thereisnospoon

Just changed the coolant and header tank cap, the car is running fine and temp gauge normal, just the rad hoses are hard with pressure and wasnt before the change, can anyone help. thanks guys

incarsolutions

iTrader: (12)

airlock.

thereisnospoon

How do i sort that out?

Rich D

iTrader: (12)

bleed the system

thereisnospoon

is this easy to do?

Splitpin

Right, count to ten everyone.

Nospoon, hard rad pipes is not, in itself, a definative iindication of an airlock. It can also be an indication that there isn't an airlock and that everything's good.

The system's supposed to be pressurised when hot, that's why header tank caps are marked with a release pressure. If you weren't getting hard pipes before when the engine was hot, chances are your system was under-filled before you did your coolant change. Before going any further answer these questions and it'll be easier for us help you work out what, if anything, is up:

1. What MY is your car?
2. Your new header tank cap - what crack pressure's written on it, and is it the same as the one you took off?
3. When you had the engine running, did/do you get hot air out of the air vents with the fan on and the dial turned all the way to hot?
4. Can you feel coolant in the upper and lower rad hoses - i.e. are they both hot?
5. Wait til the engine's cooled and open the expansion tank. Is it still full, empty, or somewhere between the two?

Answer us those and then we'll see where we are.

dj219957

splitpin, couldnt have put it better myself.

another misconception, hot top hose, colder bottom hose = bad. WRONG!
that means rad is working

thereisnospoon

Ah never mind then, heater works fine, both hose's are hot and water level is fine. The cap I took off was one with a pressure button, and the one I put on hasn't. Thanks guys

Butty

iTrader: (2)

Under what circumstances is that wrong

dj219957

if the bottom hose was as hot as the top then the rad wouldnt be doing its job would it!

Butty

iTrader: (2)

So when the car is parked up and idling, the hoses are different temps?

dj219957

the water is pumped from top to bottom as i understand, so there should always be a temp difference, large or small depending on if parked or moving.

If the termostat is closed the top hose will be hotter as well.

Butty

iTrader: (2)

If you can feel a temp difference by hand of the top and bottom hoses then either its just warming up and the thermostat hasn't opened - or if warmed up and driven for 30 mins or more then there is an air lock in the rad which IS BAD.
In the later case, the coolant sensor will kick the fans in, but they will keep blowing as the air lock prevents coolant flow through the rad, so the coolant running past the sensor doesn't get cooler. The rad may be either cold or slightly warm to touch.

It is not a misconception, but a good sign of a problem that needs sorting.

thereisnospoon

I've also noticed the fan kicking in when i stop which it never did before? also the water in he overflow bottle isnt pink like my coolant?