1.8 Petrol - Expansion bottle cap probs?

Hi all. Could someone describe the symptoms of an expansion cap failure.
I have a hunch mine is faulty. It seems to be bubbling coolant out of the cap as if the engine was overheating, but the coolant temperature is about normal for a running engine, ie not boiling temp just hot.
Any better ideas, or am I on the right tracks with the expansion cap not holding pressure?

Hmm. my thoughts.

Is the coolant in good condition and is it the correct mix of water and coolant/antifreeze?

Was the system filled to the correct level? I can be a bit higher in the coolant bottle, say a cm. The coolant will rise as the engine heats up - expansion.

Are you confident that your radiator is clean internally and in good serviceable condition?

You said that, "...bubbling coolant out of the cap..." so coolant is pouring / dribbling / dripping / weeping down the outside of the bottle - which word best describes that?

My guess is that you have a faulty cap - a cheap and easy fix, OR a thermostat problem - still a cheap part but awkward to get the existing one out / new one in.

A radiator check would also be advisable.

Have the coolant checked for exhaust gases. The bubbling could be exhaust gases = a blown head gasket not cheap and not so easy either. Blown HG is not a difficult task for the DIYer but the head will need to be checked by a professional.

Keep us posted!

could it be you have air in the system ,take the small hose of the header tank and blow in it ,and this will open the jiggle valve and allow water into the head. also look for cracks around the top of the header tank if it has them then renew, also the proper way of filling the water is to do it when cold on level ground and fill it so it is between the lines on the header tank.

Hi. Thanks for the replies. When I get some daylight I'll check the whole coolant system over properly and for leaks and anything untoward, it has been losing coolant for the last few days and I've been topping up with ready mixed coolant. I'll keep you posted.

If your loosing water and can't see any leaks check your oil to see if it's now become mayo.

Get a block tester off ebay and do a sniffer test on the expansion bottle to see if your getting any gases in the water, the liquid turns from blue to green/yellow if your head gasket as failed.

Yeah. I've owned a few k series engines in the past and experienced the blown head gaskets! This is the first thing I checked: no 'mayonnaise' in the oil or coolant systems, the coolant is normal colour, the heaters blow warm air as normal, the temperature needle rises to middle of gauge and doesn't go up into the red, then after a few miles I check the bottle and the coolant is bubbling out of the cap. If I let it bubble away for too long and I loose too much coolant then the temp starts to rise and I shut the engine off to save it getting overheated. Im sure its coolant loss causing overheating, rather than overheating causing coolant loss.

get a sniff test done

Yeah - sniff test, also is your expansion tank in good order? Mine was cracked and crazed. Around the top and couldn't hold pressure. A replacement tank is a cheap option.

A favorite leaking place is at the back under the inlet manifold. Also it can leak into the engine from the inlet manifold.

But if it is bubbling there's further investigation required.

Hi. I changed the inlet manifold gasket myself a few months back, I had coolant leaking from the manifold, she's been running fine since then, until this week.
Think I'll invest in a block testing kit, just been watching vids on youtube to get an idea of how they work.
Its finding the time to get outside and check it out, what with it starting ti get dark early and me working crazy amounts of overtime recently!

could it be your thermostat is stuck closed

When the engine is cold you have pressure in the cooling system ???
Remove the cap from the expansion tank and acceleration and smell, if it smells like exhaust gas could be cracked cylinder head or cylinder head gasket blown
thermostat is easy to check, when he opened the radiator heats up,fans should not start before the thermostat to open

Liner dropped?

Start cheap, try a new cap.

So to recap [ not sorry for that pun]

• check coolant at correct level and new[ish]
• sniffer test of coolant,
• if no gases, have a careful look at the neck area of the coolant bottle, replace if necessary and fit a new cap.

If there's still a problem consider a thermostat problem - replace if necessary.

However, if gases are in the coolant then get ready to replace the HG.
If you have to remove the head then I would suggest the following:

• carefully check head height - still within spec'?
• check head for: cracks, hardness / porousity, warping... skim if required
• carefully check liner heights - that may help in your selection of HG - if all are above the head and fairly even then fit a reputable MLS HG, if they are low [ish] or level then you may be best with a Payen BW750 very much like the original elastopolimer gasket.
• If the liners have sunk below the block face then you can fit shims to the liners and reinstall them. But that's another story!

The coolant apertures in the head [ inlet & exhaust side] benefit from being cleaned up a bit as they are very likely poorly cleared at manufacturer - allows greater coolant flow.
May as well replace w'pump, tensioner & cambelt [ unless very new].
To finish it off have that radiator checked / cleaned.

Ok guys, my work is done for the week so I've had some free time to get my head under the bonnet here's what I've found so far...
Started by degreasing, cleaning and drying all round the head, block, hoses everywhere nice and clean so I could spot any leaks etc.
It's worth mentioning that the coolant level hasn't dropped since I last looked at the car, I know this can happen with IMG failure loosing coolant when engine is cold.
So, with this done I ran the engine, with bottle cap REMOVED, heaters switched on, checked system is bled properly of air, and watched carefully for leaks using a torch and mirror to see behind & under everwhere that a leak might occur.
I ran the engine at idle NO REVVING for a good 15 - 20mins, no sign of any visible extrrnal leaks, temp gauge rose to middle and stayed there, the two hoses to the heater matrix were good and hot, heaters blowing hot air, no damp carpets in footwells. The hose from engine to radiator top was hot to touch, but hose from bottom of radiator to the metal pipe with bleed screw never got warm at all, in fact it stayed cold and whenever I checked by opening the bleed the coolant was cold here. Never got warm during duration of the test, rad never warmed up and fans never kicked-in (I know the fans do work because they did the other day when the car started overheating).
At no point during the test did I see the coolant bubbling or any funny smells or gases from bottle, (will get a proper block test kit).
My initial thoughts are that at idle the engine seems to behave normally, so bit worried that its something internal that only occurs when the engine is working hard, hopefully this isn't the case. Does anything I have described here give anyone any inspiration? Should the pipe from bottom of radiator stay cold, or could this mean my thermostat isn't opening?
All help and advice us appreciated guys. Thanks.

Fr33LandER said:

Ok guys, my work is done for the week so I've had some free time to get my head under the bonnet here's what I've found so far...
Started by degreasing, cleaning and drying all round the head, block, hoses everywhere nice and clean so I could spot any leaks etc.
It's worth mentioning that the coolant level hasn't dropped since I last looked at the car, I know this can happen with IMG failure loosing coolant when engine is cold.
So, with this done I ran the engine, with bottle cap REMOVED, heaters switched on, checked system is bled properly of air, and watched carefully for leaks using a torch and mirror to see behind & under everwhere that a leak might occur.
I ran the engine at idle NO REVVING for a good 15 - 20mins, no sign of any visible extrrnal leaks, temp gauge rose to middle and stayed there, the two hoses to the heater matrix were good and hot, heaters blowing hot air, no damp carpets in footwells. The hose from engine to radiator top was hot to touch, but hose from bottom of radiator to the metal pipe with bleed screw never got warm at all, in fact it stayed cold and whenever I checked by opening the bleed the coolant was cold here. Never got warm during duration of the test, rad never warmed up and fans never kicked-in (I know the fans do work because they did the other day when the car started overheating).
At no point during the test did I see the coolant bubbling or any funny smells or gases from bottle, (will get a proper block test kit).
My initial thoughts are that at idle the engine seems to behave normally, so bit worried that its something internal that only occurs when the engine is working hard, hopefully this isn't the case. Does anything I have described here give anyone any inspiration? Should the pipe from bottom of radiator stay cold, or could this mean my thermostat isn't opening?
All help and advice us appreciated guys. Thanks.

Click to expand...

If it remains cold the thermostat is broken

+1

Ok, thank you all so much. New thermostat coming up then!
I will probably buy the remote thermostat kit which will help protect my HG in the future and also make future thermostat checks/changes a lot easier. I just picked up a brand new genuine thermostat bypass plate from eBay for £4.50 - bargain, just need the Bearmach kit now. Oh and what thermostat part number do I buy to go with this kit?

Fr33LandER said:

Ok, thank you all so much. New thermostat coming up then!
I will probably buy the remote thermostat kit which will help protect my HG in the future and also make future thermostat checks/changes a lot easier. I just picked up a brand new genuine thermostat bypass plate from eBay for £4.50 - bargain, just need the Bearmach kit now. Oh and what thermostat part number do I buy to go with this kit?

Click to expand...

Just incase you didn't know, you can buy them complete on e bay...like this one
Land Rover Freelander 1.8 thermostat Upgrade Head Gasket Saver | eBay

Hi I have just about the same problem
I replaced the engine in the FL about a month ago and did the cambelt, tensioner and water pump also did the expansion tank and cap. Last sat when I pulled up at home saw water dripping from it, popped the bonnet saw the expansion tank was empty and thought HGF though the temp gauge was never was above halfway. Today finally found time to have a look at it. Filled and bled it so I could get it to work to have a better look.Found no water in the oil or vice versa all pipes warmed up heater working properly left idling for ages water flowing constantly into header tank no pressure behind cap when taken off which I thought odd. Did a few short runs 3 miles or so no problems,, did a 10 mile run up and down dual carriageway and when I got back the header tank was full with signs the cap was venting,; shut the engine off and the tank level dropped to normal. Did another 3 mile run level stayed normal took cap off still no pressure behind it, put cap back on left idling for 15 mins tank suddenly filled to top fan kicked in level dropped back to normal, temp gauge always normal no obvious water leaks. Anyone heard of a new cap failing or is that just wish full thinking before I go down the head gasket route
Any comments welcome