Water coolant getting pressurised

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lespingu

Member
Posts
19
Hi all just a wee question!! Have a 2 litre diesel freelander T reg love it nothing better haha, have been told conflicting things about the reason for my freelander having a pressurised coolant system!!!?
This engine has not been started for 3 years due to being stood up for a leaking radiator (new one fitted ) illness etc etc ,
New filter fitted , bled fuel through with pump, started second turn off key
Starts first time every time wither it stands for 2 or 3 days starts straight away
Now coolant is pressurised but doesn’t blow water out off expansion tank ??? Have had it ticking over for 2 hours and no water blowing out ?? Told CH gasket?? Exhaust manifold gasket ?? What do you boys think is the most likely?? is it possible for the exhaust manifold gasket to cause pressure in the coolant?? Thanks for your help in advance peeps
 
Sorry but am I missing something here, all coolant systems are pressurised with a rad cap pressure of approx 15psi, the only non pressure non water system I know of is Evans waterless system which is anti corrosive and non pressurised system as it has a much higher boiling ceiling than water but cost around £100 to do a system but can be left in for life of vehicle so a pipework should be checked before hand as liquid dear
 
As @keithcanfixit has already said any engine filled with a water/anti-freeze mix will pressurise when it gets hot. The actual pressure is set by the radiator or expansion bottle cap. The theory behind it being that water under pressure will boil at a slightly higher temperature. Replacement expansion caps are fairly cheap and I would recommend that you do change it anyway.
The next consideration is do the main coolant hoses all get hot or does the top hose get very hard, or over-pressurised?
You say that no coolant is being blown off, so that would suggest that things are looking OK. Loss of coolant through the expansion tank cap can usually be traced to either an air lock, or over-pressurising and that can often be traced to a blown cylinder head gasket. The exhaust manifold gasket isn't likely to be involved in coolant problems. Loss of coolant without being blown off would suggest a leak somewhere else in the system.
2 hours at tick-over isn't really a good test, you really need to get the engine working under a load, get it out on the road as soon as you can get it legal.
 
brian47 said:
As @keithcanfixit has already said any engine filled with a water/anti-freeze mix will pressurise when it gets hot. The actual pressure is set by the radiator or expansion bottle cap. The theory behind it being that water under pressure will boil at a slightly higher temperature. Replacement expansion caps are fairly cheap and I would recommend that you do change it anyway.
The next consideration is do the main coolant hoses all get hot or does the top hose get very hard, or over-pressurised?
You say that no coolant is being blown off, so that would suggest that things are looking OK. Loss of coolant through the expansion tank cap can usually be traced to either an air lock, or over-pressurising and that can often be traced to a blown cylinder head gasket. The exhaust manifold gasket isn't likely to be involved in coolant problems. Loss of coolant without being blown off would suggest a leak somewhere else in the system.
2 hours at tick-over isn't really a good test, you really need to get the engine working under a load, get it out on the road as soon as you can get it legal.
Click to expand...
brian47 said:
As @keithcanfixit has already said any engine filled with a water/anti-freeze mix will pressurise when it gets hot. The actual pressure is set by the radiator or expansion bottle cap. The theory behind it being that water under pressure will boil at a slightly higher temperature. Replacement expansion caps are fairly cheap and I would recommend that you do change it anyway.
The next consideration is do the main coolant hoses all get hot or does the top hose get very hard, or over-pressurised?
You say that no coolant is being blown off, so that would suggest that things are looking OK. Loss of coolant through the expansion tank cap can usually be traced to either an air lock, or over-pressurising and that can often be traced to a blown cylinder head gasket. The exhaust manifold gasket isn't likely to be involved in coolant problems. Loss of coolant without being blown off would suggest a leak somewhere else in the system.
2 hours at tick-over isn't really a good test, you really need to get the engine working under a load, get it out on the road as soon as you can get it legal.
Click to expand...
brian47 said:
As @keithcanfixit has already said any engine filled with a water/anti-freeze mix will pressurise when it gets hot. The actual pressure is set by the radiator or expansion bottle cap. The theory behind it being that water under pressure will boil at a slightly higher temperature. Replacement expansion caps are fairly cheap and I would recommend that you do change it anyway.
The next consideration is do the main coolant hoses all get hot or does the top hose get very hard, or over-pressurised?
You say that no coolant is being blown off, so that would suggest that things are looking OK. Loss of coolant through the expansion tank cap can usually be traced to either an air lock, or over-pressurising and that can often be traced to a blown cylinder head gasket. The exhaust manifold gasket isn't likely to be involved in coolant problems. Loss of coolant without being blown off would suggest a leak somewhere else in the system.
2 hours at tick-over isn't really a good test, you really need to get the engine working under a load, get it out on the road as soon as you can get it legal.
Click to expand...
Cheers brian47 all pipes hot,top pipe hard !! Can’t find any leaks water goes down in expansion tank when top pipe becomes hard , when you slowly slacken expansion tank lid releasing pressure water comes back in !!!
 
keithcanfixit said:
Sorry but am I missing something here, all coolant systems are pressurised with a rad cap pressure of approx 15psi, the only non pressure non water system I know of is Evans waterless system which is anti corrosive and non pressurised system as it has a much higher boiling ceiling than water but cost around £100 to do a system but can be left in for life of vehicle so a pipework should be checked before hand as liquid dear
Click to expand...
Thanks Keith for your reply but think Brian47 understood what I was meaning ! As we all know most radiators are pressurised! as normal , but when most people say my water coolant is pressurising it means it’s pressurising a bit more than normal ! My mistake for not being more expletive about this problem but thanks for your help anyway bud
 
lespingu said:
Thanks Keith for your reply but think Brian47 understood what I was meaning ! As we all know most radiators are pressurised! as normal , but when most people say my water coolant is pressurising it means it’s pressurising a bit more than normal ! My mistake for not being more expletive about this problem but thanks for your help anyway bud
Click to expand...

How do you know it's more pressurised than normal? Is it venting out the cap?

Your disappearing coolant says "system needs bleeding" to me. ;)
 
Nodge68 said:
How do you know it's more pressurised than normal? Is it venting out the cap?

Your disappearing coolant says "system needs bleeding" to me. ;)
Click to expand...
Not venting Nodge68! so will try and bleed it all again as anything is worth a try cheers bud will let you know how I get on as can’t manage till Monday night
 
lespingu said:
Not venting Nodge68! so will try and bleed it all again as anything is worth a try cheers bud will let you know how I get on as can’t manage till Monday night
Click to expand...
Hi Nodge as you can see never made Monday now Thursday lol but Rome wasn’t built in a day ‍♂️ well I think I bleed it all properly! Top hose is hot bottom hose is cold , but new rad would cause this I think pressure is quite severe hoses get really solid ! And water disappears! When you slowly unscrew expansion tank top water comes back in and obviously pressure is released ?? This is a 2.litre diesel mk1 I’m thinking along the lines off chg but it starts so easy! And ticks over so sweetly never missing a beat!!! I’m so annoyed at this now , got a message saying check my inlet manifold is this possible Nodge I’m no mechanic just a self taught d.i.y fella any help please ‍♂️‍♂️‍♂️
 
If the coolant disappears then reappears when the pressure is released there is still air in the system.
 
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