Air Lock - any advice welcome - sorted thanks

Levislude · Post by **Levislude** » Mon Oct 22, 2012 3:04 pm

Bit of a hijack here - sorry. Does anybody know if the 2.0 F20a4 has a bleed valve? I only ask because I'm fitting a new rad later this week.

Thanks

Post by **Merlin** » Mon Oct 22, 2012 3:15 pm

^^ The 4th gen service manual shows it to be in the same place.

Post by **indigolemon** » Mon Oct 22, 2012 3:37 pm

That's an odd one Nick. Replacing the rad I did the following:

Drained the coolant
Removed the old rad, fitted the new one
Opened the bleed nipple, then filled via the rad
Kept filling till a constant stream of coolant was flowing from the bleed nipple, then nipped it up
Topped off the rad, fitted the cap
Filled the expansion tank to max
Ran the car

The filler neck on the radiator is higher than the bleed nipple - so if you have fluid there, you should have fluid/air coming out of the bleed nipple.

BMCC · Post by **BMCC** » Mon Oct 22, 2012 3:40 pm

From memory I opened the bleed bolt then filled the radiator with coolant (put the heater to max first). The bleed bolt was closed when coolant started running out without any bubbles in it. Basically you were using the coolant to push the air out (car was on stands). The system was then topped up and ran with the cap off for about 1/2 hr. I put plenty of rags round the top of the rad as it can expand and over flow slightly. I let the car stand over night then topped it up in the morning. No problems with air locks etc.

Post by **Merlin** » Mon Oct 22, 2012 3:57 pm

His rad cap is open and the bottom hose is cold, is there a reason why this is other than his thermostat being fooked? An air block stopping the water getting to the thermostat?

Post by **vanzep** » Mon Oct 22, 2012 4:00 pm

well spent the last hour trying to fix it and im not convinced i have

bled air out thru bleed valve - top and bottom rad hoses were hot - air bubbles thru bleed valve initially and then nothing....seems there is very little pressure in system..still no fan kick in...wtf
maybe its becasue its freezing cold outside - i just dont know.
i hate to admit but i think car has been running hot for a while now-fan used to kick in when at idle. new water pump was fitted when i did the belts....

Post by **Merlin** » Mon Oct 22, 2012 4:03 pm

With the engine hot, rad cap on, bleed valve closed, are there and visable leaks? You might need to move the car to see (water already on the ground so hard to spot new water).

Post by **vanzep** » Mon Oct 22, 2012 4:17 pm

no visible leaks-ive moved the car and taken in for short run
im going back out to try again

going to try the indigolem and then the BMCC method
back in hour or so...

Post by **Merlin** » Mon Oct 22, 2012 4:35 pm

At least you got the bottom hose hot now.

judderod · Post by **judderod** » Mon Oct 22, 2012 4:43 pm

Check theres fluid right underneath the rad cap, then close it off. Start the engine, open the bleed valve (only needs 1/2 a turn back) and rev it up. Then watch a nice fountain appear under your bonnet. Settle back to idle, check for no bubbles and close off the valve (don't burn yourself on the fooking hot water shooting out).

With the bonnet open, on a cold day, like you say it probably won't get hot enough to trip the fans at idle. One other thing to check, IIRC there's a switch that trips the fans, it doesn't use the thermostat the ECU sees? Could be wrong.