now I've changed the cap, changed the upper radiator hose, changed thermostat. Electric thermostat circuit fault code disappeared as well.

Both thermostat and cap were newish. Although, thinking back, the bloody cap was delivered in an open packaging. Needless to say I'm never buying anything from that place again.

For the collective benefit of this community, my recent ordeal serves as a prime example of how important it is to research, ask, observe and make sense of what you're facing.

A series of coincidental events led almost everyone I asked advice from, myself included, to consider with a fair degree of certainty a head gasket failure or worse. Please refer to my other posts on spark plugs; it gets interesting.

I visited several garages all suggesting the same. Got various quotes all over the place, from 4K up to, yes, 12K euros!!! For HG, vanos and timing chains job.
I've decided to purchase all the major bits myself when the time comes for such an undertaking and have a reputable garage fit them under the condition they would accept my presence as an observer.

I take this opportunity to thank, from the bottom of my heart, all those who took the time and trouble to post their views and suggestions of which I'm grateful. This site has been an incredible guide to my ownership experience.

Thanks again and much love to everybody in here; my gratitude to Admin and mods. Wishing you all, a very happy and healthy new year!

vs

Told ya

Enjoy the car, and have a worry free 2022

You were right all along

Happy 2022!