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[star_whites]

How do I tell when it has presurised, because if I keep removing it to check then its obviously going to take longer to do??

[TheBoy]

How do I tell when it has presurised, because if I keep removing it to check then its obviously going to take longer to do??

Run it from cold for 60s, and if its pressurised then, probably not good.  Can also check if top hose getting too hard.

If answer is no, may be a faulty cap and/or expansion bottle.

[star_whites]

I have noticed that the expansion tank has lots of small cracks that have appeared around the neck below the cap. I also noticed that when it was stood after the 35 mile journey that I could here presure being released from the bottle when the engine was not running is this normal??

[TheBoy]

I have noticed that the expansion tank has lots of small cracks that have appeared around the neck below the cap. I also noticed that when it was stood after the 35 mile journey that I could here presure being released from the bottle when the engine was not running is this normal??

The hissing isn't.  Is the top hose getting hard after a run?

[tunnie]

could be a weak cap, i know someone who kept blowing coolant tank caps  
Take it on a run, then when you get back release the cap and have a good sniff around it, and in the tank, can you smell fuel?

Any water on the dip stick?

Do you get excessive steam from the exhaust?

And did that person have a failed head?

 

There could be other reasons, blocked /silted rad would not help...

Has it had any RadWeld in it?

[TheBoy]

could be a weak cap, i know someone who kept blowing coolant tank caps  
Take it on a run, then when you get back release the cap and have a good sniff around it, and in the tank, can you smell fuel?

Any water on the dip stick?

Do you get excessive steam from the exhaust?

And did that person have a failed head?

 

There could be other reasons, blocked /silted rad would not help...

Has it had any RadWeld in it?

Overheating aside, overpresurisation is caused by HG/Head allowing combustion gasses into coolant, or due to coolant leaks.

[star_whites]

The radiator was brand new in january, however on the leak side, I have forgot that where I park my car at work is on a very steep slope and I did notice the other day that there appeared to be a residue of water under the car when I came out, at first I didnt think anything of it but it was there again the next day. I reverse into my spot which leaves the front passenger side of the car facing downhill at a steep angle. Is is possible its dragging air and causing a blockage??

[star_whites]

Just been outside to see if cars cooled down, but its still hot. On removing the pressure cap it hissed slightly, however on smelling the tank there is no smell of fuel just antifreeze mixture.

Thinking about it though, the top hose from rad to thermostat housing did appear quite hard when I checked it when I parked up as I did give it a squeeze but not too hard as it was bloody red hot  

[star_whites]

OK, I will start the car in the morning when cold and time it for a minute, after that I will check the pressure cap and see what happens. I will then drive it too work and once there the car should be fully up to temp, so I will check the top hose for hardnous and report back!!  

[feeutfo]

I've not timed it. All I did was leave it running without the cap on to see if fan came on. I know when the head went on it in january the interior fan went cold and steam started coming from exhaust but the fan is blowing hot and no steam. It also does not appear to be using any water other than the bit thats leaking from expansion tank.

Could the cracks in the bottle be from previous head failure in january?

[star_whites]

Ok a quick update.

I got up this morning and thought I would try the car straight away (this was over 2 hrs ago by the way and it was raining lol)

I checked the fluid level which is correct, then made sure the cap was tight. Started the car and ran for 1 minute. Stopped and released cap, there was no pressure. Tightned cap and then set off to work. After 2 1/2 minutes I pulled over and removed the cap, there was a very weak hiss. Prior to removing cap I checked top hose and this was soft.

I then refitted cap and drove the ten minute drive to work with varying speeds from 30 - 70. Stopped and checked hose, this was still soft but bloody hot. No coolant had been forced out. I started to remove cap and you could hear the pressure being released as the fluids shop up to cap (this point I retightned).

So does this rule out the headgasket failure or is it a possibilty that it is only doing it on long journeys and is only just starting to go??

The expansion tank was relaced in january as I accidentaly melted the original tank with my 110v floodlight  

[feeutfo]

im no expert but would tend to say, not hg. But what else can cause bottle failure in 8 months? A blockage or buggerd cap?

[TheBoy]

I don't suspect HG.

Was cap replaced? If not, might be worth getting one (about a fiver)

[star_whites]

To be tottally honest, the bottle & cap were not brand new, as my brother works at a local breakers and it was the quickest way of getting hold of one. It was off a 2000 model, but it was like new.

Im wondering if there is a leak somewere and its allowing air into the system and causing an airlock from time to time??

[star_whites]

Do you think its best to try a new bottle and cap then or do you think it could be down to a leak letting in air??