pressurings cooling system

[VL Berlina 5speed]

this is a question not based on a commodore, its the tata ute

the radiator seems to be presurising and blowing air into the overflow bottle
the coolant is droping in the radiator but the it isnt droping in the overflow

now only way i can think to get pressure in the coolant system is a cracked head (blowing engine compresion in)
but the oil cap isnt milky or the exhaust isnt shooting steam

any ideas?
its turbo diesil

[commsirac]

How do you know its just blowing air into the overflow?
What happens when the coolant is filled to the top of the radiator, does it push coolant into the overflow in this condition.

Most often, the radiator level can drop due to the connections between the coolant reservior and the radiator having a leak. The expulsion of coolant typically takes place quite quickly and violently, so even if there are weak points in the connection most of the overflow ends up in the coolant reservior. The opposite isnt the case when the system draws coolant back from the overflow when cooling down. The difference in pressure is only slight and air can easily seep in rather than coolant being forced into the radiator by atmospheric pressure.

[VL Berlina 5speed]

the over flow pipe isnt blowing water out as there is no brown water mud on the end of the new pipe

when you stop and turn the engine off you can hear it bubbling away really fast for a minute into the overflow

before a drive this morning the radiator was full to the top, over flow was on max,
now its down a inch and half and still on max for overflow


no temp guage as it doesnt work and the system was flushed and filled a month ago as we thought it was blocked

[VrWagz1]

could be a small leak somwhere, had a similar issue a while back, was a old clamp on the bottom hose, was just weeping and dropping pressure out of the system, there for not sucking water back in as the car cooled.
Is the hose going to the overflow bottle in good condition and not crimped.

[VL Berlina 5speed]

cant find any leaks and the pipe running from over flow to the radiator is fine, no crimps kinks or splits

[Deltak]

For what it's worth,
it appears that you are getting air from the combustion chamber leaking ito the cooling water.
Either the head gasket has failed - most likely,or a crack or possibly a porous pin hole leak in the head.

Either way, It off with the head!

A simple test is to fill the radiator, block the overflow and, with the engine running (cold), place your palm across the radiator cap opening. If there is gasses escaping, you will feel the build-up of pressure very quickly.

Deltak

[Not_An_Abba_Fan]

When the engine is switched off the temperature of the coolant actually increases and it expands flowing into the overflow. It sounds like one of two things, either there is an air lock in the system or the radiator cap is buggered. Does the Tata have a bleed nipple on the front of the head or on the thermostat housing somewhere? Is the radiator fill spout higher or lower than the top of the head? (not the rocker cover). You will have to bleed the system thoroughly to remove all air is it has an air lock.

[HARVZ-6]

try a new cap maybe

[commsirac]

the over flow pipe isnt blowing water out as there is no brown water mud on the end of the new pipe

when you stop and turn the engine off you can hear it bubbling away really fast for a minute into the overflow

before a drive this morning the radiator was full to the top, over flow was on max,
now its down a inch and half and still on max for overflow


no temp guage as it doesnt work and the system was flushed and filled a month ago as we thought it was blocked

So really you have narrowed it down to that the coolant isnt getting pushed back in. Do the hoses look like they have collapsed at all when the system has cooled down, if they have this would indicate the system is airtight and just a problem with the renetry valve on the radiator cap. On the bottom of the cap is a small disk that you should be able to pull away with your fingers, it is this action that allows coolant to be forced back in, perhaps try another cap.

Or if the system hoses dont look like they have collapsed, the system is not airtight, this could include the coolant recovery hose. Get the system pressure tested when the motor is cold, or even go around with the screwdriver and tighten up all the hoses when it is cold.

[VL Berlina 5speed]

For what it's worth,
it appears that you are getting air from the combustion chamber leaking ito the cooling water.
Either the head gasket has failed - most likely,or a crack or possibly a porous pin hole leak in the head.

Either way, It off with the head!

A simple test is to fill the radiator, block the overflow and, with the engine running (cold), place your palm across the radiator cap opening. If there is gasses escaping, you will feel the build-up of pressure very quickly.

Deltak

this is what we have come down to think, either small leak and compresion is pumping
but no cream under cap, no mist what so ever out of the exhaust

ill try what you have recokmended in a sec

When the engine is switched off the temperature of the coolant actually increases and it expands flowing into the overflow. It sounds like one of two things, either there is an air lock in the system or the radiator cap is buggered. Does the Tata have a bleed nipple on the front of the head or on the thermostat housing somewhere? Is the radiator fill spout higher or lower than the top of the head? (not the rocker cover). You will have to bleed the system thoroughly to remove all air is it has an air lock.

ive looked over all the system but cant find a bleed nipple
radiator is deff higher then the head/ rocker cover or any manifold

so in it should allow most air locks into the radiator

try a new cap maybe

So really you have narrowed it down to that the coolant isnt getting pushed back in. Do the hoses look like they have collapsed at all when the system has cooled down, if they have this would indicate the system is airtight and just a problem with the renetry valve on the radiator cap. On the bottom of the cap is a small disk that you should be able to pull away with your fingers, it is this action that allows coolant to be forced back in, perhaps try another cap.

Or if the system hoses dont look like they have collapsed, the system is not airtight, this could include the coolant recovery hose. Get the system pressure tested when the motor is cold, or even go around with the screwdriver and tighten up all the hoses when it is cold.

we have purchesed a new radiator cap which is suited to a tata utes radiator and it still is alowing air out, the coolant is not entering the overflow bottle its just air


so as Deltak said its leaning towards the head
personally i think the head has a leak in the head, the compression is blowing into the coolant system and blowing throught the overflow

the coolant disappering is getting sucked into the cylinder and then pushed throught the turbo where its vaporised,
hence why we cant find the missing coolant

[VL Berlina 5speed]

did deltaks test and instant presure

put some chem i weld yesterday and its not bubbling asmuch, so think ill chuck another bottle in
nothing to loose now, next place is a wreakers