ricklawn
|
| posted on 6/3/08 at 05:02 PM |
|
|
pressurised system
I have got a 1.8 zetec with a polo radiator, can anyone please tell me if it should be pressurised. i have had it up to temp but when i take cap off
nothing happens.
thanks
Rick
|
|
|
|
|
onzarob
|
| posted on 6/3/08 at 05:34 PM |
|
|
yes. cooling systems need to form pressure as to raise the boiling temperature of water. to much is also bad
|
|
|
ricklawn
|
| posted on 6/3/08 at 06:18 PM |
|
|
there seems to be no pressure at all in mine, and i have no leaks, water or air. so how do i pressurise?
|
|
|
bimbleuk
|
| posted on 6/3/08 at 06:34 PM |
|
|
The first thing that springs to mind is the pressure cap on your header tank.
Water/coolant based systems will run up to 15 psi of pressure so its quite obvious when you loosen the cap. Obviously be aware of the dangers of hot
pressurised coolant.
|
|
|
RazMan
|
| posted on 6/3/08 at 07:09 PM |
|
|
When you say that it is coming up to temp, what is the actual temp? 90 degrees or so? If so you will propably not generate any pressure unless you go
above 100 degrees.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
ricklawn
|
| posted on 6/3/08 at 07:12 PM |
|
|
to bleed the air system do i have to realy need to boil the system up then? i got up to temp at around 95 and switched off
|
|
|
onzarob
|
| posted on 6/3/08 at 07:49 PM |
|
|
quote:
Originally posted by ricklawn
to bleed the air system do i have to realy need to boil the system up then? i got up to temp at around 95 and switched off
How long did you run it when it reached 95, did it stop there or you just switched off.
I assume your fan runs up around 100ish so why not see if the car runs up to the fan coming on and then see if it comes back down as the fan takes
effect.
You may have an airlock, but don't remove the cap to check if there is pressure, try squeezing different coolant pipes to see if its hard/soft.
Allot safer than scolding yourself
|
|
|
SPYDER
|
| posted on 6/3/08 at 07:49 PM |
|
|
You almost certainly have a faulty pressure cap. The system will be starting to pressurise as soon as it starts to warm up. It should certainly have
pressure in it at 95 degrees.
Try a different cap. And beware of the dangers of hot pressurised coolant.
Geoff.
|
|
|
ricklawn
|
| posted on 6/3/08 at 08:15 PM |
|
|
i turned it off when it got upto 95ish as the fan hadn't come on so also need to check wires. the expantion bottle is plastic type with snug
fitting plastic cap.
|
|
|
onzarob
|
| posted on 6/3/08 at 08:22 PM |
|
|
Is it a new plastic cap?
|
|
|
ricklawn
|
| posted on 6/3/08 at 08:22 PM |
|
|
old
|
|
|
onzarob
|
| posted on 6/3/08 at 08:34 PM |
|
|
Get a new one before pulling the rest apart they do fail
|
|
|
ricklawn
|
| posted on 6/3/08 at 09:34 PM |
|
|
cheers onzarob, will do
|
|
|
SPYDER
|
| posted on 6/3/08 at 09:46 PM |
|
|
So is there a pressure cap on the radiator itself, or is the pressure cap on the header tank? The "snug fitting cap" you describe does
not sound like a pressure cap. Where did you get the header tank from. What vehicle is it from? It sounds like you may not actually have a pressure
cap on your system at all, unless it is on the radiator itself.
The fan probably won't cut in till the temp goes near or over 100, which could be accompanied by lots of steam if you are running
un-pressurised.
It is a good idea to have a manual switch for the fan as well as the temperature activated one.
Geoff.
|
|
|
onzarob
|
| posted on 6/3/08 at 10:10 PM |
|
|
The cap on my Audi and my previous Golf MK1 is a snug fitting cap and I've seen the header tanks used on plenty locosts.
I do feel that the newer caps add to the confusion as they do look like a seal unit, but they are still pressure release caps.
|
|
|
Macbeast
|
| posted on 6/3/08 at 10:23 PM |
|
|
But is the expansion bottle cap a pressure cap ?
Older systems had pressure cap on radiator and expansion bottle was just an overflow and un pressurised.
Newer systems have pressure cap on the expansion bottle. You might have older type expansion bottle which with Polo rad means you have no pressure cap
at all and hence no pressure.
|
|
|
contaminated
|
| posted on 11/3/08 at 09:34 PM |
|
|
Easy enough to find out. The plastic ones don't have an exterior outlet like radiator caps, but they do vent inside the cap. Mine has four
vertical grooves on the inside of the cap. When pressure builds above a certain point a spring compresses and alows the vapour to vent via the
grooves.
|
|
|
