Any mechanics out there - help advice needed

Arthurgray50@blu · 18-03-2011, 14:27

I have a Vuaxhall Astra R reg, and we have a problem, that l think my mechanic won't tell us what the problem is.

When we take the water holder tank cap off, we get a build up of pressure and it 'hisses' when it comes off,

We have checked for oil in the water (ie Cycnlinder head gasket gone) and there is no change of fluid, we have checked the oil in case of oil in water again.

The temp doesn't go up, It was out of water the other day, but fresh water has remained.

Could it be the cap itself won't release the pressure ?

ANY IDEAS ?

Gary L · 18-03-2011, 14:48

There will be a build up of pressure if the engine's hot and you take the cap off. the temperature not going up. is that the temperature gauge? probably a faulty thermostat.

if you mean the heater's not blowing hot then you probably got an air lock.

**Lew** · 18-03-2011, 14:53

Moved to Lifestyle as it doesn't really belong in Current Affairs

videodj · 18-03-2011, 14:59

Could be a few things, leaking pipe or radiator, faulty thermostat or water pump. Unlikely that it will be the cap it's self. Needs looking at soon or could cause more serious problems.

All cars build up some pressure when there warm (found that out the hard way when I was an apprentice and burn my arm!) so it may be normal and your temperature sender unit is faulty.

Do you get any white smoke from the exhaust? This would sugest it's burning water.

First thing to try is to remove the thermostat and place it in boiling water to see if it opens. Run the car without it (take thermostat out and replace hosuing). If it's the thermostat the car will run at a very low temperature as the water will constantly flow. If the levels don't go down when the car is left over night, it has to be a mechanical fault such as the water pump or a pipe that only leaks at pressure (maybe a pin hole).

heero_yuy · 18-03-2011, 15:23

It's quite normal to have some residual air/vapour pressure in the cooling system even when it is cold. Infact it's a good sign that there is no residual leakage. Certainly my Metro has quite a lot of residual pressure. Always has since I first got it 14 odd years ago. Still going strong.

I suspect you're worrying unnecessarilly here especially if the water is staying clean and there's no mayo build up on the oil filler cap and the oil is clean.

Arthurgray50@blu · 19-03-2011, 11:44

i want members for all there help on this, we have seen a mechanic that l haven't seen in a few years, and he is fixing it tomorrow - water pump.

It appears that all the people that we have had looking at it, and this mate of mine, went straight to it, after what we told him what the problem was - cheers