Could be more serious than 1st thought

[hoj]

Some of you may have seen my post “heater” where the heater was blowing cold anyway decided it was the matrix so bought a new one less than an hour later the new one was in and all seemed good heater was blowing hot and working ok

However

The top hose keeps going hard and the cooling system pressurising when opening the header tank cap coolant bubbles/hisses out the level obviously goes down by about 1/2 pint and the top hose goes soft again

There is NO coolant leaking anywhere from pipes or radiator
There is NO water in the oil (No frothing)
There is no smoke or steam coming from the exhaust
The thermostat seems to be working as it should all pipes are hot
The new matrix seems to be working fine inlet and outlet pipes are hot
The engine seems to be running fine
The temp gauge on the dash stays at 12 O’clock

So is it head gasket or not?
Think all air in system has dissapeared as well

[4x4]

You should not be opening the cooling system when it is hot.

First thing I would do is take the car for a good half hour drive then when you return home leave the car to cool down overnight. Next morning check and top up to the required level. Once you have done that fit a new genuine Volvo expansion cap.

[hoj]

4x4 Thanks I’ve actually drove the car Friday and yesterday 20/30 miles each day and it will come up with the message coolant level low so fill it up again (cup full to 1/2 pint) then all ok till the next trip when it does it again
Water is going somewhere but nothing obvious
Just been 30 mile round trip now and message came up again after 10 mile or so but temp gauge stays the same

[Simmy]

try looking around the egr cooler its not unknown for there to be small leaks or even pin holes in the cooler check egr cooler hoses .

[richmac]

Hi Hoj,

Could you give some more info so we can try and help you better?

Which engine do you have?
Was this happening before you changed the matrix?
Is your coolant clear or contaminated?
Is there any debris in the expansion tank?


Best regards,

Rich.

[hoj]

Could try that Simmy but doesn’t seem to be any steam or white smoke coming from exhaust
Getting fed up with this car now

[hoj]

Rich Mac

It’s the 2.4 D5 euro 4 185hp engine
Only changed matrix as heater started blowing cold the old matrix was full of a cream coloured gunk also brown sludge (radweld??) possibly
Coolant is clear ……. well red with anti freeze
NO debris in header tank
System just keeps pressurising and losing cup full of coolant each time

[Simmy]

egr cooler leaks would show under the bonnet not in the exhaust as you have now said that the matrix was gunged up its possible that the bypass hole in the top of the thermostat is also blocked with the same gunge its a very small hole so this is a definite possibility when replacing the stat make sure to have the bypass hole at the top.

[4x4]

Originally Posted by hoj

Rich Mac

...the old matrix was full of a cream coloured gunk also brown sludge

Water mixing with oil would/will produce brown sludge. Have you checked the oil? Also check as per Simmy's post and any oil coolers fitted to the car

[hoj]

Checked the oil all is fine
Looked at exhaust NO smoke or steam
Looked all over engine NO leaks
Looked under front of car with under tray OFF NO leaks
But as I say water is going somewhere but nothing obvious